pgpool2.git / summary / log / commit / refs
commit 1034e904e87a76f19979d89019acbd2d1a2f067b
Author: Tatsuo Ishii <ishii@postgresql.org>
Date: Sun Mar 18 00:06:36 2012 +0000
Fix hash functions. The pointer to free hash elements did not on
shared memory. Add "volatile" modifier to gloval variables which point
to shared memory area. This is neccessary to prevent the compiler from
changing instruction reordering in the optimization process.
pool_memqcache.c | 65 ++++++++++++++++++++++++++++++++++++--------------------
1 file changed, 42 insertions(+), 23 deletions(-)
diff --git a/pool_memqcache.c b/pool_memqcache.c
index 4776f523d..44716fc0a 100644
--- a/pool_memqcache.c
+++ b/pool_memqcache.c
@@ -111,8 +111,8 @@ static void dump_shmem_cache(POOL_CACHE_BLOCKID blockid);
static int pool_hash_insert(POOL_QUERY_HASH *key, POOL_CACHEID *cacheid, bool update);
static uint32 create_hash_key(POOL_QUERY_HASH *key);
-static POOL_HASH_ELEMENT *get_new_hash_element(void);
-static void put_back_hash_element(POOL_HASH_ELEMENT *element);
+static volatile POOL_HASH_ELEMENT *get_new_hash_element(void);
+static void put_back_hash_element(volatile POOL_HASH_ELEMENT *element);
/*
* Connect to Memcached
@@ -2817,9 +2817,9 @@ long long int pool_stats_count_up_num_cache_hits(void)
* hash_any() is not worth the trouble.
*/
-static POOL_HASH_HEADER *hash_header;
-static POOL_HASH_ELEMENT *hash_elements;
-static POOL_HASH_ELEMENT hash_free_body;
+static volatile POOL_HASH_HEADER *hash_header;
+static volatile POOL_HASH_ELEMENT *hash_elements;
+static volatile POOL_HASH_ELEMENT hash_free_body;
static volatile POOL_HASH_ELEMENT *hash_free;
/*
@@ -2827,6 +2827,8 @@ static volatile POOL_HASH_ELEMENT *hash_free;
* hash keys. The actual number of hash key is rounded up to power of
* 2.
*/
+#undef POOL_HASH_DEBUG
+
int pool_hash_init(int nelements)
{
size_t size;
@@ -2863,6 +2865,10 @@ int pool_hash_init(int nelements)
hash_header->nhash = nelements2;
hash_header->mask = mask;
+#ifdef POOL_HASH_DEBUG
+ pool_log("pool_hash_init: size:%zd nelements2:%d", size, nelements2);
+#endif
+
size = sizeof(POOL_HASH_ELEMENT)*nelements2;
hash_elements = pool_shared_memory_create(size);
if (hash_elements == NULL)
@@ -2871,13 +2877,16 @@ int pool_hash_init(int nelements)
return -1;
}
+#ifdef POOL_HASH_DEBUG
+ pool_log("pool_hash_init: size:%zd nelements2:%d", size, nelements2);
+#endif
+
for (i=0;i<nelements2-1;i++)
{
- hash_elements[i].next = &hash_elements[i+1];
+ hash_elements[i].next = (POOL_HASH_ELEMENT *)&hash_elements[i+1];
}
hash_elements[nelements2-1].next = NULL;
- hash_free = &hash_free_body;
- hash_free->next = hash_elements;
+ hash_free = hash_elements;
return 0;
}
@@ -2935,9 +2944,8 @@ POOL_CACHEID *pool_hash_search(POOL_QUERY_HASH *key)
*/
static int pool_hash_insert(POOL_QUERY_HASH *key, POOL_CACHEID *cacheid, bool update)
{
- volatile POOL_HASH_ELEMENT *element;
- volatile POOL_HASH_ELEMENT *new_element;
- volatile POOL_HASH_ELEMENT **insertion_point;
+ POOL_HASH_ELEMENT *element;
+ POOL_HASH_ELEMENT *new_element;
uint32 hash_key = create_hash_key(key);
@@ -2956,9 +2964,8 @@ static int pool_hash_insert(POOL_QUERY_HASH *key, POOL_CACHEID *cacheid, bool up
}
/*
- * Look for insert location
+ * Look for hash key.
*/
- insertion_point = (volatile POOL_HASH_ELEMENT **)&(hash_header->elements[hash_key].element);
element = hash_header->elements[hash_key].element;
while (element)
@@ -2983,22 +2990,24 @@ static int pool_hash_insert(POOL_QUERY_HASH *key, POOL_CACHEID *cacheid, bool up
return 0;
}
}
- *insertion_point = (volatile POOL_HASH_ELEMENT *)&element->next;
element = element->next;
}
/*
- * Get new element from free list
+ * Ok, same key did not exist. Just insert new hash key.
*/
- new_element = get_new_hash_element();
+ new_element = (POOL_HASH_ELEMENT *)get_new_hash_element();
if (!new_element)
{
pool_error("pool_hash_insert: could not get new element");
return -1;
}
- *insertion_point = new_element;
- new_element->next = NULL;
+ element = hash_header->elements[hash_key].element;
+
+ hash_header->elements[hash_key].element = new_element;
+ new_element->next = element;
+
memcpy((void *)new_element->hashkey.query_hash, key->query_hash, POOL_MD5_HASHKEYLEN);
memcpy((void *)&new_element->cacheid, cacheid, sizeof(POOL_CACHEID));
@@ -3027,7 +3036,7 @@ int pool_hash_delete(POOL_QUERY_HASH *key)
* Look for delete location
*/
found = false;
- delete_point = &(hash_header->elements[hash_key].element);
+ delete_point = (POOL_HASH_ELEMENT **)&(hash_header->elements[hash_key].element);
element = hash_header->elements[hash_key].element;
while (element)
@@ -3081,9 +3090,9 @@ static uint32 create_hash_key(POOL_QUERY_HASH *key)
/*
* Get new free hash element from free list.
*/
-static POOL_HASH_ELEMENT *get_new_hash_element(void)
+static volatile POOL_HASH_ELEMENT *get_new_hash_element(void)
{
- POOL_HASH_ELEMENT *elm;
+ volatile POOL_HASH_ELEMENT *elm;
if (!hash_free->next)
{
@@ -3091,6 +3100,11 @@ static POOL_HASH_ELEMENT *get_new_hash_element(void)
return NULL;
}
+#ifdef POOL_HASH_DEBUG
+ pool_log("get_new_hash_element: hash_free->next:%p hash_free->next->next:%p",
+ hash_free->next, hash_free->next->next);
+#endif
+
elm = hash_free->next;
hash_free->next = elm->next;
@@ -3100,11 +3114,16 @@ static POOL_HASH_ELEMENT *get_new_hash_element(void)
/*
* Put back hash element to free list.
*/
-static void put_back_hash_element(POOL_HASH_ELEMENT *element)
+static void put_back_hash_element(volatile POOL_HASH_ELEMENT *element)
{
POOL_HASH_ELEMENT *elm;
+#ifdef POOL_HASH_DEBUG
+ pool_log("put_back_hash_element: hash_free->next:%p hash_free->next->next:%p",
+ hash_free->next, hash_free->next->next);
+#endif
+
elm = hash_free->next;
- hash_free->next = element;
+ hash_free->next = (POOL_HASH_ELEMENT *)element;
element->next = elm;
}
[parent: 666d71f69c75]