[PATCH 1/3] Inherit OID system column automatically for partitions

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[PATCH 1/3] Inherit OID system column automatically for partitions
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* [PATCH 1/3] Inherit OID system column automatically for partitions
@ 2017-02-13 04:32  amit <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: amit @ 2017-02-13 04:32 UTC (permalink / raw)

Currently, WITH OIDS must be explicitly specified when creating a
partition if the parent table has the OID system column.  Instead,
inherit it automatically, possibly overriding any explicit WITHOUT
OIDS specification.  Per review comment from Simon Riggs
---
 doc/src/sgml/ddl.sgml                      |  8 --------
 doc/src/sgml/ref/create_table.sgml         | 12 +++++-------
 src/backend/commands/tablecmds.c           | 21 ++++++++-------------
 src/test/regress/expected/create_table.out | 18 +++++++++++++-----
 src/test/regress/sql/create_table.sql      | 10 ++++++----
 5 files changed, 32 insertions(+), 37 deletions(-)

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index f909242e4c..5779eac43d 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -2863,14 +2863,6 @@ VALUES ('Albany', NULL, NULL, 'NY');
 
      <listitem>
       <para>
-       If the partitioned table specified <literal>WITH OIDS</literal> then
-       each partition must also specify <literal>WITH OIDS</literal>. Oids
-       are not automatically inherited by partitions.
-      </para>
-     </listitem>
-
-     <listitem>
-      <para>
        One cannot drop a <literal>NOT NULL</literal> constraint on a
        partition's column, if the constraint is present in the parent table.
       </para>
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index e0f7cd9b93..87a3443ee2 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -301,13 +301,11 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
 
      <para>
       A partition cannot have columns other than those inherited from the
-      parent.  If the parent is specified <literal>WITH OIDS</literal> then
-      the partitions must also explicitly specify <literal>WITH OIDS</literal>.
-      Defaults and constraints can optionally be specified for each of the
-      inherited columns.  One can also specify table constraints in addition
-      to those inherited from the parent.  If a check constraint with the name
-      matching one of the parent's constraint is specified, it is merged with
-      the latter, provided the specified condition is same.
+      parent.  Defaults and constraints can optionally be specified for each
+      of the inherited columns.  One can also specify table constraints in
+      addition to those inherited from the parent.  If a check constraint with
+      the name matching one of the parent's constraint is specified, it is
+      merged with the latter, provided the specified condition is same.
      </para>
 
      <para>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index f33aa70da6..3cea220421 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -634,19 +634,14 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 									  relkind == RELKIND_PARTITIONED_TABLE));
 	descriptor->tdhasoid = (localHasOids || parentOidCount > 0);
 
-	if (stmt->partbound)
-	{
-		/* If the parent has OIDs, partitions must have them too. */
-		if (parentOidCount > 0 && !localHasOids)
-			ereport(ERROR,
-					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("cannot create table without OIDs as partition of table with OIDs")));
-		/* If the parent doesn't, partitions must not have them. */
-		if (parentOidCount == 0 && localHasOids)
-			ereport(ERROR,
-					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("cannot create table with OIDs as partition of table without OIDs")));
-	}
+	/*
+	 * If a partitioned table doesn't have the system OID column, then none
+	 * of its partitions should have it.
+	 */
+	if (stmt->partbound && parentOidCount == 0 && localHasOids)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("cannot create table with OIDs as partition of table without OIDs")));
 
 	/*
 	 * Find columns with default values and prepare for insertion of the
diff --git a/src/test/regress/expected/create_table.out b/src/test/regress/expected/create_table.out
index fc92cd92dd..20eb3d35f9 100644
--- a/src/test/regress/expected/create_table.out
+++ b/src/test/regress/expected/create_table.out
@@ -524,16 +524,24 @@ DROP TABLE temp_parted;
 CREATE TABLE no_oids_parted (
 	a int
 ) PARTITION BY RANGE (a) WITHOUT OIDS;
-CREATE TABLE fail_part PARTITION OF no_oids_parted FOR VALUES FROM (1) TO (10 )WITH OIDS;
+CREATE TABLE fail_part PARTITION OF no_oids_parted FOR VALUES FROM (1) TO (10) WITH OIDS;
 ERROR:  cannot create table with OIDs as partition of table without OIDs
 DROP TABLE no_oids_parted;
--- likewise, the reverse if also true
+-- If the partitioned table has oids, then the partition must have them.
+-- If the WITHOUT OIDS option is specified for partition, it is overridden.
 CREATE TABLE oids_parted (
 	a int
 ) PARTITION BY RANGE (a) WITH OIDS;
-CREATE TABLE fail_part PARTITION OF oids_parted FOR VALUES FROM (1) TO (10 ) WITHOUT OIDS;
-ERROR:  cannot create table without OIDs as partition of table with OIDs
-DROP TABLE oids_parted;
+CREATE TABLE part_forced_oids PARTITION OF oids_parted FOR VALUES FROM (1) TO (10) WITHOUT OIDS;
+\d+ part_forced_oids
+                             Table "public.part_forced_oids"
+ Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description 
+--------+---------+-----------+----------+---------+---------+--------------+-------------
+ a      | integer |           | not null |         | plain   |              | 
+Partition of: oids_parted FOR VALUES FROM (1) TO (10)
+Has OIDs: yes
+
+DROP TABLE oids_parted, part_forced_oids;
 -- check for partition bound overlap and other invalid specifications
 CREATE TABLE list_parted2 (
 	a varchar
diff --git a/src/test/regress/sql/create_table.sql b/src/test/regress/sql/create_table.sql
index 5f25c436ee..f41dd71475 100644
--- a/src/test/regress/sql/create_table.sql
+++ b/src/test/regress/sql/create_table.sql
@@ -493,15 +493,17 @@ DROP TABLE temp_parted;
 CREATE TABLE no_oids_parted (
 	a int
 ) PARTITION BY RANGE (a) WITHOUT OIDS;
-CREATE TABLE fail_part PARTITION OF no_oids_parted FOR VALUES FROM (1) TO (10 )WITH OIDS;
+CREATE TABLE fail_part PARTITION OF no_oids_parted FOR VALUES FROM (1) TO (10) WITH OIDS;
 DROP TABLE no_oids_parted;
 
--- likewise, the reverse if also true
+-- If the partitioned table has oids, then the partition must have them.
+-- If the WITHOUT OIDS option is specified for partition, it is overridden.
 CREATE TABLE oids_parted (
 	a int
 ) PARTITION BY RANGE (a) WITH OIDS;
-CREATE TABLE fail_part PARTITION OF oids_parted FOR VALUES FROM (1) TO (10 ) WITHOUT OIDS;
-DROP TABLE oids_parted;
+CREATE TABLE part_forced_oids PARTITION OF oids_parted FOR VALUES FROM (1) TO (10) WITHOUT OIDS;
+\d+ part_forced_oids
+DROP TABLE oids_parted, part_forced_oids;
 
 -- check for partition bound overlap and other invalid specifications
 
-- 
2.11.0


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^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v24 2/5] Add conditional lock feature to dshash
@ 2018-09-27 02:15  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2018-09-27 02:15 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. This commit adds new
interfaces for dshash_find and dshash_find_or_insert. The new
interfaces have an extra parameter "nowait" taht commands not to wait
for lock.
---
 src/backend/lib/dshash.c | 69 ++++++++++++++++++++++++++++++++++++----
 src/include/lib/dshash.h |  6 ++++
 2 files changed, 68 insertions(+), 7 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 4f0c7ec840..60a6e3c0bc 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -394,19 +394,48 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  */
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
+{
+	return dshash_find_extended(hash_table, key, exclusive, false, NULL);
+}
+
+/*
+ * Addition to dshash_find, returns immediately when nowait is true and lock
+ * was not acquired. Lock status is set to *lock_failed if any.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool *lock_acquired)
 {
 	dshash_hash hash;
 	size_t		partition;
 	dshash_table_item *item;
 
+	/* allowing !nowait returning the result is just not sensible */
+	Assert(nowait || !lock_acquired);
+
 	hash = hash_key(hash_table, key);
 	partition = PARTITION_FOR_HASH(hash);
 
 	Assert(hash_table->control->magic == DSHASH_MAGIC);
 	Assert(!hash_table->find_locked);
 
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
+	if (nowait)
+	{
+		if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partition),
+									  exclusive ? LW_EXCLUSIVE : LW_SHARED))
+		{
+			if (lock_acquired)
+				*lock_acquired = false;
+			return NULL;
+		}
+	}
+	else
+		LWLockAcquire(PARTITION_LOCK(hash_table, partition),
+					  exclusive ? LW_EXCLUSIVE : LW_SHARED);
+
+	if (lock_acquired)
+		*lock_acquired = true;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
@@ -441,6 +470,22 @@ void *
 dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
+{
+	return dshash_find_or_insert_extended(hash_table, key, found, false);
+}
+
+/*
+ * Addition to dshash_find_or_insert, returns NULL if nowait is true and lock
+ * was not acquired.
+ *
+ * Notes above dshash_find_extended() regarding locking and error handling
+ * equally apply here.
+ */
+void *
+dshash_find_or_insert_extended(dshash_table *hash_table,
+							   const void *key,
+							   bool *found,
+							   bool nowait)
 {
 	dshash_hash hash;
 	size_t		partition_index;
@@ -455,8 +500,16 @@ dshash_find_or_insert(dshash_table *hash_table,
 	Assert(!hash_table->find_locked);
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (nowait)
+	{
+		if (!LWLockConditionalAcquire(
+				PARTITION_LOCK(hash_table, partition_index),
+				LW_EXCLUSIVE))
+			return NULL;
+	}
+	else
+		LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
+					  LW_EXCLUSIVE);
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
@@ -626,9 +679,11 @@ dshash_memhash(const void *v, size_t size, void *arg)
  * As opposed to the equivalent for dynanash, the caller is not supposed to
  * delete the returned element before continuing the scan.
  *
- * If consistent is set for dshash_seq_init, the whole hash table is
- * non-exclusively locked. Otherwise a part of the hash table is locked in the
- * same mode (partition lock).
+ * If consistent is set for dshash_seq_init, the all hash table
+ * partitions are locked in the requested mode (as determined by the
+ * exclusive flag), and the locks are held until the end of the scan.
+ * Otherwise the partition locks are acquired and released as needed
+ * during the scan (up to two partitions may be locked at the same time).
  */
 void
 dshash_seq_init(dshash_seq_status *status, dshash_table *hash_table,
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 79698a6ad6..67f7d77f71 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -90,8 +90,14 @@ extern void dshash_destroy(dshash_table *hash_table);
 /* Finding, creating, deleting entries. */
 extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait,
+								  bool *lock_acquired);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_or_insert_extended(dshash_table *hash_table,
+											const void *key, bool *found,
+											bool nowait);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.23.0


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^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH 2/5] Add conditional lock feature to dshash
@ 2018-09-27 02:15  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2018-09-27 02:15 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. This commit adds new
interfaces for dshash_find and dshash_find_or_insert. The new
interfaces have an extra parameter "nowait" taht commands not to wait
for lock.
---
 src/backend/lib/dshash.c | 64 +++++++++++++++++++++++++++++++++++++---
 src/include/lib/dshash.h |  6 ++++
 2 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 7675370058..7766fa7704 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -394,19 +394,51 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  */
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
+{
+	return dshash_find_extended(hash_table, key, exclusive, false, NULL);
+}
+
+/*
+ * The version of dshash_find, which is allowed to return immediately on lock
+ * failure. Lock status is set to *lock_failed in that case.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool *lock_acquired)
 {
 	dshash_hash hash;
 	size_t		partition;
 	dshash_table_item *item;
 
