path: root/storage/xtradb/include/sync0rw.ic

/*****************************************************************************

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Copyright (c) 2008, Google Inc.

Portions of this file contain modifications contributed and copyrighted by
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this program; if not, write to the Free Software Foundation, Inc.,
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*****************************************************************************/

/**************************************************//**
@file include/sync0rw.ic
The read-write lock (for threads)

Created 9/11/1995 Heikki Tuuri
*******************************************************/

/******************************************************************//**
Lock a regular or priority rw-lock in shared mode for the current thread. If
the rw-lock is locked in exclusive mode, or there is an exclusive lock request
waiting, the function spins a preset time (controlled by SYNC_SPIN_ROUNDS),
waiting for the lock before suspending the thread. */
UNIV_INTERN
void
rw_lock_s_lock_spin(
/*================*/
	void*		_lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the lock will
				be passed to another thread to unlock */
	bool		priority_lock,
				/*!< in: whether the lock is a priority lock */
	bool		high_priority,
				/*!< in: whether we are acquiring a priority
				lock with high priority */
	const char*	file_name,/*!< in: file name where lock requested */
	ulint		line);	/*!< in: line where requested */
#ifdef UNIV_SYNC_DEBUG
/******************************************************************//**
Inserts the debug information for an rw-lock. */
UNIV_INTERN
void
rw_lock_add_debug_info(
/*===================*/
	rw_lock_t*	lock,		/*!< in: rw-lock */
	ulint		pass,		/*!< in: pass value */
	ulint		lock_type,	/*!< in: lock type */
	const char*	file_name,	/*!< in: file where requested */
	ulint		line);		/*!< in: line where requested */
/******************************************************************//**
Removes a debug information struct for an rw-lock. */
UNIV_INTERN
void
rw_lock_remove_debug_info(
/*======================*/
	rw_lock_t*	lock,		/*!< in: rw-lock */
	ulint		pass,		/*!< in: pass value */
	ulint		lock_type);	/*!< in: lock type */
#endif /* UNIV_SYNC_DEBUG */

/********************************************************************//**
Check if there are threads waiting for the rw-lock.
@return	1 if waiters, 0 otherwise */
UNIV_INLINE
ulint
rw_lock_get_waiters(
/*================*/
	const rw_lock_t*	lock)	/*!< in: rw-lock */
{
	return(lock->waiters);
}

/********************************************************************//**
Check if there are threads waiting for the priority rw-lock.
@return	1 if waiters, 0 otherwise */
UNIV_INLINE
ulint
rw_lock_get_waiters(
/*================*/
	const prio_rw_lock_t*	lock)	/*!< in: rw-lock */
{
	return rw_lock_get_waiters(&lock->base_lock)
		|| lock->high_priority_s_waiters
		|| lock->high_priority_x_waiters;
}

/********************************************************************//**
Sets lock->waiters to 1. It is not an error if lock->waiters is already
1. On platforms where ATOMIC builtins are used this function enforces a
memory barrier. */
UNIV_INLINE
void
rw_lock_set_waiter_flag(
/*====================*/
	rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
#ifdef INNODB_RW_LOCKS_USE_ATOMICS
	(void) os_compare_and_swap_ulint(&lock->waiters, 0, 1);
#else /* INNODB_RW_LOCKS_USE_ATOMICS */
	lock->waiters = 1;
	os_wmb;
#endif /* INNODB_RW_LOCKS_USE_ATOMICS */
}

/********************************************************************//**
Resets lock->waiters to 0. It is not an error if lock->waiters is already
0. On platforms where ATOMIC builtins are used this function enforces a
memory barrier. */
UNIV_INLINE
void
rw_lock_reset_waiter_flag(
/*======================*/
	rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
#ifdef INNODB_RW_LOCKS_USE_ATOMICS
	(void) os_compare_and_swap_ulint(&lock->waiters, 1, 0);
#else /* INNODB_RW_LOCKS_USE_ATOMICS */
	lock->waiters = 0;
	os_wmb;
#endif /* INNODB_RW_LOCKS_USE_ATOMICS */
}

/******************************************************************//**
Returns the write-status of the lock - this function made more sense
with the old rw_lock implementation.
@return	RW_LOCK_NOT_LOCKED, RW_LOCK_EX, RW_LOCK_WAIT_EX */
UNIV_INLINE
ulint
rw_lock_get_writer(
/*===============*/
	const rw_lock_t*	lock)	/*!< in: rw-lock */
{
	lint lock_word = lock->lock_word;
	if (lock_word > 0) {
		/* return NOT_LOCKED in s-lock state, like the writer
		member of the old lock implementation. */
		return(RW_LOCK_NOT_LOCKED);
	} else if ((lock_word == 0) || (lock_word <= -X_LOCK_DECR)) {
		return(RW_LOCK_EX);
	} else {
		ut_ad(lock_word > -X_LOCK_DECR);
		return(RW_LOCK_WAIT_EX);
	}
}

