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A pre-requisite patch for the fix for Bug#52044.

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Implement a few simple asserts in my_rwlock_t locks.

include/my_pthread.h:
  Declare two simple assert functions.
include/mysql/psi/mysql_thread.h:
  Add wrappers for new assert functions.
mysys/thr_rwlock.c:
  Add asserts.
sql/sql_base.cc:
  Silence a compiler warning for the case when
  SAFE_MUTEX is not ON.
This commit is contained in:
Konstantin Osipov 2010-08-11 01:12:01 +04:00
commit 265a6edd23
4 changed files with 48 additions and 0 deletions
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18
mysys/thr_rwlock.c
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@ -71,6 +71,9 @@ int my_rw_init(my_rw_lock_t *rwp, my_bool *prefer_readers_attr)
rwp->state = 0;
rwp->waiters = 0;
#ifdef SAFE_MUTEX
rwp->write_thread = 0;
#endif
/* If attribute argument is NULL use default value - prefer writers. */
rwp->prefer_readers= prefer_readers_attr ? *prefer_readers_attr : FALSE;
@ -80,6 +83,7 @@ int my_rw_init(my_rw_lock_t *rwp, my_bool *prefer_readers_attr)
int my_rw_destroy(my_rw_lock_t *rwp)
{
DBUG_ASSERT(rwp->state == 0);
pthread_mutex_destroy( &rwp->lock );
pthread_cond_destroy( &rwp->readers );
pthread_cond_destroy( &rwp->writers );
@ -123,10 +127,15 @@ int my_rw_wrlock(my_rw_lock_t *rwp)
pthread_mutex_lock(&rwp->lock);
rwp->waiters++; /* another writer queued */
my_rw_lock_assert_not_owner(rwp);
while (rwp->state)
pthread_cond_wait(&rwp->writers, &rwp->lock);
rwp->state = -1;
rwp->waiters--;
#ifdef SAFE_MUTEX
rwp->write_thread= pthread_self();
#endif
pthread_mutex_unlock(&rwp->lock);
return(0);
}
@ -142,6 +151,9 @@ int my_rw_trywrlock(my_rw_lock_t *rwp)
{
res=0;
rwp->state = -1;
#ifdef SAFE_MUTEX
rwp->write_thread= pthread_self();
#endif
}
pthread_mutex_unlock(&rwp->lock);
return(res);
@ -154,9 +166,15 @@ int my_rw_unlock(my_rw_lock_t *rwp)
("state: %d waiters: %d", rwp->state, rwp->waiters));
pthread_mutex_lock(&rwp->lock);
DBUG_ASSERT(rwp->state != 0);
if (rwp->state == -1) /* writer releasing */
{
my_rw_lock_assert_write_owner(rwp);
rwp->state= 0; /* mark as available */
#ifdef SAFE_MUTEX
rwp->write_thread= 0;
#endif
if ( rwp->waiters ) /* writers queued */
pthread_cond_signal( &rwp->writers );