+	/*
+	 * No need to return lock resut when !nowait. Otherwise the caller may
+	 * omit the lock result when NULL is returned.
+	 */
+	Assert(nowait || !lock_acquired);
+
 	hash = hash_key(hash_table, key);
 	partition = PARTITION_FOR_HASH(hash);
 
 	Assert(hash_table->control->magic == DSHASH_MAGIC);
 	Assert(!hash_table->find_locked);
 
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
+	if (nowait)
+	{
+		if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partition),
+									  exclusive ? LW_EXCLUSIVE : LW_SHARED))
+		{
+			if (lock_acquired)
+				*lock_acquired = false;
+			return NULL;
+		}
+	}
+	else
+		LWLockAcquire(PARTITION_LOCK(hash_table, partition),
+					  exclusive ? LW_EXCLUSIVE : LW_SHARED);
+
+	if (lock_acquired)
+		*lock_acquired = true;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
@@ -441,6 +473,22 @@ void *
 dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
+{
+	return dshash_find_or_insert_extended(hash_table, key, found, false);
+}
+
+/*
+ * The version of dshash_find_or_insert, which is allowed to return immediately
+ * on lock failure.
+ *
+ * Notes above dshash_find_extended() regarding locking and error handling
+ * equally apply here.
+ */
+void *
+dshash_find_or_insert_extended(dshash_table *hash_table,
+							   const void *key,
+							   bool *found,
+							   bool nowait)
 {
 	dshash_hash hash;
 	size_t		partition_index;
@@ -455,8 +503,16 @@ dshash_find_or_insert(dshash_table *hash_table,
 	Assert(!hash_table->find_locked);
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (nowait)
+	{
+		if (!LWLockConditionalAcquire(
+				PARTITION_LOCK(hash_table, partition_index),
+				LW_EXCLUSIVE))
+			return NULL;
+	}
+	else
+		LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
+					  LW_EXCLUSIVE);
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index ad88f32cdd..a7d19c6a85 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -89,8 +89,14 @@ extern void dshash_destroy(dshash_table *hash_table);
 /* Finding, creating, deleting entries. */
 extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait,
+								  bool *lock_acquired);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_or_insert_extended(dshash_table *hash_table,
+											const void *key, bool *found,
+											bool nowait);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.23.0


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* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v29 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 99 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 56 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index fb7e23c4cb..b4dc8e1ece 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,61 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "insert" indicates insert mode. In this mode new entry is inserted and set
+ * *found to false. *found is set to true if found. "found" must be non-null in
+ * this mode.
+ *
+ * If nowait is true, the function immediately returns if required lock was not
+ * acquired.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +484,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +499,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 81a929b8d9..80a896a99b 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Wed_Apr__1_15_15_11_2020_923)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v29-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v30 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..ee612b778f 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" means the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Wed_Apr__1_17_37_23_2020_570)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v30-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v31 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Fri_Apr__3_17_31_17_2020_104)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v31-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v32 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Tue_Apr__7_16_38_17_2020_299)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v32-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v33 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Thu_Apr_30_13_22_05_2020_409)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v33-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v25 3/8] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 117 ++++++++++++++++++++++++---------------
 src/include/lib/dshash.h |   3 +
 2 files changed, 75 insertions(+), 45 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 2086bdbea9..9a9b818d86 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -386,6 +386,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -395,36 +399,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -442,30 +417,61 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
-	dshash_table_item *item;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
 
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+/*
+ * Find the key in the hash table.
+ *
+ * "insert" indicates insert mode. In this mode new entry is inserted and set
+ * *found to false. *found is set to true if found. "found" must be non-null in
+ * this mode.  exclusive may be false in insert mode, but this function may
+ * take exclusive lock temporarily when actual insertion happens.
+ *
+ * If nowait is true, the function immediately returns if required lock was not
+ * acquired.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
+	dshash_table_item *item;
+	bool		inserted = false;
+
+	/* must be exclusive when insert allowed */
+	Assert(!insert || found != NULL);
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = !inserted;
+	}
 	else
 	{
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
+
 		*found = false;
 
 		/* Check if we are getting too full. */
@@ -482,26 +488,47 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
 		}
 
+		/* need to upgrade the lock to exclusive mode */
+		if (!exclusive)
+		{
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			LWLockAcquire(PARTITION_LOCK(hash_table, partidx), LW_EXCLUSIVE);
+		}
+
 		/* Finally we can try to insert the new item. */
 		item = insert_into_bucket(hash_table, key,
 								  &BUCKET_FOR_HASH(hash_table, hash));
 		item->hash = hash;
 		/* Adjust per-lock-partition counter for load factor knowledge. */
 		++partition->count;
+
+		if (!exclusive)
+		{
+			/*
+			 * The entry can be removed while downgrading lock. Re-find it for
+			 * safety.
+			 */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			inserted = true;
+
+			goto restart;
+		}
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 81a929b8d9..80a896a99b 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Thu_Mar_19_20_30_04_2020_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v25-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v43 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index b829167872..9c90096f3d 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index c337099061..493e974832 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Dec_11_16_50_03_2020_915)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v43-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v44 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index b829167872..9c90096f3d 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index c337099061..493e974832 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Mon_Dec_21_17_16_20_2020_608)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v44-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v36 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.4


----Next_Part(Tue_Sep__8_17_55_57_2020_197)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v36-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v37 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.4


----Next_Part(Fri_Sep_25_09_27_26_2020_419)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v37-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v38 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index b829167872..9c90096f3d 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index c337099061..493e974832 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.4


----Next_Part(Thu_Oct__1_09_07_22_2020_252)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v38-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v39 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index b829167872..9c90096f3d 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index c337099061..493e974832 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.4


----Next_Part(Tue_Oct__6_10_06_44_2020_382)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v39-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v40 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index b829167872..9c90096f3d 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index c337099061..493e974832 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.4


----Next_Part(Wed_Nov__4_17_39_10_2020_208)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v40-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v41 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index b829167872..9c90096f3d 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index c337099061..493e974832 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.4


----Next_Part(Fri_Nov__6_09_27_56_2020_738)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v41-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v42 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index b829167872..9c90096f3d 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index c337099061..493e974832 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.4


----Next_Part(Wed_Nov_11_10_07_22_2020_796)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v42-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v34 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Mon_Jun__1_18_00_01_2020_089)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v34-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v35 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Mon_Jun__8_17_32_04_2020_489)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v35-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
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Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
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Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v33 3/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 1ef093e2e9..d7ee6de11e 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index 0ca9514021..5f7a60febd 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.18.2


----Next_Part(Fri_May_15_17_30_36_2020_111)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v33-0004-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v45 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Jan__8_10_24_34_2021_185)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v45-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v46 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_14_15_14_25_2021_903)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v46-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v47 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Jan_21_12_03_48_2021_284)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v47-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v57 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Mar_18_16_56_02_2021_947)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v57-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v48 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Fri_Mar__5_17_18_56_2021_497)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v48-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v49 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_16_53_11_2021_575)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v49-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v50 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar__9_18_29_34_2021_806)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v50-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v51 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_12_10_39_2021_432)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v51-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v52 2/7] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 520bfa0979..853d78b528 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Wed_Mar_10_17_51_37_2021_192)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v52-0003-Make-archiver-process-an-auxiliary-process.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v56 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Tue_Mar_16_10_27_55_2021_500)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v56-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* [PATCH v57 2/6] Add conditional lock feature to dshash
@ 2020-03-13 07:58  Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Kyotaro Horiguchi @ 2020-03-13 07:58 UTC (permalink / raw)

Dshash currently waits for lock unconditionally. It is inconvenient
when we want to avoid being blocked by other processes. This commit
adds alternative functions of dshash_find and dshash_find_or_insert
that allows immediate return on lock failure.
---
 src/backend/lib/dshash.c | 98 +++++++++++++++++++++-------------------
 src/include/lib/dshash.h |  3 ++
 2 files changed, 55 insertions(+), 46 deletions(-)

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 29ad767618..f79b6de245 100644
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -383,6 +383,10 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
  * the caller must take care to ensure that the entry is not left corrupted.
  * The lock mode is either shared or exclusive depending on 'exclusive'.
  *
+ * If found is not NULL, *found is set to true if the key is found in the hash
+ * table. If the key is not found, *found is set to false and a pointer to a
+ * newly created entry is returned.
+ *
  * The caller must not lock a lock already.
  *
  * Note that the lock held is in fact an LWLock, so interrupts will be held on
@@ -392,36 +396,7 @@ dshash_get_hash_table_handle(dshash_table *hash_table)
 void *
 dshash_find(dshash_table *hash_table, const void *key, bool exclusive)
 {
-	dshash_hash hash;
-	size_t		partition;
-	dshash_table_item *item;
-
-	hash = hash_key(hash_table, key);
-	partition = PARTITION_FOR_HASH(hash);
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
-
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition),
-				  exclusive ? LW_EXCLUSIVE : LW_SHARED);
-	ensure_valid_bucket_pointers(hash_table);
-
-	/* Search the active bucket. */
-	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
-
-	if (!item)
-	{
-		/* Not found. */
-		LWLockRelease(PARTITION_LOCK(hash_table, partition));
-		return NULL;
-	}
-	else
-	{
-		/* The caller will free the lock by calling dshash_release_lock. */
-		hash_table->find_locked = true;
-		hash_table->find_exclusively_locked = exclusive;
-		return ENTRY_FROM_ITEM(item);
-	}
+	return dshash_find_extended(hash_table, key, exclusive, false, false, NULL);
 }
 
 /*
@@ -439,31 +414,60 @@ dshash_find_or_insert(dshash_table *hash_table,
 					  const void *key,
 					  bool *found)
 {
-	dshash_hash hash;
-	size_t		partition_index;
-	dshash_partition *partition;
+	return dshash_find_extended(hash_table, key, true, false, true, found);
+}
+
+
+/*
+ * Find the key in the hash table.
+ *
+ * "exclusive" is the lock mode in which the partition for the returned item
+ * is locked.  If "nowait" is true, the function immediately returns if
+ * required lock was not acquired.  "insert" indicates insert mode. In this
+ * mode new entry is inserted and set *found to false. *found is set to true if
+ * found. "found" must be non-null in this mode.
+ */
+void *
+dshash_find_extended(dshash_table *hash_table, const void *key,
+					 bool exclusive, bool nowait, bool insert, bool *found)
+{
+	dshash_hash hash = hash_key(hash_table, key);
+	size_t		partidx = PARTITION_FOR_HASH(hash);
+	dshash_partition *partition = &hash_table->control->partitions[partidx];
+	LWLockMode  lockmode = exclusive ? LW_EXCLUSIVE : LW_SHARED;
 	dshash_table_item *item;
 
-	hash = hash_key(hash_table, key);
-	partition_index = PARTITION_FOR_HASH(hash);
-	partition = &hash_table->control->partitions[partition_index];
-
-	Assert(hash_table->control->magic == DSHASH_MAGIC);
-	Assert(!hash_table->find_locked);
+	/* must be exclusive when insert allowed */
+	Assert(!insert || (exclusive && found != NULL));
 
 restart:
-	LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
-				  LW_EXCLUSIVE);
+	if (!nowait)
+		LWLockAcquire(PARTITION_LOCK(hash_table, partidx), lockmode);
+	else if (!LWLockConditionalAcquire(PARTITION_LOCK(hash_table, partidx),
+									   lockmode))
+		return NULL;
+
 	ensure_valid_bucket_pointers(hash_table);
 