/******************************************************************//**
Returns the write-status of the priority lock - this function made more sense
with the old rw_lock implementation.
@return	RW_LOCK_NOT_LOCKED, RW_LOCK_EX, RW_LOCK_WAIT_EX */
UNIV_INLINE
ulint
rw_lock_get_writer(
/*===============*/
	const prio_rw_lock_t*	lock)	/*!< in: rw-lock */
{
	return(rw_lock_get_writer(&lock->base_lock));
}

/******************************************************************//**
Returns the number of readers.
@return	number of readers */
UNIV_INLINE
ulint
rw_lock_get_reader_count(
/*=====================*/
	const rw_lock_t*	lock)	/*!< in: rw-lock */
{
	lint lock_word = lock->lock_word;
	if (lock_word > 0) {
		/* s-locked, no x-waiters */
		return(X_LOCK_DECR - lock_word);
	} else if (lock_word < 0 && lock_word > -X_LOCK_DECR) {
		/* s-locked, with x-waiters */
		return((ulint)(-lock_word));
	}
	return(0);
}

/******************************************************************//**
Returns the number of readers.
@return	number of readers */
UNIV_INLINE
ulint
rw_lock_get_reader_count(
/*=====================*/
	const prio_rw_lock_t*	lock)	/*!< in: rw-lock */
{
	return(rw_lock_get_reader_count(&lock->base_lock));
}

#ifndef INNODB_RW_LOCKS_USE_ATOMICS
UNIV_INLINE
ib_mutex_t*
rw_lock_get_mutex(
/*==============*/
	rw_lock_t*	lock)
{
	return(&(lock->mutex));
}
#endif

/******************************************************************//**
Returns the value of writer_count for the lock. Does not reserve the lock
mutex, so the caller must be sure it is not changed during the call.
@return	value of writer_count */
UNIV_INLINE
ulint
rw_lock_get_x_lock_count(
/*=====================*/
	const rw_lock_t*	lock)	/*!< in: rw-lock */
{
	lint lock_copy = lock->lock_word;
	if ((lock_copy != 0) && (lock_copy > -X_LOCK_DECR)) {
		return(0);
	}
	return((lock_copy == 0) ? 1 : (2 - (lock_copy + X_LOCK_DECR)));
}

/******************************************************************//**
Returns the value of writer_count for the priority lock. Does not reserve the
lock mutex, so the caller must be sure it is not changed during the call.
@return	value of writer_count */
UNIV_INLINE
ulint
rw_lock_get_x_lock_count(
/*=====================*/
	const prio_rw_lock_t*	lock)	/*!< in: rw-lock */
{
	return(rw_lock_get_x_lock_count(&lock->base_lock));
}

/******************************************************************//**
Two different implementations for decrementing the lock_word of a rw_lock:
one for systems supporting atomic operations, one for others. This does
does not support recusive x-locks: they should be handled by the caller and
need not be atomic since they are performed by the current lock holder.
Returns true if the decrement was made, false if not.
@return	TRUE if decr occurs */
UNIV_INLINE
ibool
rw_lock_lock_word_decr(
/*===================*/
	rw_lock_t*	lock,		/*!< in/out: rw-lock */
	ulint		amount)		/*!< in: amount to decrement */
{
#ifdef INNODB_RW_LOCKS_USE_ATOMICS
	lint local_lock_word;

	os_rmb;
	local_lock_word = lock->lock_word;
	while (local_lock_word > 0) {
		if (os_compare_and_swap_lint(&lock->lock_word,
					     local_lock_word,
					     local_lock_word - amount)) {
			return(TRUE);
		}
		local_lock_word = lock->lock_word;
	}
	return(FALSE);
#else /* INNODB_RW_LOCKS_USE_ATOMICS */
	ibool success = FALSE;
	mutex_enter(&(lock->mutex));
	if (lock->lock_word > 0) {
		lock->lock_word -= amount;
		success = TRUE;
	}
	mutex_exit(&(lock->mutex));
	return(success);
#endif /* INNODB_RW_LOCKS_USE_ATOMICS */
}

