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[PATCH 2/5] Add conditional lock feature to dshash 230+ messages / 3 participants [nested] [flat]
* [PATCH 2/5] Add conditional lock feature to dshash @ 2018-09-27 02:15 Kyotaro Horiguchi <[email protected]> 0 siblings, 0 replies; 230+ 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 ----Next_Part(Wed_Jan_22_17_24_04_2020_620)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="0003-Make-archiver-process-an-auxiliary-process.patch" ^ permalink raw reply [nested|flat] 230+ 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; 230+ 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 ----Next_Part(Tue_Dec__3_17_27_59_2019_887)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="v24-0003-Make-archiver-process-an-auxiliary-process.patch" ^ permalink raw reply [nested|flat] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ 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; 230+ 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] 230+ messages in thread
* Re: Add index scan progress to pg_stat_progress_vacuum @ 2022-01-06 20:41 Bossart, Nathan <[email protected]> 0 siblings, 0 replies; 230+ messages in thread From: Bossart, Nathan @ 2022-01-06 20:41 UTC (permalink / raw) To: Imseih (AWS), Sami <[email protected]>; Justin Pryzby <[email protected]>; +Cc: Masahiko Sawada <[email protected]>; Peter Geoghegan <[email protected]>; pgsql-hackers On 12/29/21, 8:44 AM, "Imseih (AWS), Sami" <[email protected]> wrote: > In "pg_stat_progress_vacuum", introduce 2 columns: > > * total_index_vacuum : This is the # of indexes that will be vacuumed. Keep in mind that if failsafe mode kicks in mid-flight to the vacuum, Postgres may choose to forgo index scans. This value will be adjusted accordingly. > * max_index_vacuum_cycle_time : The total elapsed time for a index vacuum cycle is calculated and this value will be updated to reflect the longest vacuum cycle. Until the first cycle completes, this value will be 0. The purpose of this column is to give the user an idea of how long an index vacuum cycle takes to complete. I think that total_index_vacuum is a good thing to have. I would expect this to usually just be the number of indexes on the table, but as you pointed out, this can be different when we are skipping indexes. My only concern with this new column is the potential for confusion when compared with the index_vacuum_count value. index_vacuum_count indicates the number of vacuum cycles completed, but total_index_vacuum indicates the number of indexes that will be vacuumed. However, the names sound like they could refer to the same thing to me. Perhaps we should rename index_vacuum_count to index_vacuum_cycles/index_vacuum_cycle_count, and the new column should be something like num_indexes_to_vacuum or index_vacuum_total. I don't think we need the max_index_vacuum_cycle_time column. While the idea is to give users a rough estimate for how long an index cycle will take, I don't think it will help generate any meaningful estimates for how much longer the vacuum operation will take. IIUC we won't have any idea how many total index vacuum cycles will be needed. Even if we did, the current cycle could take much more or much less time. Also, none of the other progress views seem to provide any timing information, which I suspect is by design to avoid inaccurate estimates. > Introduce a new view called "pg_stat_progress_vacuum_index". This view will track the progress of a worker ( or leader PID ) while it's vacuuming an index. It will expose some key columns: > > * pid: The PID of the worker process > > * leader_pid: The PID of the leader process. This is the column that can be joined with "pg_stat_progress_vacuum". leader_pid and pid can have the same value as a leader can also perform an index vacuum. > > * indrelid: The relid of the index currently being vacuumed > > * vacuum_cycle_ordinal_position: The processing position of the index being vacuumed. This can be useful to determine how many indexes out of the total indexes ( pg_stat_progress_vacuum.total_index_vacuum ) have been vacuumed > > * index_tuples_vacuumed: This is the number of index tuples vacuumed for the index overall. This is useful to show that the vacuum is actually doing work, as the # of tuples keeps increasing. Should we also provide some information for determining the progress of the current cycle? Perhaps there should be an index_tuples_vacuumed_current_cycle column that users can compare with the num_dead_tuples value in pg_stat_progress_vacuum. However, perhaps the number of tuples vacuumed in the current cycle can already be discovered via index_tuples_vacuumed % max_dead_tuples. +void +rusage_adjust(const PGRUsage *ru0, PGRUsage *ru1) +{ + if (ru1->tv.tv_usec < ru0->tv.tv_usec) + { + ru1->tv.tv_sec--; + ru1->tv.tv_usec += 1000000; + } + if (ru1->ru.ru_stime.tv_usec < ru0->ru.ru_stime.tv_usec) + { + ru1->ru.ru_stime.tv_sec--; + ru1->ru.ru_stime.tv_usec += 1000000; + } + if (ru1->ru.ru_utime.tv_usec < ru0->ru.ru_utime.tv_usec) + { + ru1->ru.ru_utime.tv_sec--; + ru1->ru.ru_utime.tv_usec += 1000000; + } +} I think this function could benefit from a comment. Without going through it line by line, it is not clear to me exactly what it is doing. I know we're still working on what exactly this stuff should look like, but I would suggest adding the documentation changes in the near future. Nathan ^ permalink raw reply [nested|flat] 230+ messages in thread
end of thread, other threads:[~2022-01-06 20:41 UTC | newest] Thread overview: 230+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2018-09-27 02:15 [PATCH 2/5] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]> 2018-09-27 02:15 [PATCH v24 2/5] 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 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 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 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 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 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 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 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 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 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 v48 2/7] Add conditional lock feature to dshash Kyotaro Horiguchi <[email protected]> 2020-03-13 07:58 [PATCH v34 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 v52 2/7] 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 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 v48 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 v41 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 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 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 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 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 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 v46 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 v56 2/6] 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 v46 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 v35 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 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 v48 2/7] Add 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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 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 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 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 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 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 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 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 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 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 v52 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 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 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 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 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 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 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 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 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 v56 2/6] 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 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 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 v36 3/7] 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 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 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 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 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 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 v30 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 v57 2/6] 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 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 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 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 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 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 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 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 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 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 v43 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 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 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 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 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 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 v39 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 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 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 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 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 v32 3/7] 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 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 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 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 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 v37 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 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 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 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 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 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 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 v40 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 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 v25 3/8] 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]> 2022-01-06 20:41 Re: Add index scan progress to pg_stat_progress_vacuum Bossart, Nathan <[email protected]>
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