 	/* Search the active bucket. */
 	item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));
 
 	if (item)
-		*found = true;
+	{
+		if (found)
+			*found = true;
+	}
 	else
 	{
-		*found = false;
+		if (found)
+			*found = false;
+
+		if (!insert)
+		{
+			/* The caller didn't told to add a new entry. */
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+			return NULL;
+		}
 
 		/* Check if we are getting too full. */
 		if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
@@ -479,7 +483,8 @@ restart:
 			 * Give up our existing lock first, because resizing needs to
 			 * reacquire all the locks in the right order to avoid deadlocks.
 			 */
-			LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
+			LWLockRelease(PARTITION_LOCK(hash_table, partidx));
+
 			resize(hash_table, hash_table->size_log2 + 1);
 
 			goto restart;
@@ -493,12 +498,13 @@ restart:
 		++partition->count;
 	}
 
-	/* The caller must release the lock with dshash_release_lock. */
+	/* The caller will free the lock by calling dshash_release_lock. */
 	hash_table->find_locked = true;
-	hash_table->find_exclusively_locked = true;
+	hash_table->find_exclusively_locked = exclusive;
 	return ENTRY_FROM_ITEM(item);
 }
 
+
 /*
  * Remove an entry by key.  Returns true if the key was found and the
  * corresponding entry was removed.
diff --git a/src/include/lib/dshash.h b/src/include/lib/dshash.h
index a6ea377173..5b8114d041 100644
--- a/src/include/lib/dshash.h
+++ b/src/include/lib/dshash.h
@@ -91,6 +91,9 @@ extern void *dshash_find(dshash_table *hash_table,
 						 const void *key, bool exclusive);
 extern void *dshash_find_or_insert(dshash_table *hash_table,
 								   const void *key, bool *found);
+extern void *dshash_find_extended(dshash_table *hash_table, const void *key,
+								  bool exclusive, bool nowait, bool insert,
+								  bool *found);
 extern bool dshash_delete_key(dshash_table *hash_table, const void *key);
 extern void dshash_delete_entry(dshash_table *hash_table, void *entry);
 extern void dshash_release_lock(dshash_table *hash_table, void *entry);
-- 
2.27.0


----Next_Part(Thu_Mar_18_16_56_02_2021_947)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v57-0003-Shared-memory-based-stats-collector.patch"



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* small pg_dump code cleanup
@ 2024-06-05 15:13  Nathan Bossart <[email protected]>
  0 siblings, 1 reply; 236+ messages in thread

From: Nathan Bossart @ 2024-06-05 15:13 UTC (permalink / raw)
  To: pgsql-hackers

While reviewing Daniel's pg_dump patch [0], I was initially confused
because the return value of getTypes() isn't saved anywhere.  Once I found
commit 92316a4, I realized that data was actually stored in a separate hash
table.  In fact, many of the functions in this area don't actually need to
return anything, so we can trim some code and hopefully reduce confusion a
bit.  Patch attached.

[0] https://postgr.es/m/8F1F1E1D-D17B-4B33-B014-EDBCD15F3F0B%40yesql.se

-- 
nathan

From a6b8585cd55c0758ffb1cabb4c4deacbb65af9d3 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <[email protected]>
Date: Tue, 4 Jun 2024 22:32:20 -0500
Subject: [PATCH v1 1/1] Trim some unnecessary pg_dump code.

---
 src/bin/pg_dump/common.c  |  69 ++++------
 src/bin/pg_dump/pg_dump.c | 282 +++++++++-----------------------------
 src/bin/pg_dump/pg_dump.h |  49 ++++---
 3 files changed, 113 insertions(+), 287 deletions(-)

diff --git a/src/bin/pg_dump/common.c b/src/bin/pg_dump/common.c
index 64e7dc89f1..c323b5bd3d 100644
--- a/src/bin/pg_dump/common.c
+++ b/src/bin/pg_dump/common.c
@@ -101,31 +101,8 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	ExtensionInfo *extinfo;
 	InhInfo    *inhinfo;
 	int			numTables;
-	int			numTypes;
-	int			numFuncs;
-	int			numOperators;
-	int			numCollations;
-	int			numNamespaces;
 	int			numExtensions;
-	int			numPublications;
-	int			numAggregates;
 	int			numInherits;
-	int			numRules;
-	int			numProcLangs;
-	int			numCasts;
-	int			numTransforms;
-	int			numAccessMethods;
-	int			numOpclasses;
-	int			numOpfamilies;
-	int			numConversions;
-	int			numTSParsers;
-	int			numTSTemplates;
-	int			numTSDicts;
-	int			numTSConfigs;
-	int			numForeignDataWrappers;
-	int			numForeignServers;
-	int			numDefaultACLs;
-	int			numEventTriggers;
 
 	/*
 	 * We must read extensions and extension membership info first, because
@@ -139,7 +116,7 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	getExtensionMembership(fout, extinfo, numExtensions);
 
 	pg_log_info("reading schemas");
-	(void) getNamespaces(fout, &numNamespaces);
+	getNamespaces(fout);
 
 	/*
 	 * getTables should be done as soon as possible, so as to minimize the
@@ -153,69 +130,69 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	getOwnedSeqs(fout, tblinfo, numTables);
 
 	pg_log_info("reading user-defined functions");
-	(void) getFuncs(fout, &numFuncs);
+	getFuncs(fout);
 
 	/* this must be after getTables and getFuncs */
 	pg_log_info("reading user-defined types");
-	(void) getTypes(fout, &numTypes);
+	getTypes(fout);
 
 	/* this must be after getFuncs, too */
 	pg_log_info("reading procedural languages");
-	getProcLangs(fout, &numProcLangs);
+	getProcLangs(fout);
 
 	pg_log_info("reading user-defined aggregate functions");
-	getAggregates(fout, &numAggregates);
+	getAggregates(fout);
 
 	pg_log_info("reading user-defined operators");
-	(void) getOperators(fout, &numOperators);
+	getOperators(fout);
 
 	pg_log_info("reading user-defined access methods");
-	getAccessMethods(fout, &numAccessMethods);
+	getAccessMethods(fout);
 
 	pg_log_info("reading user-defined operator classes");
-	getOpclasses(fout, &numOpclasses);
+	getOpclasses(fout);
 
 	pg_log_info("reading user-defined operator families");
-	getOpfamilies(fout, &numOpfamilies);
+	getOpfamilies(fout);
 
 	pg_log_info("reading user-defined text search parsers");
-	getTSParsers(fout, &numTSParsers);
+	getTSParsers(fout);
 
 	pg_log_info("reading user-defined text search templates");
-	getTSTemplates(fout, &numTSTemplates);
+	getTSTemplates(fout);
 
 	pg_log_info("reading user-defined text search dictionaries");
-	getTSDictionaries(fout, &numTSDicts);
+	getTSDictionaries(fout);
 
 	pg_log_info("reading user-defined text search configurations");
-	getTSConfigurations(fout, &numTSConfigs);
+	getTSConfigurations(fout);
 
 	pg_log_info("reading user-defined foreign-data wrappers");
-	getForeignDataWrappers(fout, &numForeignDataWrappers);
+	getForeignDataWrappers(fout);
 
 	pg_log_info("reading user-defined foreign servers");
-	getForeignServers(fout, &numForeignServers);
+	getForeignServers(fout);
 
 	pg_log_info("reading default privileges");
-	getDefaultACLs(fout, &numDefaultACLs);
+	getDefaultACLs(fout);
 
 	pg_log_info("reading user-defined collations");
-	(void) getCollations(fout, &numCollations);
+	getCollations(fout);
 
 	pg_log_info("reading user-defined conversions");
-	getConversions(fout, &numConversions);
+	getConversions(fout);
 
 	pg_log_info("reading type casts");
-	getCasts(fout, &numCasts);
+	getCasts(fout);
 
 	pg_log_info("reading transforms");
-	getTransforms(fout, &numTransforms);
+	getTransforms(fout);
 
 	pg_log_info("reading table inheritance information");
 	inhinfo = getInherits(fout, &numInherits);
 
 	pg_log_info("reading event triggers");
-	getEventTriggers(fout, &numEventTriggers);
+	getEventTriggers(fout);
 
 	/* Identify extension configuration tables that should be dumped */
 	pg_log_info("finding extension tables");
@@ -250,13 +227,13 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	getTriggers(fout, tblinfo, numTables);
 
 	pg_log_info("reading rewrite rules");
-	getRules(fout, &numRules);
+	getRules(fout);
 
 	pg_log_info("reading policies");
 	getPolicies(fout, tblinfo, numTables);
 
 	pg_log_info("reading publications");
-	(void) getPublications(fout, &numPublications);
+	getPublications(fout);
 
 	pg_log_info("reading publication membership of tables");
 	getPublicationTables(fout, tblinfo, numTables);
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index e324070828..7aec016a9f 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -4173,8 +4173,8 @@ dumpPolicy(Archive *fout, const PolicyInfo *polinfo)
  * getPublications
  *	  get information about publications
  */
-PublicationInfo *
-getPublications(Archive *fout, int *numPublications)
+void
+getPublications(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	PQExpBuffer query;
@@ -4194,10 +4194,7 @@ getPublications(Archive *fout, int *numPublications)
 				ntups;
 
 	if (dopt->no_publications || fout->remoteVersion < 100000)
-	{
-		*numPublications = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -4268,9 +4265,6 @@ getPublications(Archive *fout, int *numPublications)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	*numPublications = ntups;
-	return pubinfo;
 }
 
 /*
@@ -5547,13 +5541,10 @@ binary_upgrade_extension_member(PQExpBuffer upgrade_buffer,
 
 /*
  * getNamespaces:
- *	  read all namespaces in the system catalogs and return them in the
- * NamespaceInfo* structure
- *
- *	numNamespaces is set to the number of namespaces read in
+ *	  get information about all namespaces in the system catalogs
  */
-NamespaceInfo *
-getNamespaces(Archive *fout, int *numNamespaces)
+void
+getNamespaces(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -5660,10 +5651,6 @@ getNamespaces(Archive *fout, int *numNamespaces)
 
 	PQclear(res);
 	destroyPQExpBuffer(query);
-
-	*numNamespaces = ntups;
-
-	return nsinfo;
 }
 
 /*
@@ -5755,16 +5742,13 @@ getExtensions(Archive *fout, int *numExtensions)
 
 /*
  * getTypes:
- *	  read all types in the system catalogs and return them in the
- * TypeInfo* structure
- *
- *	numTypes is set to the number of types read in
+ *	  get information about all types in the system catalogs
  *
  * NB: this must run after getFuncs() because we assume we can do
  * findFuncByOid().
  */
-TypeInfo *
-getTypes(Archive *fout, int *numTypes)
+void
+getTypes(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -5917,24 +5901,17 @@ getTypes(Archive *fout, int *numTypes)
 		}
 	}
 
-	*numTypes = ntups;
-
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return tyinfo;
 }
 
 /*
  * getOperators:
- *	  read all operators in the system catalogs and return them in the
- * OprInfo* structure
- *
- *	numOprs is set to the number of operators read in
+ *	  get information about all operators in the system catalogs
  */
-OprInfo *
-getOperators(Archive *fout, int *numOprs)
+void
+getOperators(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -5964,7 +5941,6 @@ getOperators(Archive *fout, int *numOprs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numOprs = ntups;
 
 	oprinfo = (OprInfo *) pg_malloc(ntups * sizeof(OprInfo));
 