/******************************************************************//**
Increments lock_word the specified amount and returns new value.
@return	lock->lock_word after increment */
UNIV_INLINE
lint
rw_lock_lock_word_incr(
/*===================*/
	rw_lock_t*	lock,		/*!< in/out: rw-lock */
	ulint		amount)		/*!< in: amount of increment */
{
#ifdef INNODB_RW_LOCKS_USE_ATOMICS
	return(os_atomic_increment_lint(&lock->lock_word, amount));
#else /* INNODB_RW_LOCKS_USE_ATOMICS */
	lint local_lock_word;

	mutex_enter(&(lock->mutex));

	lock->lock_word += amount;
	local_lock_word = lock->lock_word;

	mutex_exit(&(lock->mutex));

	return(local_lock_word);
#endif /* INNODB_RW_LOCKS_USE_ATOMICS */
}

/******************************************************************//**
This function sets the lock->writer_thread and lock->recursive fields.
For platforms where we are using atomic builtins instead of lock->mutex
it sets the lock->writer_thread field using atomics to ensure memory
ordering. Note that it is assumed that the caller of this function
effectively owns the lock i.e.: nobody else is allowed to modify
lock->writer_thread at this point in time.
The protocol is that lock->writer_thread MUST be updated BEFORE the
lock->recursive flag is set. */
UNIV_INLINE
void
rw_lock_set_writer_id_and_recursion_flag(
/*=====================================*/
	rw_lock_t*	lock,		/*!< in/out: lock to work on */
	ibool		recursive)	/*!< in: TRUE if recursion
					allowed */
{
	os_thread_id_t	curr_thread	= os_thread_get_curr_id();

#ifdef INNODB_RW_LOCKS_USE_ATOMICS
	os_thread_id_t	local_thread;
	ibool		success;

	/* Prevent Valgrind warnings about writer_thread being
	uninitialized.  It does not matter if writer_thread is
	uninitialized, because we are comparing writer_thread against
	itself, and the operation should always succeed. */
	UNIV_MEM_VALID(&lock->writer_thread, sizeof lock->writer_thread);

	local_thread = lock->writer_thread;
	success = os_compare_and_swap_thread_id(
		&lock->writer_thread, local_thread, curr_thread);
	ut_a(success);
	lock->recursive = recursive;

#else /* INNODB_RW_LOCKS_USE_ATOMICS */

	mutex_enter(&lock->mutex);
	lock->writer_thread = curr_thread;
	lock->recursive = recursive;
	mutex_exit(&lock->mutex);

#endif /* INNODB_RW_LOCKS_USE_ATOMICS */
}

/******************************************************************//**
Low-level function which tries to lock an rw-lock in s-mode. Performs no
spinning.
@return	TRUE if success */
UNIV_INLINE
ibool
rw_lock_s_lock_low(
/*===============*/
	rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass __attribute__((unused)),
				/*!< in: pass value; != 0, if the lock will be
				passed to another thread to unlock */
	const char*	file_name, /*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
	if (!rw_lock_lock_word_decr(lock, 1)) {
		/* Locking did not succeed */
		return(FALSE);
	}

#ifdef UNIV_SYNC_DEBUG
	rw_lock_add_debug_info(lock, pass, RW_LOCK_SHARED, file_name, line);
#endif
	/* These debugging values are not set safely: they may be incorrect
	or even refer to a line that is invalid for the file name. */
	lock->last_s_file_name = file_name;
	lock->last_s_line = line;

	if (srv_instrument_semaphores) {
		lock->thread_id = os_thread_get_curr_id();
		lock->file_name = file_name;
		lock->line = line;
	}

	return(TRUE);	/* locking succeeded */
}

/******************************************************************//**
NOTE! Use the corresponding macro, not directly this function! Lock an
rw-lock in shared mode for the current thread. If the rw-lock is locked
in exclusive mode, or there is an exclusive lock request waiting, the
function spins a preset time (controlled by SYNC_SPIN_ROUNDS), waiting for
the lock, before suspending the thread. */
UNIV_INLINE
void
rw_lock_s_lock_func(
/*================*/
	rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the lock will
				be passed to another thread to unlock */
	const char*	file_name,/*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
	/* NOTE: As we do not know the thread ids for threads which have
	s-locked a latch, and s-lockers will be served only after waiting
	x-lock requests have been fulfilled, then if this thread already
	owns an s-lock here, it may end up in a deadlock with another thread
	which requests an x-lock here. Therefore, we will forbid recursive
	s-locking of a latch: the following assert will warn the programmer
	of the possibility of this kind of a deadlock. If we want to implement
	safe recursive s-locking, we should keep in a list the thread ids of
	the threads which have s-locked a latch. This would use some CPU
	time. */

