void thr_lock_data_init(THR_LOCK *lock,THR_LOCK_DATA *data, void *param)
{
data->lock=lock;
data->type=TL_UNLOCK;
data->thread=pthread_self();
data->thread_id=my_thread_id(); /* for debugging */
data->status_param=param;
data->cond=0;
}
void thread_unlock_mutex(mutex_t *mtx)
{
uint8_t ptid;
thread_t *prev;
if (!mtx) {
return;
}
if (unlock_mutex(my_thread_id(), mtx)) {
ptid = mtx->locker_tid;
prev = get_thread(ptid);
if (prev) {
scheduler_resume_thread(THREAD_FLAG_WAIT_MUTEX, ptid);
}
}
}
void thr_lock_info_init(THR_LOCK_INFO *info)
{
info->thread= pthread_self();
info->thread_id= my_thread_id(); /* for debugging */
info->n_cursors= 0;
}
int thr_lock(THR_LOCK_DATA *data,enum thr_lock_type lock_type)
{
THR_LOCK *lock=data->lock;
int result=0;
DBUG_ENTER("thr_lock");
data->next=0;
data->cond=0; /* safety */
data->type=lock_type;
data->thread=pthread_self(); /* Must be reset ! */
data->thread_id=my_thread_id(); /* Must be reset ! */
VOID(pthread_mutex_lock(&lock->mutex));
DBUG_PRINT("lock",("data: %lx thread: %ld lock: %lx type: %d",
data,data->thread_id,lock,(int) lock_type));
check_locks(lock,(uint) lock_type <= (uint) TL_READ_NO_INSERT ?
"enter read_lock" : "enter write_lock",0);
if ((int) lock_type <= (int) TL_READ_NO_INSERT)
{
/* Request for READ lock */
if (lock->write.data)
{
/* We can allow a read lock even if there is already a write lock
on the table in one the following cases:
- This thread alread have a write lock on the table
- The write lock is TL_WRITE_ALLOW_READ or TL_WRITE_DELAYED
and the read lock is TL_READ_HIGH_PRIORITY or TL_READ
- The write lock is TL_WRITE_CONCURRENT_INSERT or TL_WRITE_ALLOW_WRITE
and the read lock is not TL_READ_NO_INSERT
*/
DBUG_PRINT("lock",("write locked by thread: %ld",
lock->write.data->thread_id));
if (pthread_equal(data->thread,lock->write.data->thread) ||
(lock->write.data->type <= TL_WRITE_DELAYED &&
(((int) lock_type <= (int) TL_READ_HIGH_PRIORITY) ||
(lock->write.data->type != TL_WRITE_CONCURRENT_INSERT &&
lock->write.data->type != TL_WRITE_ALLOW_READ))))
{ /* Already got a write lock */
(*lock->read.last)=data; /* Add to running FIFO */
data->prev=lock->read.last;
lock->read.last= &data->next;
if ((int) lock_type == (int) TL_READ_NO_INSERT)
lock->read_no_write_count++;
check_locks(lock,"read lock with old write lock",0);
if (lock->get_status)
(*lock->get_status)(data->status_param);
statistic_increment(locks_immediate,&THR_LOCK_lock);
goto end;
}
if (lock->write.data->type == TL_WRITE_ONLY)
{
/* We are not allowed to get a READ lock in this case */
data->type=TL_UNLOCK;
result=1; /* Can't wait for this one */
goto end;
}
}
else if (!lock->write_wait.data ||
lock->write_wait.data->type <= TL_WRITE_LOW_PRIORITY ||
lock_type == TL_READ_HIGH_PRIORITY ||
have_old_read_lock(lock->read.data,data->thread))
{ /* No important write-locks */
(*lock->read.last)=data; /* Add to running FIFO */
data->prev=lock->read.last;
lock->read.last= &data->next;
if (lock->get_status)
(*lock->get_status)(data->status_param);
if ((int) lock_type == (int) TL_READ_NO_INSERT)
lock->read_no_write_count++;
check_locks(lock,"read lock with no write locks",0);