@@ -5996,19 +5972,14 @@ getOperators(Archive *fout, int *numOprs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return oprinfo;
 }
 
 /*
  * getCollations:
- *	  read all collations in the system catalogs and return them in the
- * CollInfo* structure
- *
- *	numCollations is set to the number of collations read in
+ *	  get information about all collations in the system catalogs
  */
-CollInfo *
-getCollations(Archive *fout, int *numCollations)
+void
+getCollations(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6036,7 +6007,6 @@ getCollations(Archive *fout, int *numCollations)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numCollations = ntups;
 
 	collinfo = (CollInfo *) pg_malloc(ntups * sizeof(CollInfo));
 
@@ -6064,19 +6034,14 @@ getCollations(Archive *fout, int *numCollations)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return collinfo;
 }
 
 /*
  * getConversions:
- *	  read all conversions in the system catalogs and return them in the
- * ConvInfo* structure
- *
- *	numConversions is set to the number of conversions read in
+ *	  get information about all conversions in the system catalogs
  */
-ConvInfo *
-getConversions(Archive *fout, int *numConversions)
+void
+getConversions(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6104,7 +6069,6 @@ getConversions(Archive *fout, int *numConversions)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numConversions = ntups;
 
 	convinfo = (ConvInfo *) pg_malloc(ntups * sizeof(ConvInfo));
 
@@ -6132,19 +6096,14 @@ getConversions(Archive *fout, int *numConversions)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return convinfo;
 }
 
 /*
  * getAccessMethods:
- *	  read all user-defined access methods in the system catalogs and return
- *	  them in the AccessMethodInfo* structure
- *
- *	numAccessMethods is set to the number of access methods read in
+ *	  get information about all user-defined access methods
  */
-AccessMethodInfo *
-getAccessMethods(Archive *fout, int *numAccessMethods)
+void
+getAccessMethods(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6159,10 +6118,7 @@ getAccessMethods(Archive *fout, int *numAccessMethods)
 
 	/* Before 9.6, there are no user-defined access methods */
 	if (fout->remoteVersion < 90600)
-	{
-		*numAccessMethods = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -6174,7 +6130,6 @@ getAccessMethods(Archive *fout, int *numAccessMethods)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numAccessMethods = ntups;
 
 	aminfo = (AccessMethodInfo *) pg_malloc(ntups * sizeof(AccessMethodInfo));
 
@@ -6202,20 +6157,15 @@ getAccessMethods(Archive *fout, int *numAccessMethods)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return aminfo;
 }
 
 
 /*
  * getOpclasses:
- *	  read all opclasses in the system catalogs and return them in the
- * OpclassInfo* structure
- *
- *	numOpclasses is set to the number of opclasses read in
+ *	  get information about all opclasses in the system catalogs
  */
-OpclassInfo *
-getOpclasses(Archive *fout, int *numOpclasses)
+void
+getOpclasses(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6241,7 +6191,6 @@ getOpclasses(Archive *fout, int *numOpclasses)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numOpclasses = ntups;
 
 	opcinfo = (OpclassInfo *) pg_malloc(ntups * sizeof(OpclassInfo));
 
@@ -6269,19 +6218,14 @@ getOpclasses(Archive *fout, int *numOpclasses)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return opcinfo;
 }
 
 /*
  * getOpfamilies:
- *	  read all opfamilies in the system catalogs and return them in the
- * OpfamilyInfo* structure
- *
- *	numOpfamilies is set to the number of opfamilies read in
+ *	  get information about all opfamilies in the system catalogs
  */
-OpfamilyInfo *
-getOpfamilies(Archive *fout, int *numOpfamilies)
+void
+getOpfamilies(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6309,7 +6253,6 @@ getOpfamilies(Archive *fout, int *numOpfamilies)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numOpfamilies = ntups;
 
 	opfinfo = (OpfamilyInfo *) pg_malloc(ntups * sizeof(OpfamilyInfo));
 
@@ -6337,19 +6280,14 @@ getOpfamilies(Archive *fout, int *numOpfamilies)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return opfinfo;
 }
 
 /*
  * getAggregates:
- *	  read all the user-defined aggregates in the system catalogs and
- * return them in the AggInfo* structure
- *
- * numAggs is set to the number of aggregates read in
+ *	  get information about all user-defined aggregates in the system catalogs
  */
-AggInfo *
-getAggregates(Archive *fout, int *numAggs)
+void
+getAggregates(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	PGresult   *res;
@@ -6431,7 +6369,6 @@ getAggregates(Archive *fout, int *numAggs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numAggs = ntups;
 
 	agginfo = (AggInfo *) pg_malloc(ntups * sizeof(AggInfo));
 
@@ -6484,19 +6421,14 @@ getAggregates(Archive *fout, int *numAggs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return agginfo;
 }
 
 /*
  * getFuncs:
- *	  read all the user-defined functions in the system catalogs and
- * return them in the FuncInfo* structure
- *
- * numFuncs is set to the number of functions read in
+ *	  get information about all user-defined functions in the system catalogs
  */
-FuncInfo *
-getFuncs(Archive *fout, int *numFuncs)
+void
+getFuncs(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	PGresult   *res;
@@ -6629,8 +6561,6 @@ getFuncs(Archive *fout, int *numFuncs)
 
 	ntups = PQntuples(res);
 
-	*numFuncs = ntups;
-
 	finfo = (FuncInfo *) pg_malloc0(ntups * sizeof(FuncInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -6683,8 +6613,6 @@ getFuncs(Archive *fout, int *numFuncs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return finfo;
 }
 
 /*
@@ -7985,11 +7913,9 @@ getDomainConstraints(Archive *fout, TypeInfo *tyinfo)
 /*
  * getRules
  *	  get basic information about every rule in the system
- *
- * numRules is set to the number of rules read in
  */
-RuleInfo *
-getRules(Archive *fout, int *numRules)
+void
+getRules(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8015,8 +7941,6 @@ getRules(Archive *fout, int *numRules)
 
 	ntups = PQntuples(res);
 
-	*numRules = ntups;
-
 	ruleinfo = (RuleInfo *) pg_malloc(ntups * sizeof(RuleInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8078,8 +8002,6 @@ getRules(Archive *fout, int *numRules)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return ruleinfo;
 }
 
 /*
@@ -8285,8 +8207,8 @@ getTriggers(Archive *fout, TableInfo tblinfo[], int numTables)
  * getEventTriggers
  *	  get information about event triggers
  */
-EventTriggerInfo *
-getEventTriggers(Archive *fout, int *numEventTriggers)
+void
+getEventTriggers(Archive *fout)
 {
 	int			i;
 	PQExpBuffer query;
@@ -8304,10 +8226,7 @@ getEventTriggers(Archive *fout, int *numEventTriggers)
 
 	/* Before 9.3, there are no event triggers */
 	if (fout->remoteVersion < 90300)
-	{
-		*numEventTriggers = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -8325,8 +8244,6 @@ getEventTriggers(Archive *fout, int *numEventTriggers)
 
 	ntups = PQntuples(res);
 
-	*numEventTriggers = ntups;
-
 	evtinfo = (EventTriggerInfo *) pg_malloc(ntups * sizeof(EventTriggerInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8359,21 +8276,17 @@ getEventTriggers(Archive *fout, int *numEventTriggers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return evtinfo;
 }
 
 /*
  * getProcLangs
  *	  get basic information about every procedural language in the system
  *
- * numProcLangs is set to the number of langs read in
- *
  * NB: this must run after getFuncs() because we assume we can do
  * findFuncByOid().
  */
-ProcLangInfo *
-getProcLangs(Archive *fout, int *numProcLangs)
+void
+getProcLangs(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8405,8 +8318,6 @@ getProcLangs(Archive *fout, int *numProcLangs)
 
 	ntups = PQntuples(res);
 
-	*numProcLangs = ntups;
-
 	planginfo = (ProcLangInfo *) pg_malloc(ntups * sizeof(ProcLangInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8449,21 +8360,17 @@ getProcLangs(Archive *fout, int *numProcLangs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return planginfo;
 }
 
 /*
  * getCasts
  *	  get basic information about most casts in the system
  *
- * numCasts is set to the number of casts read in
- *
  * Skip casts from a range to its multirange, since we'll create those
  * automatically.
  */
-CastInfo *
-getCasts(Archive *fout, int *numCasts)
+void
+getCasts(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8503,8 +8410,6 @@ getCasts(Archive *fout, int *numCasts)
 
 	ntups = PQntuples(res);
 
-	*numCasts = ntups;
-
 	castinfo = (CastInfo *) pg_malloc(ntups * sizeof(CastInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8551,8 +8456,6 @@ getCasts(Archive *fout, int *numCasts)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return castinfo;
 }
 
 static char *
@@ -8575,11 +8478,9 @@ get_language_name(Archive *fout, Oid langid)
 /*
  * getTransforms
  *	  get basic information about every transform in the system
- *
- * numTransforms is set to the number of transforms read in
  */
-TransformInfo *
-getTransforms(Archive *fout, int *numTransforms)
+void
+getTransforms(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8595,10 +8496,7 @@ getTransforms(Archive *fout, int *numTransforms)
 
 	/* Transforms didn't exist pre-9.5 */
 	if (fout->remoteVersion < 90500)
-	{
-		*numTransforms = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -8611,8 +8509,6 @@ getTransforms(Archive *fout, int *numTransforms)
 
 	ntups = PQntuples(res);
 
-	*numTransforms = ntups;
-
 	transforminfo = (TransformInfo *) pg_malloc(ntups * sizeof(TransformInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8658,8 +8554,6 @@ getTransforms(Archive *fout, int *numTransforms)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return transforminfo;
 }
 
 /*
@@ -9239,13 +9133,10 @@ shouldPrintColumn(const DumpOptions *dopt, const TableInfo *tbinfo, int colno)
 
 /*
  * getTSParsers:
- *	  read all text search parsers in the system catalogs and return them
- *	  in the TSParserInfo* structure
- *
- *	numTSParsers is set to the number of parsers read in
+ *	  get information about all text search parsers in the system catalogs
  */
-TSParserInfo *
-getTSParsers(Archive *fout, int *numTSParsers)
+void
+getTSParsers(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9277,7 +9168,6 @@ getTSParsers(Archive *fout, int *numTSParsers)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSParsers = ntups;
 
 	prsinfo = (TSParserInfo *) pg_malloc(ntups * sizeof(TSParserInfo));
 
@@ -9313,19 +9203,14 @@ getTSParsers(Archive *fout, int *numTSParsers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return prsinfo;
 }
 
 /*
  * getTSDictionaries:
- *	  read all text search dictionaries in the system catalogs and return them
- *	  in the TSDictInfo* structure
- *
- *	numTSDicts is set to the number of dictionaries read in
+ *	  get information about all text search dictionaries in the system catalogs
  */
-TSDictInfo *
-getTSDictionaries(Archive *fout, int *numTSDicts)
+void
+getTSDictionaries(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9350,7 +9235,6 @@ getTSDictionaries(Archive *fout, int *numTSDicts)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSDicts = ntups;
 
 	dictinfo = (TSDictInfo *) pg_malloc(ntups * sizeof(TSDictInfo));
 
@@ -9385,19 +9269,14 @@ getTSDictionaries(Archive *fout, int *numTSDicts)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return dictinfo;
 }
 