#ifdef UNIV_SYNC_DEBUG
	ut_ad(!rw_lock_own(lock, RW_LOCK_SHARED)); /* see NOTE above */
	ut_ad(!rw_lock_own(lock, RW_LOCK_EX));
#endif /* UNIV_SYNC_DEBUG */

	if (rw_lock_s_lock_low(lock, pass, file_name, line)) {

		return; /* Success */
	} else {
		/* Did not succeed, try spin wait */

		rw_lock_s_lock_spin(lock, pass, false, false, file_name, line);

		return;
	}
}

/******************************************************************//**
Return true if waiters of higher priority than the current thread
exist.
@true if waiterss of higher priority exist */
UNIV_INLINE
bool
rw_lock_higher_prio_waiters_exist(
/*==============================*/
	bool	priority_lock,	/*!< in: whether the lock is a priority lock */
	bool	high_priority,	/*!< in: whether we are acquiring a priority
				lock with high priority */
	void*	lock)		/*!< in: rw lock */
{
	if (high_priority || !priority_lock) {
		ut_ad(!(!priority_lock && high_priority));
		return(false);
	}

	ut_ad(priority_lock && !high_priority);

	prio_rw_lock_t *prio_rw_lock = (prio_rw_lock_t *) lock;
	return prio_rw_lock->high_priority_wait_ex_waiter > 0
		|| prio_rw_lock->high_priority_s_waiters > 0
		|| prio_rw_lock->high_priority_x_waiters > 0;
}

/******************************************************************//**
NOTE! Use the corresponding macro, not directly this function, except if
you supply the file name and line number. Lock a priority rw-lock in shared
mode for the current thread, using the relative thread priority.  If the
rw-lock is locked in exclusive mode, or there is an exclusive lock request
waiting, the function spins a preset time (controlled by SYNC_SPIN_ROUNDS),
waiting for the lock, before suspending the thread. */
UNIV_INLINE
void
rw_lock_s_lock_func(
/*================*/
	prio_rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the lock will
				be passed to another thread to unlock */
	const char*	file_name,/*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad(!rw_lock_own(lock, RW_LOCK_SHARED)); /* see NOTE above */
	ut_ad(!rw_lock_own(lock, RW_LOCK_EX));
#endif /* UNIV_SYNC_DEBUG */

	bool	high_priority = srv_current_thread_priority > 0;

	/* Do not attempt to acquire a low-priority S latch if there are
	high-priority waiters even if such attempt would be successful.  This
	is to prevent a high priority X request from being starved by a
	sequence of overlapping regular priority S requests.  */

	if (!rw_lock_higher_prio_waiters_exist(true, high_priority, lock)
	    && rw_lock_s_lock_low(&lock->base_lock, pass, file_name, line)) {

		return; /* Success */
	} else {
		/* Did not succeed, try spin wait */
		rw_lock_s_lock_spin(lock, pass, true, high_priority, file_name,
				    line);

		return;
	}
}

/******************************************************************//**
NOTE! Use the corresponding macro, not directly this function! Lock an
rw-lock in exclusive mode for the current thread if the lock can be
obtained immediately.
@return	TRUE if success */
UNIV_INLINE
ibool
rw_lock_x_lock_func_nowait(
/*=======================*/
	rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	const char*	file_name,/*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
	ibool success;

#ifdef INNODB_RW_LOCKS_USE_ATOMICS
	success = os_compare_and_swap_lint(&lock->lock_word, X_LOCK_DECR, 0);
#else

	success = FALSE;
	mutex_enter(&(lock->mutex));
	if (lock->lock_word == X_LOCK_DECR) {
		lock->lock_word = 0;
		success = TRUE;
	}
	mutex_exit(&(lock->mutex));

#endif
	if (success) {
		rw_lock_set_writer_id_and_recursion_flag(lock, TRUE);

	} else if (lock->recursive
		   && os_thread_eq(lock->writer_thread,
				   os_thread_get_curr_id())) {
		/* Relock: this lock_word modification is safe since no other
		threads can modify (lock, unlock, or reserve) lock_word while
		there is an exclusive writer and this is the writer thread. */
		if (lock->lock_word == 0) {
			lock->lock_word = -X_LOCK_DECR;
		} else {
			lock->lock_word--;
		}

		/* Watch for too many recursive locks */
		ut_ad(lock->lock_word < 0);

	} else {
		/* Failure */
		return(FALSE);
	}
#ifdef UNIV_SYNC_DEBUG
	rw_lock_add_debug_info(lock, 0, RW_LOCK_EX, file_name, line);
#endif

	if (srv_instrument_semaphores) {
		lock->thread_id = os_thread_get_curr_id();
		lock->file_name = file_name;
		lock->line = line;
	}

	lock->last_x_file_name = file_name;
	lock->last_x_line = line;

	ut_ad(rw_lock_validate(lock));

	return(TRUE);
}

/******************************************************************//**
Releases a shared mode lock. */
UNIV_INLINE
void
rw_lock_s_unlock_func(
/*==================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the lock may have
				been passed to another thread to unlock */
#endif
	rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	ut_ad(lock->lock_word > -X_LOCK_DECR);
	ut_ad(lock->lock_word != 0);
	ut_ad(lock->lock_word < X_LOCK_DECR);

#ifdef UNIV_SYNC_DEBUG
	rw_lock_remove_debug_info(lock, pass, RW_LOCK_SHARED);
#endif

	/* Increment lock_word to indicate 1 less reader */
	if (rw_lock_lock_word_incr(lock, 1) == 0) {