statistic_increment(locks_immediate,&THR_LOCK_lock);
goto end;
}
/* Can't get lock yet; Wait for it */
DBUG_RETURN(wait_for_lock(&lock->read_wait,data,0));
}
else /* Request for WRITE lock */
{
if (lock_type == TL_WRITE_DELAYED)
{
if (lock->write.data && lock->write.data->type == TL_WRITE_ONLY)
{
data->type=TL_UNLOCK;
result=1; /* Can't wait for this one */
goto end;
}
/*
if there is a TL_WRITE_ALLOW_READ lock, we have to wait for a lock
(TL_WRITE_ALLOW_READ is used for ALTER TABLE in MySQL)
*/
if ((!lock->write.data ||
lock->write.data->type != TL_WRITE_ALLOW_READ) &&
!have_specific_lock(lock->write_wait.data,TL_WRITE_ALLOW_READ) &&
(lock->write.data || lock->read.data))
{
/* Add delayed write lock to write_wait queue, and return at once */
(*lock->write_wait.last)=data;
data->prev=lock->write_wait.last;
lock->write_wait.last= &data->next;
data->cond=get_cond();
if (lock->get_status)
(*lock->get_status)(data->status_param);
statistic_increment(locks_immediate,&THR_LOCK_lock);
goto end;
}
}
else if (lock_type == TL_WRITE_CONCURRENT_INSERT && ! lock->check_status)
data->type=lock_type= thr_upgraded_concurrent_insert_lock;
if (lock->write.data) /* If there is a write lock */
{
if (lock->write.data->type == TL_WRITE_ONLY)
{
/* We are not allowed to get a lock in this case */
data->type=TL_UNLOCK;
result=1; /* Can't wait for this one */
goto end;
}
/*
The following test will not work if the old lock was a
TL_WRITE_ALLOW_WRITE, TL_WRITE_ALLOW_READ or TL_WRITE_DELAYED in
the same thread, but this will never happen within MySQL.
*/
if (pthread_equal(data->thread,lock->write.data->thread) ||
(lock_type == TL_WRITE_ALLOW_WRITE &&
!lock->write_wait.data &&
lock->write.data->type == TL_WRITE_ALLOW_WRITE))
{
/* We have already got a write lock or all locks are
TL_WRITE_ALLOW_WRITE */
(*lock->write.last)=data; /* Add to running fifo */
data->prev=lock->write.last;
lock->write.last= &data->next;
check_locks(lock,"second write lock",0);
if (data->lock->get_status)
(*data->lock->get_status)(data->status_param);
statistic_increment(locks_immediate,&THR_LOCK_lock);
goto end;
}
DBUG_PRINT("lock",("write locked by thread: %ld",
lock->write.data->thread_id));
}
else
{
if (!lock->write_wait.data)
{ /* no scheduled write locks */
if (lock_type == TL_WRITE_CONCURRENT_INSERT &&
(*lock->check_status)(data->status_param))
data->type=lock_type= thr_upgraded_concurrent_insert_lock;
if (!lock->read.data ||
(lock_type <= TL_WRITE_DELAYED &&
((lock_type != TL_WRITE_CONCURRENT_INSERT &&
lock_type != TL_WRITE_ALLOW_WRITE) ||
!lock->read_no_write_count)))
{
(*lock->write.last)=data; /* Add as current write lock */
data->prev=lock->write.last;
lock->write.last= &data->next;
if (data->lock->get_status)
(*data->lock->get_status)(data->status_param);
check_locks(lock,"only write lock",0);
statistic_increment(locks_immediate,&THR_LOCK_lock);
goto end;
}
}
DBUG_PRINT("lock",("write locked by thread: %ld, type: %ld",
lock->read.data->thread_id,data->type));
}
DBUG_RETURN(wait_for_lock(&lock->write_wait,data,0));
}
end:
pthread_mutex_unlock(&lock->mutex);
DBUG_RETURN(result);
}