 /*
  * getTSTemplates:
- *	  read all text search templates in the system catalogs and return them
- *	  in the TSTemplateInfo* structure
- *
- *	numTSTemplates is set to the number of templates read in
+ *	  get information about all text search templates in the system catalogs
  */
-TSTemplateInfo *
-getTSTemplates(Archive *fout, int *numTSTemplates)
+void
+getTSTemplates(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9420,7 +9299,6 @@ getTSTemplates(Archive *fout, int *numTSTemplates)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSTemplates = ntups;
 
 	tmplinfo = (TSTemplateInfo *) pg_malloc(ntups * sizeof(TSTemplateInfo));
 
@@ -9450,19 +9328,14 @@ getTSTemplates(Archive *fout, int *numTSTemplates)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return tmplinfo;
 }
 
 /*
  * getTSConfigurations:
- *	  read all text search configurations in the system catalogs and return
- *	  them in the TSConfigInfo* structure
- *
- *	numTSConfigs is set to the number of configurations read in
+ *	  get information about all text search configurations
  */
-TSConfigInfo *
-getTSConfigurations(Archive *fout, int *numTSConfigs)
+void
+getTSConfigurations(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9485,7 +9358,6 @@ getTSConfigurations(Archive *fout, int *numTSConfigs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSConfigs = ntups;
 
 	cfginfo = (TSConfigInfo *) pg_malloc(ntups * sizeof(TSConfigInfo));
 
@@ -9515,19 +9387,14 @@ getTSConfigurations(Archive *fout, int *numTSConfigs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return cfginfo;
 }
 
 /*
  * getForeignDataWrappers:
- *	  read all foreign-data wrappers in the system catalogs and return
- *	  them in the FdwInfo* structure
- *
- *	numForeignDataWrappers is set to the number of fdws read in
+ *	  get information about all foreign-data wrappers in the system catalogs
  */
-FdwInfo *
-getForeignDataWrappers(Archive *fout, int *numForeignDataWrappers)
+void
+getForeignDataWrappers(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9563,7 +9430,6 @@ getForeignDataWrappers(Archive *fout, int *numForeignDataWrappers)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numForeignDataWrappers = ntups;
 
 	fdwinfo = (FdwInfo *) pg_malloc(ntups * sizeof(FdwInfo));
 
@@ -9605,19 +9471,14 @@ getForeignDataWrappers(Archive *fout, int *numForeignDataWrappers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return fdwinfo;
 }
 
 /*
  * getForeignServers:
- *	  read all foreign servers in the system catalogs and return
- *	  them in the ForeignServerInfo * structure
- *
- *	numForeignServers is set to the number of servers read in
+ *	  get information about all foreign servers in the system catalogs
  */
-ForeignServerInfo *
-getForeignServers(Archive *fout, int *numForeignServers)
+void
+getForeignServers(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9652,7 +9513,6 @@ getForeignServers(Archive *fout, int *numForeignServers)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numForeignServers = ntups;
 
 	srvinfo = (ForeignServerInfo *) pg_malloc(ntups * sizeof(ForeignServerInfo));
 
@@ -9699,19 +9559,14 @@ getForeignServers(Archive *fout, int *numForeignServers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return srvinfo;
 }
 
 /*
  * getDefaultACLs:
- *	  read all default ACL information in the system catalogs and return
- *	  them in the DefaultACLInfo structure
- *
- *	numDefaultACLs is set to the number of ACLs read in
+ *	  get information about all default ACL information in the system catalogs
  */
-DefaultACLInfo *
-getDefaultACLs(Archive *fout, int *numDefaultACLs)
+void
+getDefaultACLs(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	DefaultACLInfo *daclinfo;
@@ -9756,7 +9611,6 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numDefaultACLs = ntups;
 
 	daclinfo = (DefaultACLInfo *) pg_malloc(ntups * sizeof(DefaultACLInfo));
 
@@ -9801,8 +9655,6 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return daclinfo;
 }
 
 /*
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index 865823868f..4b2e5870a9 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -731,17 +731,17 @@ extern void sortDumpableObjectsByTypeName(DumpableObject **objs, int numObjs);
 /*
  * version specific routines
  */
-extern NamespaceInfo *getNamespaces(Archive *fout, int *numNamespaces);
+extern void getNamespaces(Archive *fout);
 extern ExtensionInfo *getExtensions(Archive *fout, int *numExtensions);
-extern TypeInfo *getTypes(Archive *fout, int *numTypes);
-extern FuncInfo *getFuncs(Archive *fout, int *numFuncs);
-extern AggInfo *getAggregates(Archive *fout, int *numAggs);
-extern OprInfo *getOperators(Archive *fout, int *numOprs);
-extern AccessMethodInfo *getAccessMethods(Archive *fout, int *numAccessMethods);
-extern OpclassInfo *getOpclasses(Archive *fout, int *numOpclasses);
-extern OpfamilyInfo *getOpfamilies(Archive *fout, int *numOpfamilies);
-extern CollInfo *getCollations(Archive *fout, int *numCollations);
-extern ConvInfo *getConversions(Archive *fout, int *numConversions);
+extern void getTypes(Archive *fout);
+extern void getFuncs(Archive *fout);
+extern void getAggregates(Archive *fout);
+extern void getOperators(Archive *fout);
+extern void getAccessMethods(Archive *fout);
+extern void getOpclasses(Archive *fout);
+extern void getOpfamilies(Archive *fout);
+extern void getCollations(Archive *fout);
+extern void getConversions(Archive *fout);
 extern TableInfo *getTables(Archive *fout, int *numTables);
 extern void getOwnedSeqs(Archive *fout, TableInfo tblinfo[], int numTables);
 extern InhInfo *getInherits(Archive *fout, int *numInherits);
@@ -749,30 +749,27 @@ extern void getPartitioningInfo(Archive *fout);
 extern void getIndexes(Archive *fout, TableInfo tblinfo[], int numTables);
 extern void getExtendedStatistics(Archive *fout);
 extern void getConstraints(Archive *fout, TableInfo tblinfo[], int numTables);
-extern RuleInfo *getRules(Archive *fout, int *numRules);
+extern void getRules(Archive *fout);
 extern void getTriggers(Archive *fout, TableInfo tblinfo[], int numTables);
-extern ProcLangInfo *getProcLangs(Archive *fout, int *numProcLangs);
-extern CastInfo *getCasts(Archive *fout, int *numCasts);
-extern TransformInfo *getTransforms(Archive *fout, int *numTransforms);
+extern void getProcLangs(Archive *fout);
+extern void getCasts(Archive *fout);
+extern void getTransforms(Archive *fout);
 extern void getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables);
 extern bool shouldPrintColumn(const DumpOptions *dopt, const TableInfo *tbinfo, int colno);
-extern TSParserInfo *getTSParsers(Archive *fout, int *numTSParsers);
-extern TSDictInfo *getTSDictionaries(Archive *fout, int *numTSDicts);
-extern TSTemplateInfo *getTSTemplates(Archive *fout, int *numTSTemplates);
-extern TSConfigInfo *getTSConfigurations(Archive *fout, int *numTSConfigs);
-extern FdwInfo *getForeignDataWrappers(Archive *fout,
-									   int *numForeignDataWrappers);
-extern ForeignServerInfo *getForeignServers(Archive *fout,
-											int *numForeignServers);
-extern DefaultACLInfo *getDefaultACLs(Archive *fout, int *numDefaultACLs);
+extern void getTSParsers(Archive *fout);
+extern void getTSDictionaries(Archive *fout);
+extern void getTSTemplates(Archive *fout);
+extern void getTSConfigurations(Archive *fout);
+extern void getForeignDataWrappers(Archive *fout);
+extern void getForeignServers(Archive *fout);
+extern void getDefaultACLs(Archive *fout);
 extern void getExtensionMembership(Archive *fout, ExtensionInfo extinfo[],
 								   int numExtensions);
 extern void processExtensionTables(Archive *fout, ExtensionInfo extinfo[],
 								   int numExtensions);
-extern EventTriggerInfo *getEventTriggers(Archive *fout, int *numEventTriggers);
+extern void getEventTriggers(Archive *fout);
 extern void getPolicies(Archive *fout, TableInfo tblinfo[], int numTables);
-extern PublicationInfo *getPublications(Archive *fout,
-										int *numPublications);
+extern void getPublications(Archive *fout);
 extern void getPublicationNamespaces(Archive *fout);
 extern void getPublicationTables(Archive *fout, TableInfo tblinfo[],
 								 int numTables);
-- 
2.39.3 (Apple Git-146)



Attachments:

  [text/plain] v1-0001-Trim-some-unnecessary-pg_dump-code.patch (27.7K, ../../ZmCAtVaOrHpf31PJ@nathan/2-v1-0001-Trim-some-unnecessary-pg_dump-code.patch)
  download | inline diff:
From a6b8585cd55c0758ffb1cabb4c4deacbb65af9d3 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <[email protected]>
Date: Tue, 4 Jun 2024 22:32:20 -0500
Subject: [PATCH v1 1/1] Trim some unnecessary pg_dump code.

---
 src/bin/pg_dump/common.c  |  69 ++++------
 src/bin/pg_dump/pg_dump.c | 282 +++++++++-----------------------------
 src/bin/pg_dump/pg_dump.h |  49 ++++---
 3 files changed, 113 insertions(+), 287 deletions(-)

diff --git a/src/bin/pg_dump/common.c b/src/bin/pg_dump/common.c
index 64e7dc89f1..c323b5bd3d 100644
--- a/src/bin/pg_dump/common.c
+++ b/src/bin/pg_dump/common.c
@@ -101,31 +101,8 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	ExtensionInfo *extinfo;
 	InhInfo    *inhinfo;
 	int			numTables;
-	int			numTypes;
-	int			numFuncs;
-	int			numOperators;
-	int			numCollations;
-	int			numNamespaces;
 	int			numExtensions;
-	int			numPublications;
-	int			numAggregates;
 	int			numInherits;
-	int			numRules;
-	int			numProcLangs;
-	int			numCasts;
-	int			numTransforms;
-	int			numAccessMethods;
-	int			numOpclasses;
-	int			numOpfamilies;
-	int			numConversions;
-	int			numTSParsers;
-	int			numTSTemplates;
-	int			numTSDicts;
-	int			numTSConfigs;
-	int			numForeignDataWrappers;
-	int			numForeignServers;
-	int			numDefaultACLs;
-	int			numEventTriggers;
 
 	/*
 	 * We must read extensions and extension membership info first, because
@@ -139,7 +116,7 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	getExtensionMembership(fout, extinfo, numExtensions);
 
 	pg_log_info("reading schemas");
-	(void) getNamespaces(fout, &numNamespaces);
+	getNamespaces(fout);
 
 	/*
 	 * getTables should be done as soon as possible, so as to minimize the
@@ -153,69 +130,69 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	getOwnedSeqs(fout, tblinfo, numTables);
 
 	pg_log_info("reading user-defined functions");
-	(void) getFuncs(fout, &numFuncs);
+	getFuncs(fout);
 
 	/* this must be after getTables and getFuncs */
 	pg_log_info("reading user-defined types");
-	(void) getTypes(fout, &numTypes);
+	getTypes(fout);
 