		/* wait_ex waiter exists. It may not be asleep, but we signal
		anyway. We do not wake other waiters, because they can't
		exist without wait_ex waiter and wait_ex waiter goes first.*/
		os_event_set(lock->wait_ex_event);
		sync_array_object_signalled();

	}

	ut_ad(rw_lock_validate(lock));

#ifdef UNIV_SYNC_PERF_STAT
	rw_s_exit_count++;
#endif
}

/******************************************************************//**
Releases a shared mode priority lock. */
UNIV_INLINE
void
rw_lock_s_unlock_func(
/*==================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the lock may have
				  been passed to another thread to unlock */
#endif
	prio_rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	lint lock_word;

	ut_ad(lock->base_lock.lock_word > -X_LOCK_DECR);
	ut_ad(lock->base_lock.lock_word != 0);
	ut_ad(lock->base_lock.lock_word < X_LOCK_DECR);

#ifdef UNIV_SYNC_DEBUG
	rw_lock_remove_debug_info(&lock->base_lock, pass, RW_LOCK_SHARED);
#endif

	/* Increment lock_word to indicate 1 less reader */
	lock_word = rw_lock_lock_word_incr(&lock->base_lock, 1);
	if (lock_word == 0) {

		/* A waiting next-writer exists, either high priority or
		regular, sharing the same wait event.  */
		os_event_set(lock->base_lock.wait_ex_event);
		sync_array_object_signalled();

	} else if (lock_word == X_LOCK_DECR) {

		/* S-waiters may exist during an S unlock if a high-priority
		thread released it, because low-priority threads are prevented
		from acquiring S lock while high-priority thread holds it.  */
		if (lock->base_lock.waiters) {

			rw_lock_reset_waiter_flag(&lock->base_lock);
			os_event_set(lock->base_lock.event);
			sync_array_object_signalled();
		}
	}

	ut_ad(rw_lock_validate(lock));

#ifdef UNIV_SYNC_PERF_STAT
	rw_s_exit_count++;
#endif
}

/******************************************************************//**
Prepares an exclusive mode lock release: resets the recursion flag and removes
the debug information if needed  and returns the required lock word increment
value.
@return lock word increment value to perform the unlock */
UNIV_INLINE
ulint
rw_lock_x_prepare_unlock(
/*=====================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the lock may have
				been passed to another thread to unlock */
#endif
	rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	ut_ad(lock->lock_word == 0 || lock->lock_word <= -X_LOCK_DECR);

	/* lock->recursive flag also indicates if lock->writer_thread is
	valid or stale. If we are the last of the recursive callers
	then we must unset lock->recursive flag to indicate that the
	lock->writer_thread is now stale.
	Note that since we still hold the x-lock we can safely read the
	lock_word. */
	if (lock->lock_word == 0) {
		/* Last caller in a possible recursive chain. */
		lock->recursive = FALSE;
	}

#ifdef UNIV_SYNC_DEBUG
	rw_lock_remove_debug_info(lock, pass, RW_LOCK_EX);
#endif

	ulint x_lock_incr;
	if (lock->lock_word == 0) {
		x_lock_incr = X_LOCK_DECR;
	} else if (lock->lock_word == -X_LOCK_DECR) {
		x_lock_incr = X_LOCK_DECR;
	} else {
		ut_ad(lock->lock_word < -X_LOCK_DECR);
		x_lock_incr = 1;
	}

	return(x_lock_incr);
}

/******************************************************************//**
Releases an exclusive mode lock. */
UNIV_INLINE
void
rw_lock_x_unlock_func(
/*==================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the lock may have
				been passed to another thread to unlock */
#endif
	rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	ulint x_lock_incr = rw_lock_x_prepare_unlock(
#ifdef UNIV_SYNC_DEBUG
						     pass,
#endif
						     lock);

	if (rw_lock_lock_word_incr(lock, x_lock_incr) == X_LOCK_DECR) {
		/* Lock is now free. May have to signal read/write waiters.
		We do not need to signal wait_ex waiters, since they cannot
		exist when there is a writer. */

		if (lock->waiters) {
			rw_lock_reset_waiter_flag(lock);
			os_event_set(lock->event);
			sync_array_object_signalled();
		}
	}

	ut_ad(rw_lock_validate(lock));

