my_bool thr_reschedule_write_lock(THR_LOCK_DATA *data)
{
THR_LOCK *lock=data->lock;
DBUG_ENTER("thr_reschedule_write_lock");
pthread_mutex_lock(&lock->mutex);
if (!lock->read_wait.data) /* No waiting read locks */
{
pthread_mutex_unlock(&lock->mutex);
DBUG_RETURN(0);
}
data->type=TL_WRITE_DELAYED;
if (lock->update_status)
(*lock->update_status)(data->status_param);
if (((*data->prev)=data->next)) /* remove from lock-list */
data->next->prev= data->prev;
else
lock->write.last=data->prev;
if ((data->next=lock->write_wait.data)) /* Put first in lock_list */
data->next->prev= &data->next;
else
lock->write_wait.last= &data->next;
data->prev= &lock->write_wait.data;
data->cond=get_cond(); /* This was zero */
lock->write_wait.data=data;
free_all_read_locks(lock,0);
pthread_mutex_unlock(&lock->mutex);
DBUG_RETURN(thr_upgrade_write_delay_lock(data));
}
static void wake_up_waiters(THR_LOCK *lock)
{
THR_LOCK_DATA *data;
enum thr_lock_type lock_type;
DBUG_ENTER("wake_up_waiters");
if (!lock->write.data) /* If no active write locks */
{
data=lock->write_wait.data;
if (!lock->read.data) /* If no more locks in use */
{
/* Release write-locks with TL_WRITE or TL_WRITE_ONLY priority first */
if (data &&
(data->type != TL_WRITE_LOW_PRIORITY || !lock->read_wait.data ||
lock->read_wait.data->type < TL_READ_HIGH_PRIORITY))
{
if (lock->write_lock_count++ > max_write_lock_count)
{
/* Too many write locks in a row; Release all waiting read locks */
lock->write_lock_count=0;
if (lock->read_wait.data)
{
DBUG_PRINT("info",("Freeing all read_locks because of max_write_lock_count"));
free_all_read_locks(lock,0);
goto end;
}
}
for (;;)
{
if (((*data->prev)=data->next)) /* remove from wait-list */
data->next->prev= data->prev;
else
lock->write_wait.last=data->prev;
(*lock->write.last)=data; /* Put in execute list */
data->prev=lock->write.last;
data->next=0;
lock->write.last= &data->next;
if (data->type == TL_WRITE_CONCURRENT_INSERT &&
(*lock->check_status)(data->status_param))
data->type=TL_WRITE; /* Upgrade lock */
DBUG_PRINT("lock",("giving write lock of type %d to thread: %ld",
data->type, data->owner->info->thread_id));
{
pthread_cond_t *cond=data->cond;
data->cond=0; /* Mark thread free */
VOID(pthread_cond_signal(cond)); /* Start waiting thread */
}
if (data->type != TL_WRITE_ALLOW_WRITE ||
!lock->write_wait.data ||
lock->write_wait.data->type != TL_WRITE_ALLOW_WRITE)
break;
data=lock->write_wait.data; /* Free this too */
}
if (data->type >= TL_WRITE_LOW_PRIORITY)
goto end;
/* Release possible read locks together with the write lock */
}
if (lock->read_wait.data)
free_all_read_locks(lock,
data &&
(data->type == TL_WRITE_CONCURRENT_INSERT ||
data->type == TL_WRITE_ALLOW_WRITE));
else
{
DBUG_PRINT("lock",("No waiting read locks to free"));
}
}
else if (data &&
(lock_type=data->type) <= TL_WRITE_DELAYED &&
((lock_type != TL_WRITE_CONCURRENT_INSERT &&
lock_type != TL_WRITE_ALLOW_WRITE) ||
!lock->read_no_write_count))
{
/*
For DELAYED, ALLOW_READ, WRITE_ALLOW_WRITE or CONCURRENT_INSERT locks
start WRITE locks together with the READ locks
*/
if (lock_type == TL_WRITE_CONCURRENT_INSERT &&
(*lock->check_status)(data->status_param))
{
data->type=TL_WRITE; /* Upgrade lock */
if (lock->read_wait.data)
free_all_read_locks(lock,0);
goto end;
}
do {
pthread_cond_t *cond=data->cond;
if (((*data->prev)=data->next)) /* remove from wait-list */
data->next->prev= data->prev;
else
lock->write_wait.last=data->prev;
(*lock->write.last)=data; /* Put in execute list */
data->prev=lock->write.last;
lock->write.last= &data->next;
data->next=0; /* Only one write lock */
data->cond=0; /* Mark thread free */
VOID(pthread_cond_signal(cond)); /* Start waiting thread */
} while (lock_type == TL_WRITE_ALLOW_WRITE &&
(data=lock->write_wait.data) &&
data->type == TL_WRITE_ALLOW_WRITE);
if (lock->read_wait.data)
free_all_read_locks(lock,
(lock_type == TL_WRITE_CONCURRENT_INSERT ||
lock_type == TL_WRITE_ALLOW_WRITE));
}
else if (!data && lock->read_wait.data)
free_all_read_locks(lock,0);
}
end:
check_locks(lock, "after waking up waiters", 0);
DBUG_VOID_RETURN;
}
void thr_unlock(THR_LOCK_DATA *data)
{