 	/* this must be after getFuncs, too */
 	pg_log_info("reading procedural languages");
-	getProcLangs(fout, &numProcLangs);
+	getProcLangs(fout);
 
 	pg_log_info("reading user-defined aggregate functions");
-	getAggregates(fout, &numAggregates);
+	getAggregates(fout);
 
 	pg_log_info("reading user-defined operators");
-	(void) getOperators(fout, &numOperators);
+	getOperators(fout);
 
 	pg_log_info("reading user-defined access methods");
-	getAccessMethods(fout, &numAccessMethods);
+	getAccessMethods(fout);
 
 	pg_log_info("reading user-defined operator classes");
-	getOpclasses(fout, &numOpclasses);
+	getOpclasses(fout);
 
 	pg_log_info("reading user-defined operator families");
-	getOpfamilies(fout, &numOpfamilies);
+	getOpfamilies(fout);
 
 	pg_log_info("reading user-defined text search parsers");
-	getTSParsers(fout, &numTSParsers);
+	getTSParsers(fout);
 
 	pg_log_info("reading user-defined text search templates");
-	getTSTemplates(fout, &numTSTemplates);
+	getTSTemplates(fout);
 
 	pg_log_info("reading user-defined text search dictionaries");
-	getTSDictionaries(fout, &numTSDicts);
+	getTSDictionaries(fout);
 
 	pg_log_info("reading user-defined text search configurations");
-	getTSConfigurations(fout, &numTSConfigs);
+	getTSConfigurations(fout);
 
 	pg_log_info("reading user-defined foreign-data wrappers");
-	getForeignDataWrappers(fout, &numForeignDataWrappers);
+	getForeignDataWrappers(fout);
 
 	pg_log_info("reading user-defined foreign servers");
-	getForeignServers(fout, &numForeignServers);
+	getForeignServers(fout);
 
 	pg_log_info("reading default privileges");
-	getDefaultACLs(fout, &numDefaultACLs);
+	getDefaultACLs(fout);
 
 	pg_log_info("reading user-defined collations");
-	(void) getCollations(fout, &numCollations);
+	getCollations(fout);
 
 	pg_log_info("reading user-defined conversions");
-	getConversions(fout, &numConversions);
+	getConversions(fout);
 
 	pg_log_info("reading type casts");
-	getCasts(fout, &numCasts);
+	getCasts(fout);
 
 	pg_log_info("reading transforms");
-	getTransforms(fout, &numTransforms);
+	getTransforms(fout);
 
 	pg_log_info("reading table inheritance information");
 	inhinfo = getInherits(fout, &numInherits);
 
 	pg_log_info("reading event triggers");
-	getEventTriggers(fout, &numEventTriggers);
+	getEventTriggers(fout);
 
 	/* Identify extension configuration tables that should be dumped */
 	pg_log_info("finding extension tables");
@@ -250,13 +227,13 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	getTriggers(fout, tblinfo, numTables);
 
 	pg_log_info("reading rewrite rules");
-	getRules(fout, &numRules);
+	getRules(fout);
 
 	pg_log_info("reading policies");
 	getPolicies(fout, tblinfo, numTables);
 
 	pg_log_info("reading publications");
-	(void) getPublications(fout, &numPublications);
+	getPublications(fout);
 
 	pg_log_info("reading publication membership of tables");
 	getPublicationTables(fout, tblinfo, numTables);
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index e324070828..7aec016a9f 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -4173,8 +4173,8 @@ dumpPolicy(Archive *fout, const PolicyInfo *polinfo)
  * getPublications
  *	  get information about publications
  */
-PublicationInfo *
-getPublications(Archive *fout, int *numPublications)
+void
+getPublications(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	PQExpBuffer query;
@@ -4194,10 +4194,7 @@ getPublications(Archive *fout, int *numPublications)
 				ntups;
 
 	if (dopt->no_publications || fout->remoteVersion < 100000)
-	{
-		*numPublications = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -4268,9 +4265,6 @@ getPublications(Archive *fout, int *numPublications)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	*numPublications = ntups;
-	return pubinfo;
 }
 
 /*
@@ -5547,13 +5541,10 @@ binary_upgrade_extension_member(PQExpBuffer upgrade_buffer,
 
 /*
  * getNamespaces:
- *	  read all namespaces in the system catalogs and return them in the
- * NamespaceInfo* structure
- *
- *	numNamespaces is set to the number of namespaces read in
+ *	  get information about all namespaces in the system catalogs
  */
-NamespaceInfo *
-getNamespaces(Archive *fout, int *numNamespaces)
+void
+getNamespaces(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -5660,10 +5651,6 @@ getNamespaces(Archive *fout, int *numNamespaces)
 
 	PQclear(res);
 	destroyPQExpBuffer(query);
-
-	*numNamespaces = ntups;
-
-	return nsinfo;
 }
 
 /*
@@ -5755,16 +5742,13 @@ getExtensions(Archive *fout, int *numExtensions)
 
 /*
  * getTypes:
- *	  read all types in the system catalogs and return them in the
- * TypeInfo* structure
- *
- *	numTypes is set to the number of types read in
+ *	  get information about all types in the system catalogs
  *
  * NB: this must run after getFuncs() because we assume we can do
  * findFuncByOid().
  */
-TypeInfo *
-getTypes(Archive *fout, int *numTypes)
+void
+getTypes(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -5917,24 +5901,17 @@ getTypes(Archive *fout, int *numTypes)
 		}
 	}
 
-	*numTypes = ntups;
-
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return tyinfo;
 }
 
 /*
  * getOperators:
- *	  read all operators in the system catalogs and return them in the
- * OprInfo* structure
- *
- *	numOprs is set to the number of operators read in
+ *	  get information about all operators in the system catalogs
  */
-OprInfo *
-getOperators(Archive *fout, int *numOprs)
+void
+getOperators(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -5964,7 +5941,6 @@ getOperators(Archive *fout, int *numOprs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numOprs = ntups;
 
 	oprinfo = (OprInfo *) pg_malloc(ntups * sizeof(OprInfo));
 
@@ -5996,19 +5972,14 @@ getOperators(Archive *fout, int *numOprs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return oprinfo;
 }
 
 /*
  * getCollations:
- *	  read all collations in the system catalogs and return them in the
- * CollInfo* structure
- *
- *	numCollations is set to the number of collations read in
+ *	  get information about all collations in the system catalogs
  */
-CollInfo *
-getCollations(Archive *fout, int *numCollations)
+void
+getCollations(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6036,7 +6007,6 @@ getCollations(Archive *fout, int *numCollations)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numCollations = ntups;
 
 	collinfo = (CollInfo *) pg_malloc(ntups * sizeof(CollInfo));
 
@@ -6064,19 +6034,14 @@ getCollations(Archive *fout, int *numCollations)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return collinfo;
 }
 
 /*
  * getConversions:
- *	  read all conversions in the system catalogs and return them in the
- * ConvInfo* structure
- *
- *	numConversions is set to the number of conversions read in
+ *	  get information about all conversions in the system catalogs
  */
-ConvInfo *
-getConversions(Archive *fout, int *numConversions)
+void
+getConversions(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6104,7 +6069,6 @@ getConversions(Archive *fout, int *numConversions)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numConversions = ntups;
 
 	convinfo = (ConvInfo *) pg_malloc(ntups * sizeof(ConvInfo));
 
@@ -6132,19 +6096,14 @@ getConversions(Archive *fout, int *numConversions)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return convinfo;
 }
 
 /*
  * getAccessMethods:
- *	  read all user-defined access methods in the system catalogs and return
- *	  them in the AccessMethodInfo* structure
- *
- *	numAccessMethods is set to the number of access methods read in
+ *	  get information about all user-defined access methods
  */
-AccessMethodInfo *
-getAccessMethods(Archive *fout, int *numAccessMethods)
+void
+getAccessMethods(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6159,10 +6118,7 @@ getAccessMethods(Archive *fout, int *numAccessMethods)
 
 	/* Before 9.6, there are no user-defined access methods */
 	if (fout->remoteVersion < 90600)
-	{
-		*numAccessMethods = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -6174,7 +6130,6 @@ getAccessMethods(Archive *fout, int *numAccessMethods)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numAccessMethods = ntups;
 
 	aminfo = (AccessMethodInfo *) pg_malloc(ntups * sizeof(AccessMethodInfo));
 
@@ -6202,20 +6157,15 @@ getAccessMethods(Archive *fout, int *numAccessMethods)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return aminfo;
 }
 
 
 /*
  * getOpclasses:
- *	  read all opclasses in the system catalogs and return them in the
- * OpclassInfo* structure
- *
- *	numOpclasses is set to the number of opclasses read in
+ *	  get information about all opclasses in the system catalogs
  */
-OpclassInfo *
-getOpclasses(Archive *fout, int *numOpclasses)
+void
+getOpclasses(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6241,7 +6191,6 @@ getOpclasses(Archive *fout, int *numOpclasses)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numOpclasses = ntups;
 
 	opcinfo = (OpclassInfo *) pg_malloc(ntups * sizeof(OpclassInfo));
 
@@ -6269,19 +6218,14 @@ getOpclasses(Archive *fout, int *numOpclasses)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return opcinfo;
 }
 
 /*
  * getOpfamilies:
- *	  read all opfamilies in the system catalogs and return them in the
- * OpfamilyInfo* structure
- *
- *	numOpfamilies is set to the number of opfamilies read in
+ *	  get information about all opfamilies in the system catalogs
  */
-OpfamilyInfo *
-getOpfamilies(Archive *fout, int *numOpfamilies)
+void
+getOpfamilies(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -6309,7 +6253,6 @@ getOpfamilies(Archive *fout, int *numOpfamilies)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numOpfamilies = ntups;
 
 	opfinfo = (OpfamilyInfo *) pg_malloc(ntups * sizeof(OpfamilyInfo));
 
@@ -6337,19 +6280,14 @@ getOpfamilies(Archive *fout, int *numOpfamilies)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return opfinfo;
 }
 
 /*
  * getAggregates:
- *	  read all the user-defined aggregates in the system catalogs and
- * return them in the AggInfo* structure
- *
- * numAggs is set to the number of aggregates read in
+ *	  get information about all user-defined aggregates in the system catalogs
  */
-AggInfo *
-getAggregates(Archive *fout, int *numAggs)
+void
+getAggregates(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	PGresult   *res;
@@ -6431,7 +6369,6 @@ getAggregates(Archive *fout, int *numAggs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numAggs = ntups;
 
 	agginfo = (AggInfo *) pg_malloc(ntups * sizeof(AggInfo));
 
@@ -6484,19 +6421,14 @@ getAggregates(Archive *fout, int *numAggs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return agginfo;
 }
 
 /*
  * getFuncs:
- *	  read all the user-defined functions in the system catalogs and
- * return them in the FuncInfo* structure
- *
- * numFuncs is set to the number of functions read in
+ *	  get information about all user-defined functions in the system catalogs
  */
-FuncInfo *
-getFuncs(Archive *fout, int *numFuncs)
+void
+getFuncs(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	PGresult   *res;
@@ -6629,8 +6561,6 @@ getFuncs(Archive *fout, int *numFuncs)
 
 	ntups = PQntuples(res);
 
-	*numFuncs = ntups;
-
 	finfo = (FuncInfo *) pg_malloc0(ntups * sizeof(FuncInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -6683,8 +6613,6 @@ getFuncs(Archive *fout, int *numFuncs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return finfo;
 }
 
 /*
@@ -7985,11 +7913,9 @@ getDomainConstraints(Archive *fout, TypeInfo *tyinfo)
 /*
  * getRules
  *	  get basic information about every rule in the system
- *
- * numRules is set to the number of rules read in
  */
-RuleInfo *
-getRules(Archive *fout, int *numRules)
+void
+getRules(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8015,8 +7941,6 @@ getRules(Archive *fout, int *numRules)
 
 	ntups = PQntuples(res);
 
-	*numRules = ntups;
-
 	ruleinfo = (RuleInfo *) pg_malloc(ntups * sizeof(RuleInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8078,8 +8002,6 @@ getRules(Archive *fout, int *numRules)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return ruleinfo;
 }
 