#ifdef UNIV_SYNC_PERF_STAT
	rw_x_exit_count++;
#endif
}

/******************************************************************//**
Releases an exclusive mode priority lock. */
UNIV_INLINE
void
rw_lock_x_unlock_func(
/*==================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the lock may have
				been passed to another thread to unlock */
#endif
	prio_rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	ulint x_lock_incr = rw_lock_x_prepare_unlock(
#ifdef UNIV_SYNC_DEBUG
						     pass,
#endif
						     &lock->base_lock);

	ut_ad(lock->high_priority_wait_ex_waiter == 0);

	if (rw_lock_lock_word_incr(&lock->base_lock, x_lock_incr)
	    == X_LOCK_DECR) {

		/* Priority lock is now free.  Signal any waiters in this
	        order: 1) high priority X waiters; 2) high priority S waiters;
	        3) regular priority waiters.
		We do not need to signal wait_ex waiters, since they cannot
		exist when there is a writer. */

		if (lock->high_priority_x_waiters) {

			os_event_set(lock->high_priority_x_event);
			sync_array_object_signalled();
		} else if (lock->high_priority_s_waiters) {

			os_event_set(lock->high_priority_s_event);
			sync_array_object_signalled();
		} else if (lock->base_lock.waiters) {

			rw_lock_reset_waiter_flag(&lock->base_lock);
			os_event_set(lock->base_lock.event);
			sync_array_object_signalled();
		}
	}

	ut_ad(rw_lock_validate(lock));

#ifdef UNIV_SYNC_PERF_STAT
	rw_x_exit_count++;
#endif
}

#ifdef UNIV_PFS_RWLOCK

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_create_func().
NOTE! Please use the corresponding macro rw_lock_create(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_create_func(
/*====================*/
	mysql_pfs_key_t	key,		/*!< in: key registered with
					performance schema */
	rw_lock_t*	lock,		/*!< in: pointer to memory */
# ifdef UNIV_DEBUG
#  ifdef UNIV_SYNC_DEBUG
	ulint		level,		/*!< in: level */
#  endif /* UNIV_SYNC_DEBUG */
# endif /* UNIV_DEBUG */
	const char*	cmutex_name,	/*!< in: mutex name */
	const char*	cfile_name,	/*!< in: file name where created */
	ulint		cline)		/*!< in: file line where created */
{
	/* Initialize the rwlock for performance schema */
	lock->pfs_psi = PSI_RWLOCK_CALL(init_rwlock)(key, lock);

	/* The actual function to initialize an rwlock */
	rw_lock_create_func(lock,
# ifdef UNIV_DEBUG
#  ifdef UNIV_SYNC_DEBUG
			    level,
#  endif /* UNIV_SYNC_DEBUG */
# endif /* UNIV_DEBUG */
			    cmutex_name,
			    cfile_name,
			    cline);
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_create_func().
NOTE! Please use the corresponding macro rw_lock_create(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_create_func(
/*====================*/
	mysql_pfs_key_t	key,		/*!< in: key registered with
					performance schema */
	prio_rw_lock_t*	lock,		/*!< in: pointer to memory */
# ifdef UNIV_DEBUG
#  ifdef UNIV_SYNC_DEBUG
	ulint		level,		/*!< in: level */
#  endif /* UNIV_SYNC_DEBUG */
# endif /* UNIV_DEBUG */
	const char*	cmutex_name,	/*!< in: mutex name */
	const char*	cfile_name,	/*!< in: file name where created */
	ulint		cline)		/*!< in: file line where created */
{
	/* Initialize the rwlock for performance schema */
	lock->base_lock.pfs_psi = PSI_RWLOCK_CALL(init_rwlock)(key, lock);

	/* The actual function to initialize an rwlock */
	rw_lock_create_func(lock,
# ifdef UNIV_DEBUG
#  ifdef UNIV_SYNC_DEBUG
			    level,
#  endif /* UNIV_SYNC_DEBUG */
# endif /* UNIV_DEBUG */
			    cmutex_name,
			    cfile_name,
			    cline);
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_x_lock_func()
NOTE! Please use the corresponding macro rw_lock_x_lock(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_x_lock_func(
/*====================*/
	rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the lock will
				be passed to another thread to unlock */
	const char*	file_name,/*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
	if (lock->pfs_psi != NULL)
	{
		PSI_rwlock_locker*	locker;
		PSI_rwlock_locker_state	state;

		/* Record the entry of rw x lock request in performance schema */
		locker = PSI_RWLOCK_CALL(start_rwlock_wrwait)(
			&state, lock->pfs_psi, PSI_RWLOCK_WRITELOCK,
			file_name, static_cast<uint>(line));

		rw_lock_x_lock_func(
			lock, pass, file_name, static_cast<uint>(line));

		if (locker != NULL) {
			PSI_RWLOCK_CALL(end_rwlock_wrwait)(locker, 0);
		}
	}
	else
	{
		rw_lock_x_lock_func(lock, pass, file_name, line);
	}
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_x_lock_func()
NOTE! Please use the corresponding macro rw_lock_x_lock(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_x_lock_func(
/*====================*/
	prio_rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the lock will
				be passed to another thread to unlock */
	const char*	file_name,/*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
	if (lock->base_lock.pfs_psi != NULL)
	{
		PSI_rwlock_locker*	locker;
		PSI_rwlock_locker_state	state;