THR_LOCK *lock=data->lock;
enum thr_lock_type lock_type=data->type;
DBUG_ENTER("thr_unlock");
DBUG_PRINT("lock",("data: %lx thread: %ld lock: %lx",
data,data->thread_id,lock));
pthread_mutex_lock(&lock->mutex);
check_locks(lock,"start of release lock",0);
if (((*data->prev)=data->next)) /* remove from lock-list */
data->next->prev= data->prev;
else if (lock_type <= TL_READ_NO_INSERT)
lock->read.last=data->prev;
else if (lock_type == TL_WRITE_DELAYED && data->cond)
{
/* This only happens in extreme circumstances when a
write delayed lock that is waiting for a lock */
lock->write_wait.last=data->prev; /* Put it on wait queue */
}
else
lock->write.last=data->prev;
if (lock_type >= TL_WRITE_CONCURRENT_INSERT && lock->update_status)
(*lock->update_status)(data->status_param);
if (lock_type == TL_READ_NO_INSERT)
lock->read_no_write_count--;
data->type=TL_UNLOCK; /* Mark unlocked */
check_locks(lock,"after releasing lock",1);
if (!lock->write.data) /* If no active write locks */
{
data=lock->write_wait.data;
if (!lock->read.data) /* If no more locks in use */
{
/* Release write-locks with TL_WRITE or TL_WRITE_ONLY priority first */
if (data &&
(data->type != TL_WRITE_LOW_PRIORITY || !lock->read_wait.data ||
lock->read_wait.data->type < TL_READ_HIGH_PRIORITY))
{
if (lock->write_lock_count++ > max_write_lock_count)
{
/* Too many write locks in a row; Release all waiting read locks */
lock->write_lock_count=0;
if (lock->read_wait.data)
{
DBUG_PRINT("info",("Freeing all read_locks because of max_write_lock_count"));
free_all_read_locks(lock,0);
goto end;
}
}
for (;;)
{
if (((*data->prev)=data->next)) /* remove from wait-list */
data->next->prev= data->prev;
else
lock->write_wait.last=data->prev;
(*lock->write.last)=data; /* Put in execute list */
data->prev=lock->write.last;
data->next=0;
lock->write.last= &data->next;
if (data->type == TL_WRITE_CONCURRENT_INSERT &&
(*lock->check_status)(data->status_param))
data->type=TL_WRITE; /* Upgrade lock */
DBUG_PRINT("lock",("giving write lock of type %d to thread: %ld",
data->type,data->thread_id));
{
pthread_cond_t *cond=data->cond;
data->cond=0; /* Mark thread free */
VOID(pthread_cond_signal(cond)); /* Start waiting thread */
}
if (data->type != TL_WRITE_ALLOW_WRITE ||
!lock->write_wait.data ||
lock->write_wait.data->type != TL_WRITE_ALLOW_WRITE)
break;
data=lock->write_wait.data; /* Free this too */
}
if (data->type >= TL_WRITE_LOW_PRIORITY)
{
check_locks(lock,"giving write lock",0);
pthread_mutex_unlock(&lock->mutex);
DBUG_VOID_RETURN;
}
/* Release possible read locks together with the write lock */
}
if (lock->read_wait.data)
free_all_read_locks(lock,
data &&
(data->type == TL_WRITE_CONCURRENT_INSERT ||
data->type == TL_WRITE_ALLOW_WRITE));
else
{
DBUG_PRINT("lock",("No waiting read locks to free"));
}
}
else if (data &&
(lock_type=data->type) <= TL_WRITE_DELAYED &&
((lock_type != TL_WRITE_CONCURRENT_INSERT &&
lock_type != TL_WRITE_ALLOW_WRITE) ||
!lock->read_no_write_count))
{
/*
For DELAYED, ALLOW_READ, WRITE_ALLOW_WRITE or CONCURRENT_INSERT locks
start WRITE locks together with the READ locks
*/
if (lock_type == TL_WRITE_CONCURRENT_INSERT &&
(*lock->check_status)(data->status_param))
{
data->type=TL_WRITE; /* Upgrade lock */
if (lock->read_wait.data)
free_all_read_locks(lock,0);
goto end;
}
do {
pthread_cond_t *cond=data->cond;
if (((*data->prev)=data->next)) /* remove from wait-list */
data->next->prev= data->prev;
else
lock->write_wait.last=data->prev;
(*lock->write.last)=data; /* Put in execute list */
data->prev=lock->write.last;
lock->write.last= &data->next;
data->next=0; /* Only one write lock */
data->cond=0; /* Mark thread free */
VOID(pthread_cond_signal(cond)); /* Start waiting thread */
} while (lock_type == TL_WRITE_ALLOW_WRITE &&
(data=lock->write_wait.data) &&
data->type == TL_WRITE_ALLOW_WRITE);
if (lock->read_wait.data)
free_all_read_locks(lock,
(lock_type == TL_WRITE_CONCURRENT_INSERT ||
lock_type == TL_WRITE_ALLOW_WRITE));
}
else if (!data && lock->read_wait.data)
free_all_read_locks(lock,0);
}
end:
check_locks(lock,"thr_unlock",0);
pthread_mutex_unlock(&lock->mutex);
DBUG_VOID_RETURN;
}