 /*
@@ -8285,8 +8207,8 @@ getTriggers(Archive *fout, TableInfo tblinfo[], int numTables)
  * getEventTriggers
  *	  get information about event triggers
  */
-EventTriggerInfo *
-getEventTriggers(Archive *fout, int *numEventTriggers)
+void
+getEventTriggers(Archive *fout)
 {
 	int			i;
 	PQExpBuffer query;
@@ -8304,10 +8226,7 @@ getEventTriggers(Archive *fout, int *numEventTriggers)
 
 	/* Before 9.3, there are no event triggers */
 	if (fout->remoteVersion < 90300)
-	{
-		*numEventTriggers = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -8325,8 +8244,6 @@ getEventTriggers(Archive *fout, int *numEventTriggers)
 
 	ntups = PQntuples(res);
 
-	*numEventTriggers = ntups;
-
 	evtinfo = (EventTriggerInfo *) pg_malloc(ntups * sizeof(EventTriggerInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8359,21 +8276,17 @@ getEventTriggers(Archive *fout, int *numEventTriggers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return evtinfo;
 }
 
 /*
  * getProcLangs
  *	  get basic information about every procedural language in the system
  *
- * numProcLangs is set to the number of langs read in
- *
  * NB: this must run after getFuncs() because we assume we can do
  * findFuncByOid().
  */
-ProcLangInfo *
-getProcLangs(Archive *fout, int *numProcLangs)
+void
+getProcLangs(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8405,8 +8318,6 @@ getProcLangs(Archive *fout, int *numProcLangs)
 
 	ntups = PQntuples(res);
 
-	*numProcLangs = ntups;
-
 	planginfo = (ProcLangInfo *) pg_malloc(ntups * sizeof(ProcLangInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8449,21 +8360,17 @@ getProcLangs(Archive *fout, int *numProcLangs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return planginfo;
 }
 
 /*
  * getCasts
  *	  get basic information about most casts in the system
  *
- * numCasts is set to the number of casts read in
- *
  * Skip casts from a range to its multirange, since we'll create those
  * automatically.
  */
-CastInfo *
-getCasts(Archive *fout, int *numCasts)
+void
+getCasts(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8503,8 +8410,6 @@ getCasts(Archive *fout, int *numCasts)
 
 	ntups = PQntuples(res);
 
-	*numCasts = ntups;
-
 	castinfo = (CastInfo *) pg_malloc(ntups * sizeof(CastInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8551,8 +8456,6 @@ getCasts(Archive *fout, int *numCasts)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return castinfo;
 }
 
 static char *
@@ -8575,11 +8478,9 @@ get_language_name(Archive *fout, Oid langid)
 /*
  * getTransforms
  *	  get basic information about every transform in the system
- *
- * numTransforms is set to the number of transforms read in
  */
-TransformInfo *
-getTransforms(Archive *fout, int *numTransforms)
+void
+getTransforms(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -8595,10 +8496,7 @@ getTransforms(Archive *fout, int *numTransforms)
 
 	/* Transforms didn't exist pre-9.5 */
 	if (fout->remoteVersion < 90500)
-	{
-		*numTransforms = 0;
-		return NULL;
-	}
+		return;
 
 	query = createPQExpBuffer();
 
@@ -8611,8 +8509,6 @@ getTransforms(Archive *fout, int *numTransforms)
 
 	ntups = PQntuples(res);
 
-	*numTransforms = ntups;
-
 	transforminfo = (TransformInfo *) pg_malloc(ntups * sizeof(TransformInfo));
 
 	i_tableoid = PQfnumber(res, "tableoid");
@@ -8658,8 +8554,6 @@ getTransforms(Archive *fout, int *numTransforms)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return transforminfo;
 }
 
 /*
@@ -9239,13 +9133,10 @@ shouldPrintColumn(const DumpOptions *dopt, const TableInfo *tbinfo, int colno)
 
 /*
  * getTSParsers:
- *	  read all text search parsers in the system catalogs and return them
- *	  in the TSParserInfo* structure
- *
- *	numTSParsers is set to the number of parsers read in
+ *	  get information about all text search parsers in the system catalogs
  */
-TSParserInfo *
-getTSParsers(Archive *fout, int *numTSParsers)
+void
+getTSParsers(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9277,7 +9168,6 @@ getTSParsers(Archive *fout, int *numTSParsers)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSParsers = ntups;
 
 	prsinfo = (TSParserInfo *) pg_malloc(ntups * sizeof(TSParserInfo));
 
@@ -9313,19 +9203,14 @@ getTSParsers(Archive *fout, int *numTSParsers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return prsinfo;
 }
 
 /*
  * getTSDictionaries:
- *	  read all text search dictionaries in the system catalogs and return them
- *	  in the TSDictInfo* structure
- *
- *	numTSDicts is set to the number of dictionaries read in
+ *	  get information about all text search dictionaries in the system catalogs
  */
-TSDictInfo *
-getTSDictionaries(Archive *fout, int *numTSDicts)
+void
+getTSDictionaries(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9350,7 +9235,6 @@ getTSDictionaries(Archive *fout, int *numTSDicts)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSDicts = ntups;
 
 	dictinfo = (TSDictInfo *) pg_malloc(ntups * sizeof(TSDictInfo));
 
@@ -9385,19 +9269,14 @@ getTSDictionaries(Archive *fout, int *numTSDicts)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return dictinfo;
 }
 
 /*
  * getTSTemplates:
- *	  read all text search templates in the system catalogs and return them
- *	  in the TSTemplateInfo* structure
- *
- *	numTSTemplates is set to the number of templates read in
+ *	  get information about all text search templates in the system catalogs
  */
-TSTemplateInfo *
-getTSTemplates(Archive *fout, int *numTSTemplates)
+void
+getTSTemplates(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9420,7 +9299,6 @@ getTSTemplates(Archive *fout, int *numTSTemplates)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSTemplates = ntups;
 
 	tmplinfo = (TSTemplateInfo *) pg_malloc(ntups * sizeof(TSTemplateInfo));
 
@@ -9450,19 +9328,14 @@ getTSTemplates(Archive *fout, int *numTSTemplates)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return tmplinfo;
 }
 
 /*
  * getTSConfigurations:
- *	  read all text search configurations in the system catalogs and return
- *	  them in the TSConfigInfo* structure
- *
- *	numTSConfigs is set to the number of configurations read in
+ *	  get information about all text search configurations
  */
-TSConfigInfo *
-getTSConfigurations(Archive *fout, int *numTSConfigs)
+void
+getTSConfigurations(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9485,7 +9358,6 @@ getTSConfigurations(Archive *fout, int *numTSConfigs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numTSConfigs = ntups;
 
 	cfginfo = (TSConfigInfo *) pg_malloc(ntups * sizeof(TSConfigInfo));
 
@@ -9515,19 +9387,14 @@ getTSConfigurations(Archive *fout, int *numTSConfigs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return cfginfo;
 }
 
 /*
  * getForeignDataWrappers:
- *	  read all foreign-data wrappers in the system catalogs and return
- *	  them in the FdwInfo* structure
- *
- *	numForeignDataWrappers is set to the number of fdws read in
+ *	  get information about all foreign-data wrappers in the system catalogs
  */
-FdwInfo *
-getForeignDataWrappers(Archive *fout, int *numForeignDataWrappers)
+void
+getForeignDataWrappers(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9563,7 +9430,6 @@ getForeignDataWrappers(Archive *fout, int *numForeignDataWrappers)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numForeignDataWrappers = ntups;
 
 	fdwinfo = (FdwInfo *) pg_malloc(ntups * sizeof(FdwInfo));
 
@@ -9605,19 +9471,14 @@ getForeignDataWrappers(Archive *fout, int *numForeignDataWrappers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return fdwinfo;
 }
 
 /*
  * getForeignServers:
- *	  read all foreign servers in the system catalogs and return
- *	  them in the ForeignServerInfo * structure
- *
- *	numForeignServers is set to the number of servers read in
+ *	  get information about all foreign servers in the system catalogs
  */
-ForeignServerInfo *
-getForeignServers(Archive *fout, int *numForeignServers)
+void
+getForeignServers(Archive *fout)
 {
 	PGresult   *res;
 	int			ntups;
@@ -9652,7 +9513,6 @@ getForeignServers(Archive *fout, int *numForeignServers)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numForeignServers = ntups;
 
 	srvinfo = (ForeignServerInfo *) pg_malloc(ntups * sizeof(ForeignServerInfo));
 
@@ -9699,19 +9559,14 @@ getForeignServers(Archive *fout, int *numForeignServers)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return srvinfo;
 }
 
 /*
  * getDefaultACLs:
- *	  read all default ACL information in the system catalogs and return
- *	  them in the DefaultACLInfo structure
- *
- *	numDefaultACLs is set to the number of ACLs read in
+ *	  get information about all default ACL information in the system catalogs
  */
-DefaultACLInfo *
-getDefaultACLs(Archive *fout, int *numDefaultACLs)
+void
+getDefaultACLs(Archive *fout)
 {
 	DumpOptions *dopt = fout->dopt;
 	DefaultACLInfo *daclinfo;
@@ -9756,7 +9611,6 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
 	ntups = PQntuples(res);
-	*numDefaultACLs = ntups;
 
 	daclinfo = (DefaultACLInfo *) pg_malloc(ntups * sizeof(DefaultACLInfo));
 
@@ -9801,8 +9655,6 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 	PQclear(res);
 