		/* Record the entry of rw x lock request in performance schema */
		locker = PSI_RWLOCK_CALL(start_rwlock_wrwait)(
			&state, lock->base_lock.pfs_psi, PSI_RWLOCK_WRITELOCK,
			file_name, line);

		rw_lock_x_lock_func(lock, pass, file_name, line);

		if (locker != NULL) {
			PSI_RWLOCK_CALL(end_rwlock_wrwait)(locker, 0);
		}
	}
	else
	{
		rw_lock_x_lock_func(lock, pass, file_name, line);
	}
}

/******************************************************************//**
Performance schema instrumented wrap function for
rw_lock_x_lock_func_nowait()
NOTE! Please use the corresponding macro rw_lock_x_lock_func(),
not directly this function!
@return	TRUE if success */
UNIV_INLINE
ibool
pfs_rw_lock_x_lock_func_nowait(
/*===========================*/
	rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	const char*	file_name,/*!< in: file name where lock
				requested */
	ulint		line)	/*!< in: line where requested */
{
	ibool	ret;

	if (lock->pfs_psi != NULL)
	{
		PSI_rwlock_locker*	locker;
		PSI_rwlock_locker_state		state;

		/* Record the entry of rw x lock request in performance schema */
		locker = PSI_RWLOCK_CALL(start_rwlock_wrwait)(
			&state, lock->pfs_psi, PSI_RWLOCK_WRITELOCK,
			file_name, static_cast<uint>(line));

		ret = rw_lock_x_lock_func_nowait(lock, file_name, line);

		if (locker != NULL) {
			PSI_RWLOCK_CALL(end_rwlock_wrwait)(
				locker, static_cast<int>(ret));
		}
	}
	else
	{
		ret = rw_lock_x_lock_func_nowait(lock, file_name, line);
	}

	return(ret);
}
/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_free_func()
NOTE! Please use the corresponding macro rw_lock_free(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_free_func(
/*==================*/
	rw_lock_t*	lock)	/*!< in: pointer to rw-lock */
{
	if (lock->pfs_psi != NULL)
	{
		PSI_RWLOCK_CALL(destroy_rwlock)(lock->pfs_psi);
		lock->pfs_psi = NULL;
	}

	rw_lock_free_func(lock);
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_free_func()
NOTE! Please use the corresponding macro rw_lock_free(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_free_func(
/*==================*/
	prio_rw_lock_t*	lock)	/*!< in: pointer to rw-lock */
{
	if (lock->base_lock.pfs_psi != NULL)
	{
		PSI_RWLOCK_CALL(destroy_rwlock)(lock->base_lock.pfs_psi);
		lock->base_lock.pfs_psi = NULL;
	}

	rw_lock_free_func(lock);
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_s_lock_func()
NOTE! Please use the corresponding macro rw_lock_s_lock(), not
directly this function! */
UNIV_INLINE
void
pfs_rw_lock_s_lock_func(
/*====================*/
	rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the
				lock will be passed to another
				thread to unlock */
	const char*	file_name,/*!< in: file name where lock
				requested */
	ulint		line)	/*!< in: line where requested */
{
	if (lock->pfs_psi != NULL)
	{
		PSI_rwlock_locker*	locker;
		PSI_rwlock_locker_state	state;

		/* Instrumented to inform we are aquiring a shared rwlock */
		locker = PSI_RWLOCK_CALL(start_rwlock_rdwait)(
			&state, lock->pfs_psi, PSI_RWLOCK_READLOCK,
			file_name, static_cast<uint>(line));

		rw_lock_s_lock_func(lock, pass, file_name, line);

		if (locker != NULL) {
			PSI_RWLOCK_CALL(end_rwlock_rdwait)(locker, 0);
		}
	}
	else
	{
		rw_lock_s_lock_func(lock, pass, file_name, line);
	}

	return;
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_s_lock_func()
NOTE! Please use the corresponding macro rw_lock_s_lock(), not
directly this function! */
UNIV_INLINE
void
pfs_rw_lock_s_lock_func(
/*====================*/
	prio_rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the
				lock will be passed to another
				thread to unlock */
	const char*	file_name,/*!< in: file name where lock
				requested */
	ulint		line)	/*!< in: line where requested */
{
	if (lock->base_lock.pfs_psi != NULL)
	{
		PSI_rwlock_locker*	locker;
		PSI_rwlock_locker_state	state;

