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semaphores replaced by rwlock

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This commit is contained in:
bell@sanja.is.com.ua
2002-06-30 12:08:58 +03:00
parent e5b02fbe6e
commit 2426972c5b
4 changed files with 31 additions and 45 deletions
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63
sql/sql_cache.cc
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@ -299,11 +299,15 @@ TODO list:
pthread_mutex_lock(M);}
#define MUTEX_UNLOCK(M) {DBUG_PRINT("lock", ("mutex unlock 0x%lx",\
(ulong)(M))); pthread_mutex_unlock(M);}
#define SEM_LOCK(M) { int val = 0; sem_getvalue (M, &val); \
DBUG_PRINT("lock", ("sem lock 0x%lx (%d)", (ulong)(M), val)); \
sem_wait(M); DBUG_PRINT("lock", ("sem lock ok")); }
#define SEM_UNLOCK(M) {DBUG_PRINT("info", ("sem unlock 0x%lx", (ulong)(M))); \
sem_post(M); DBUG_PRINT("info", ("sem unlock ok")); }
#define RW_WLOCK(M) {DBUG_PRINT("lock", ("rwlock wlock 0x%lx",(ulong)(M))); \
if (!rw_wrlock(M)) DBUG_PRINT("lock", ("rwlock wlock ok")) \
else DBUG_PRINT("lock", ("rwlock wlock FAILED %d", errno)); }
#define RW_RLOCK(M) {DBUG_PRINT("lock", ("rwlock rlock 0x%lx", (ulong)(M))); \
if (!rw_rdlock(M)) DBUG_PRINT("lock", ("rwlock rlock ok")) \
else DBUG_PRINT("lock", ("rwlock wlock FAILED %d", errno)); }
#define RW_UNLOCK(M) {DBUG_PRINT("lock", ("rwlock wlock 0x%lx",(ulong)(M))); \
if (!rw_unlock(M)) DBUG_PRINT("lock", ("rwlock unlock ok")) \
else DBUG_PRINT("lock", ("rwlock unlock FAILED %d", errno)); }
#define STRUCT_LOCK(M) {DBUG_PRINT("lock", ("%d struct lock...",__LINE__)); \
pthread_mutex_lock(M);DBUG_PRINT("lock", ("struct lock OK"));}
#define STRUCT_UNLOCK(M) { \
@ -326,8 +330,9 @@ TODO list:
#else
#define MUTEX_LOCK(M) pthread_mutex_lock(M)
#define MUTEX_UNLOCK(M) pthread_mutex_unlock(M)
#define SEM_LOCK(M) sem_wait(M)
#define SEM_UNLOCK(M) sem_post(M)
#define RW_WLOCK(M) rw_wrlock(M)
#define RW_RLOCK(M) rw_rdlock(M)
#define RW_UNLOCK(M) rw_unlock(M)
#define STRUCT_LOCK(M) pthread_mutex_lock(M)
#define STRUCT_UNLOCK(M) pthread_mutex_unlock(M)
#define BLOCK_LOCK_WR(B) B->query()->lock_writing()
@ -445,9 +450,7 @@ void Query_cache_query::init_n_lock()
{
DBUG_ENTER("Query_cache_query::init_n_lock");
res=0; wri = 0; len = 0;
sem_init(&lock, 0, 1);
pthread_mutex_init(&clients_guard,MY_MUTEX_INIT_FAST);
clients = 0;
my_rwlock_init(&lock, NULL);
lock_writing();
DBUG_PRINT("qcache", ("inited & locked query for block 0x%lx",
((byte*) this)-ALIGN_SIZE(sizeof(Query_cache_block))));
@ -465,8 +468,7 @@ void Query_cache_query::unlock_n_destroy()
active semaphore
*/
this->unlock_writing();
sem_destroy(&lock);
pthread_mutex_destroy(&clients_guard);
rwlock_destroy(&lock);
DBUG_VOID_RETURN;
}
@ -479,9 +481,9 @@ void Query_cache_query::unlock_n_destroy()
Lock for read prevents only locking for write.
*/
void Query_cache_query::lock_writing()
inline void Query_cache_query::lock_writing()
{
SEM_LOCK(&lock);
RW_WLOCK(&lock);
}
@ -495,41 +497,31 @@ void Query_cache_query::lock_writing()
my_bool Query_cache_query::try_lock_writing()
{
DBUG_ENTER("Query_cache_block::try_lock_writing");
if (sem_trywait(&lock)!=0 || clients != 0)
if (rw_trywrlock(&lock)!=0)
{
DBUG_PRINT("info", ("can't lock semaphore"));
DBUG_PRINT("info", ("can't lock rwlock"));
DBUG_RETURN(0);
}
DBUG_PRINT("info", ("mutex 'lock' 0x%lx locked", (ulong) &lock));
DBUG_PRINT("info", ("rwlock 0x%lx locked", (ulong) &lock));
DBUG_RETURN(1);
}
void Query_cache_query::lock_reading()
inline void Query_cache_query::lock_reading()
{
MUTEX_LOCK(&clients_guard);
if (++clients == 1)
SEM_LOCK(&lock);
MUTEX_UNLOCK(&clients_guard);
RW_RLOCK(&lock);
}
void Query_cache_query::unlock_writing()
inline void Query_cache_query::unlock_writing()
{
SEM_UNLOCK(&lock);
RW_UNLOCK(&lock);
}
void Query_cache_query::unlock_reading()
inline void Query_cache_query::unlock_reading()
{
/*
To avoid unlocking semaphore before unlocking mutex (that may cause
destroying locked mutex), we use temporary boolean variable 'unlock'.
*/
MUTEX_LOCK(&clients_guard);
bool ulock = ((--clients) == 0);
MUTEX_UNLOCK(&clients_guard);
if (ulock) SEM_UNLOCK(&lock);
RW_UNLOCK(&lock);
}
extern "C"
@ -2339,7 +2331,7 @@ Query_cache::double_linked_list_simple_include(Query_cache_block *point,
*list_pointer=point->next=point->prev=point;
else
{
// insert to and of list
// insert to the end of list
point->next = (*list_pointer);
point->prev = (*list_pointer)->prev;
point->prev->next = point;
@ -2634,8 +2626,7 @@ my_bool Query_cache::move_by_type(byte **border,
} while ( result_block != first_result_block );
}
Query_cache_query *new_query= ((Query_cache_query *) new_block->data());
sem_init(&new_query->lock, 0, 1);
pthread_mutex_init(&new_query->clients_guard,MY_MUTEX_INIT_FAST);
my_rwlock_init(&new_query->lock, NULL);
/*
If someone is writing to this block, inform the writer that the block