 	destroyPQExpBuffer(query);
-
-	return daclinfo;
 }
 
 /*
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index 865823868f..4b2e5870a9 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -731,17 +731,17 @@ extern void sortDumpableObjectsByTypeName(DumpableObject **objs, int numObjs);
 /*
  * version specific routines
  */
-extern NamespaceInfo *getNamespaces(Archive *fout, int *numNamespaces);
+extern void getNamespaces(Archive *fout);
 extern ExtensionInfo *getExtensions(Archive *fout, int *numExtensions);
-extern TypeInfo *getTypes(Archive *fout, int *numTypes);
-extern FuncInfo *getFuncs(Archive *fout, int *numFuncs);
-extern AggInfo *getAggregates(Archive *fout, int *numAggs);
-extern OprInfo *getOperators(Archive *fout, int *numOprs);
-extern AccessMethodInfo *getAccessMethods(Archive *fout, int *numAccessMethods);
-extern OpclassInfo *getOpclasses(Archive *fout, int *numOpclasses);
-extern OpfamilyInfo *getOpfamilies(Archive *fout, int *numOpfamilies);
-extern CollInfo *getCollations(Archive *fout, int *numCollations);
-extern ConvInfo *getConversions(Archive *fout, int *numConversions);
+extern void getTypes(Archive *fout);
+extern void getFuncs(Archive *fout);
+extern void getAggregates(Archive *fout);
+extern void getOperators(Archive *fout);
+extern void getAccessMethods(Archive *fout);
+extern void getOpclasses(Archive *fout);
+extern void getOpfamilies(Archive *fout);
+extern void getCollations(Archive *fout);
+extern void getConversions(Archive *fout);
 extern TableInfo *getTables(Archive *fout, int *numTables);
 extern void getOwnedSeqs(Archive *fout, TableInfo tblinfo[], int numTables);
 extern InhInfo *getInherits(Archive *fout, int *numInherits);
@@ -749,30 +749,27 @@ extern void getPartitioningInfo(Archive *fout);
 extern void getIndexes(Archive *fout, TableInfo tblinfo[], int numTables);
 extern void getExtendedStatistics(Archive *fout);
 extern void getConstraints(Archive *fout, TableInfo tblinfo[], int numTables);
-extern RuleInfo *getRules(Archive *fout, int *numRules);
+extern void getRules(Archive *fout);
 extern void getTriggers(Archive *fout, TableInfo tblinfo[], int numTables);
-extern ProcLangInfo *getProcLangs(Archive *fout, int *numProcLangs);
-extern CastInfo *getCasts(Archive *fout, int *numCasts);
-extern TransformInfo *getTransforms(Archive *fout, int *numTransforms);
+extern void getProcLangs(Archive *fout);
+extern void getCasts(Archive *fout);
+extern void getTransforms(Archive *fout);
 extern void getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables);
 extern bool shouldPrintColumn(const DumpOptions *dopt, const TableInfo *tbinfo, int colno);
-extern TSParserInfo *getTSParsers(Archive *fout, int *numTSParsers);
-extern TSDictInfo *getTSDictionaries(Archive *fout, int *numTSDicts);
-extern TSTemplateInfo *getTSTemplates(Archive *fout, int *numTSTemplates);
-extern TSConfigInfo *getTSConfigurations(Archive *fout, int *numTSConfigs);
-extern FdwInfo *getForeignDataWrappers(Archive *fout,
-									   int *numForeignDataWrappers);
-extern ForeignServerInfo *getForeignServers(Archive *fout,
-											int *numForeignServers);
-extern DefaultACLInfo *getDefaultACLs(Archive *fout, int *numDefaultACLs);
+extern void getTSParsers(Archive *fout);
+extern void getTSDictionaries(Archive *fout);
+extern void getTSTemplates(Archive *fout);
+extern void getTSConfigurations(Archive *fout);
+extern void getForeignDataWrappers(Archive *fout);
+extern void getForeignServers(Archive *fout);
+extern void getDefaultACLs(Archive *fout);
 extern void getExtensionMembership(Archive *fout, ExtensionInfo extinfo[],
 								   int numExtensions);
 extern void processExtensionTables(Archive *fout, ExtensionInfo extinfo[],
 								   int numExtensions);
-extern EventTriggerInfo *getEventTriggers(Archive *fout, int *numEventTriggers);
+extern void getEventTriggers(Archive *fout);
 extern void getPolicies(Archive *fout, TableInfo tblinfo[], int numTables);
-extern PublicationInfo *getPublications(Archive *fout,
-										int *numPublications);
+extern void getPublications(Archive *fout);
 extern void getPublicationNamespaces(Archive *fout);
 extern void getPublicationTables(Archive *fout, TableInfo tblinfo[],
 								 int numTables);
-- 
2.39.3 (Apple Git-146)



^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* Re: small pg_dump code cleanup
@ 2024-06-05 16:22  Neil Conway <[email protected]>
  parent: Nathan Bossart <[email protected]>
  0 siblings, 1 reply; 236+ messages in thread

From: Neil Conway @ 2024-06-05 16:22 UTC (permalink / raw)
  To: Nathan Bossart <[email protected]>; +Cc: pgsql-hackers

On Wed, Jun 5, 2024 at 11:14 AM Nathan Bossart <[email protected]>
wrote:

>  In fact, many of the functions in this area don't actually need to

return anything, so we can trim some code and hopefully reduce confusion a
> bit.  Patch attached.
>

Nice cleanup! Two minor comments:

(1) Names like `getXXX` for these functions suggest to me that they return
a value, rather than side-effecting. I realize some variants continue to
return a value, but the majority no longer do. Perhaps a name like
lookupXXX() or readXXX() would be clearer?

(2) These functions malloc() a single ntups * sizeof(struct) allocation and
then index into it to fill-in each struct before entering it into the hash
table. It might be more straightforward to just malloc each individual
struct.

Neil

^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* Re: small pg_dump code cleanup
@ 2024-06-05 16:37  Nathan Bossart <[email protected]>
  parent: Neil Conway <[email protected]>
  0 siblings, 2 replies; 236+ messages in thread

From: Nathan Bossart @ 2024-06-05 16:37 UTC (permalink / raw)
  To: Neil Conway <[email protected]>; +Cc: pgsql-hackers

On Wed, Jun 05, 2024 at 12:22:03PM -0400, Neil Conway wrote:
> Nice cleanup! Two minor comments:

Thanks for taking a look.

> (1) Names like `getXXX` for these functions suggest to me that they return
> a value, rather than side-effecting. I realize some variants continue to
> return a value, but the majority no longer do. Perhaps a name like
> lookupXXX() or readXXX() would be clearer?

What about collectXXX() to match similar functions in pg_dump.c (e.g.,
collectRoleNames(), collectComments(), collectSecLabels())?

> (2) These functions malloc() a single ntups * sizeof(struct) allocation and
> then index into it to fill-in each struct before entering it into the hash
> table. It might be more straightforward to just malloc each individual
> struct.

That'd increase the number of allocations quite significantly, but I'd be
surprised if that was noticeable outside of extreme scenarios.  At the
moment, I'm inclined to leave these as-is for this reason and because I
doubt it'd result in much cleanup, but I'll yield to the majority opinion
here.

-- 
nathan

^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* Re: small pg_dump code cleanup
@ 2024-06-05 17:51  Neil Conway <[email protected]>
  parent: Nathan Bossart <[email protected]>
  1 sibling, 0 replies; 236+ messages in thread

From: Neil Conway @ 2024-06-05 17:51 UTC (permalink / raw)
  To: Nathan Bossart <[email protected]>; +Cc: pgsql-hackers

On Wed, Jun 5, 2024 at 12:37 PM Nathan Bossart <[email protected]>
wrote:

> What about collectXXX() to match similar functions in pg_dump.c (e.g.,
> collectRoleNames(), collectComments(), collectSecLabels())?
>

sgtm.


> > (2) These functions malloc() a single ntups * sizeof(struct) allocation
> and
> > then index into it to fill-in each struct before entering it into the
> hash
> > table. It might be more straightforward to just malloc each individual
> > struct.
>
> That'd increase the number of allocations quite significantly, but I'd be
> surprised if that was noticeable outside of extreme scenarios.  At the
> moment, I'm inclined to leave these as-is for this reason and because I
> doubt it'd result in much cleanup, but I'll yield to the majority opinion
> here.
>

As you say, I'd be surprised if the performance difference is noticeable.
Personally I don't think the marginal performance win justifies the hit to
readability, but I don't feel strongly about it.

Neil


^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* Re: small pg_dump code cleanup
@ 2024-06-05 17:58  Tom Lane <[email protected]>
  parent: Nathan Bossart <[email protected]>
  1 sibling, 1 reply; 236+ messages in thread

From: Tom Lane @ 2024-06-05 17:58 UTC (permalink / raw)
  To: Nathan Bossart <[email protected]>; +Cc: Neil Conway <[email protected]>; pgsql-hackers

Nathan Bossart <[email protected]> writes:
> On Wed, Jun 05, 2024 at 12:22:03PM -0400, Neil Conway wrote:
>> (1) Names like `getXXX` for these functions suggest to me that they return
>> a value, rather than side-effecting. I realize some variants continue to
>> return a value, but the majority no longer do. Perhaps a name like
>> lookupXXX() or readXXX() would be clearer?

> What about collectXXX() to match similar functions in pg_dump.c (e.g.,
> collectRoleNames(), collectComments(), collectSecLabels())?

Personally I see nothing much wrong with leaving them as getXXX.

>> (2) These functions malloc() a single ntups * sizeof(struct) allocation and
>> then index into it to fill-in each struct before entering it into the hash
>> table. It might be more straightforward to just malloc each individual
>> struct.

> That'd increase the number of allocations quite significantly, but I'd be
> surprised if that was noticeable outside of extreme scenarios.  At the
> moment, I'm inclined to leave these as-is for this reason and because I
> doubt it'd result in much cleanup, but I'll yield to the majority opinion
> here.

I think that would be quite an invasive change; it would require
many hundreds of edits like

-		finfo[i].dobj.objType = DO_FUNC;
+		finfo->dobj.objType = DO_FUNC;

which aside from being tedious would create a back-patching hazard.
So I'm kind of -0.1 or so.

Another angle to this is that Coverity and possibly other tools tend
to report that these functions leak these allocations, apparently
because they don't notice that pointers into the allocations get
stored in hash tables by a subroutine.  I'm not sure if making this
change would make that worse or better.  If we really want to change
it, that might be worth checking somehow before we jump.

			regards, tom lane






^ permalink  raw  reply  [nested|flat] 236+ messages in thread

* Re: small pg_dump code cleanup
@ 2024-06-11 20:30  Nathan Bossart <[email protected]>
  parent: Tom Lane <[email protected]>
  0 siblings, 0 replies; 236+ messages in thread

From: Nathan Bossart @ 2024-06-11 20:30 UTC (permalink / raw)
  To: Tom Lane <[email protected]>; +Cc: Neil Conway <[email protected]>; pgsql-hackers

On Wed, Jun 05, 2024 at 01:58:54PM -0400, Tom Lane wrote:
> Nathan Bossart <[email protected]> writes:
>> On Wed, Jun 05, 2024 at 12:22:03PM -0400, Neil Conway wrote:
>>> (2) These functions malloc() a single ntups * sizeof(struct) allocation and
>>> then index into it to fill-in each struct before entering it into the hash
>>> table. It might be more straightforward to just malloc each individual
>>> struct.
> 
>> That'd increase the number of allocations quite significantly, but I'd be
>> surprised if that was noticeable outside of extreme scenarios.  At the
>> moment, I'm inclined to leave these as-is for this reason and because I
>> doubt it'd result in much cleanup, but I'll yield to the majority opinion
>> here.
> 
> I think that would be quite an invasive change; it would require
> many hundreds of edits like
> 
> -		finfo[i].dobj.objType = DO_FUNC;
> +		finfo->dobj.objType = DO_FUNC;
> 
> which aside from being tedious would create a back-patching hazard.
> So I'm kind of -0.1 or so.
> 
> Another angle to this is that Coverity and possibly other tools tend
> to report that these functions leak these allocations, apparently
> because they don't notice that pointers into the allocations get
> stored in hash tables by a subroutine.  I'm not sure if making this
> change would make that worse or better.  If we really want to change
> it, that might be worth checking somehow before we jump.

At the moment, I'm inclined to commit v1 once v18 development opens up.  We
can consider any additional adjustments separately.

-- 
nathan






^ permalink  raw  reply  [nested|flat] 236+ messages in thread

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2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v30 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v57 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v42 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v29 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v31 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v39 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v36 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v33 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v33 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v32 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v44 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v37 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v43 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v41 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v57 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v35 3/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v25 3/8] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v38 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v56 2/6] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v52 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v49 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v40 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v46 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v47 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v45 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v50 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2020-03-13 07:58 [PATCH v51 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]>
2024-06-05 15:13 small pg_dump code cleanup Nathan Bossart <[email protected]>
2024-06-05 16:22 ` Re: small pg_dump code cleanup Neil Conway <[email protected]>
2024-06-05 16:37   ` Re: small pg_dump code cleanup Nathan Bossart <[email protected]>
2024-06-05 17:51     ` Re: small pg_dump code cleanup Neil Conway <[email protected]>
2024-06-05 17:58     ` Re: small pg_dump code cleanup Tom Lane <[email protected]>
2024-06-11 20:30       ` Re: small pg_dump code cleanup Nathan Bossart <[email protected]>

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