		/* Instrumented to inform we are aquiring a shared rwlock */
		locker = PSI_RWLOCK_CALL(start_rwlock_rdwait)(
			&state, lock->base_lock.pfs_psi, PSI_RWLOCK_READLOCK,
			file_name, line);

		rw_lock_s_lock_func(lock, pass, file_name, line);

		if (locker != NULL) {
			PSI_RWLOCK_CALL(end_rwlock_rdwait)(locker, 0);
		}
	}
	else
	{
		rw_lock_s_lock_func(lock, pass, file_name, line);
	}

	return;
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_s_lock_func()
NOTE! Please use the corresponding macro rw_lock_s_lock(), not
directly this function!
@return	TRUE if success */
UNIV_INLINE
ibool
pfs_rw_lock_s_lock_low(
/*===================*/
	rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the
				lock will be passed to another
				thread to unlock */
	const char*	file_name, /*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
	ibool	ret;

	if (lock->pfs_psi != NULL)
	{
		PSI_rwlock_locker*	locker;
		PSI_rwlock_locker_state	state;

		/* Instrumented to inform we are aquiring a shared rwlock */
		locker = PSI_RWLOCK_CALL(start_rwlock_rdwait)(
			&state, lock->pfs_psi, PSI_RWLOCK_READLOCK,
			file_name, static_cast<uint>(line));

		ret = rw_lock_s_lock_low(lock, pass, file_name, line);

		if (locker != NULL) {
			PSI_RWLOCK_CALL(end_rwlock_rdwait)(
				locker, static_cast<int>(ret));
		}
	}
	else
	{
		ret = rw_lock_s_lock_low(lock, pass, file_name, line);
	}

	return(ret);
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_s_lock_func()
NOTE! Please use the corresponding macro rw_lock_s_lock(), not
directly this function!
@return	TRUE if success */
UNIV_INLINE
ibool
pfs_rw_lock_s_lock_low(
/*===================*/
	prio_rw_lock_t*	lock,	/*!< in: pointer to rw-lock */
	ulint		pass,	/*!< in: pass value; != 0, if the
				  lock will be passed to another
				  thread to unlock */
	const char*	file_name, /*!< in: file name where lock requested */
	ulint		line)	/*!< in: line where requested */
{
	return(pfs_rw_lock_s_lock_low(&lock->base_lock, pass,
				      file_name, line));
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_x_unlock_func()
NOTE! Please use the corresponding macro rw_lock_x_unlock(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_x_unlock_func(
/*======================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the
				lock may have been passed to another
				thread to unlock */
#endif
	rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	/* Inform performance schema we are unlocking the lock */
	if (lock->pfs_psi != NULL)
		PSI_RWLOCK_CALL(unlock_rwlock)(lock->pfs_psi);

	rw_lock_x_unlock_func(
#ifdef UNIV_SYNC_DEBUG
		pass,
#endif
		lock);
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_x_unlock_func()
NOTE! Please use the corresponding macro rw_lock_x_unlock(), not directly
this function! */
UNIV_INLINE
void
pfs_rw_lock_x_unlock_func(
/*======================*/
#ifdef UNIV_SYNC_DEBUG
		ulint		pass,	/*!< in: pass value; != 0, if the
					lock may have been passed to another
					thread to unlock */
#endif
		prio_rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	/* Inform performance schema we are unlocking the lock */
	if (lock->base_lock.pfs_psi != NULL)
		PSI_RWLOCK_CALL(unlock_rwlock)(lock->base_lock.pfs_psi);

	rw_lock_x_unlock_func(
#ifdef UNIV_SYNC_DEBUG
		pass,
#endif
		lock);
}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_s_unlock_func()
NOTE! Please use the corresponding macro pfs_rw_lock_s_unlock(), not
directly this function! */
UNIV_INLINE
void
pfs_rw_lock_s_unlock_func(
/*======================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the
				lock may have been passed to another
				thread to unlock */
#endif
	rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	/* Inform performance schema we are unlocking the lock */
	if (lock->pfs_psi != NULL)
		PSI_RWLOCK_CALL(unlock_rwlock)(lock->pfs_psi);

	rw_lock_s_unlock_func(
#ifdef UNIV_SYNC_DEBUG
		pass,
#endif
		lock);

}

/******************************************************************//**
Performance schema instrumented wrap function for rw_lock_s_unlock_func()
NOTE! Please use the corresponding macro pfs_rw_lock_s_unlock(), not
directly this function! */
UNIV_INLINE
void
pfs_rw_lock_s_unlock_func(
/*======================*/
#ifdef UNIV_SYNC_DEBUG
	ulint		pass,	/*!< in: pass value; != 0, if the
				  lock may have been passed to another
				  thread to unlock */
#endif
	prio_rw_lock_t*	lock)	/*!< in/out: rw-lock */
{
	/* Inform performance schema we are unlocking the lock */
	if (lock->base_lock.pfs_psi != NULL)
		PSI_RWLOCK_CALL(unlock_rwlock)(lock->base_lock.pfs_psi);

	rw_lock_s_unlock_func(
#ifdef UNIV_SYNC_DEBUG
		pass,
#endif
		lock);

}

#endif /* UNIV_PFS_RWLOCK */