#include "univ.i"
#include "ut0lst.h"
#include "ut0counter.h"
#include "sync0sync.h"
#include "os0sync.h"
#include "sync0rw.ic"

Include dependency graph for sync0rw.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	rw_lock_stats_t
struct	rw_lock_t
struct	rw_lock_debug_t

Macros
#define	RW_S_LATCH 1
#define	RW_X_LATCH 2
#define	RW_NO_LATCH 3
#define	X_LOCK_DECR 0x00100000
#define	rw_lock_create(K, L, level) rw_lock_create_func((L), (level), #L, __FILE__, __LINE__)
#define	rw_lock_s_lock(M) rw_lock_s_lock_func((M), 0, __FILE__, __LINE__)
#define	rw_lock_s_lock_inline(M, P, F, L) rw_lock_s_lock_func((M), (P), (F), (L))
#define	rw_lock_s_lock_gen(M, P) rw_lock_s_lock_func((M), (P), __FILE__, __LINE__)
#define	rw_lock_s_lock_gen_nowait(M, P) rw_lock_s_lock_low((M), (P), __FILE__, __LINE__)
#define	rw_lock_s_lock_nowait(M, F, L) rw_lock_s_lock_low((M), 0, (F), (L))
#define	rw_lock_s_unlock_gen(L, P) rw_lock_s_unlock_func(P, L)
#define	rw_lock_x_lock(M) rw_lock_x_lock_func((M), 0, __FILE__, __LINE__)
#define	rw_lock_x_lock_inline(M, P, F, L) rw_lock_x_lock_func((M), (P), (F), (L))
#define	rw_lock_x_lock_gen(M, P) rw_lock_x_lock_func((M), (P), __FILE__, __LINE__)
#define	rw_lock_x_lock_nowait(M) rw_lock_x_lock_func_nowait((M), __FILE__, __LINE__)
#define	rw_lock_x_lock_func_nowait_inline(M, F, L) rw_lock_x_lock_func_nowait((M), (F), (L))
#define	rw_lock_x_unlock_gen(L, P) rw_lock_x_unlock_func(P, L)
#define	rw_lock_free(M) rw_lock_free_func(M)
#define	rw_lock_s_unlock(L) rw_lock_s_unlock_gen(L, 0)
#define	rw_lock_x_unlock(L) rw_lock_x_unlock_gen(L, 0)
#define	RW_LOCK_MAGIC_N 22643

Typedefs
typedef ut_list_base< rw_lock_t >	rw_lock_list_t

Functions
UNIV_INTERN void	rw_lock_create_func (rw_lock_t lock, ulint level, const char cmutex_name, const char *cfile_name, ulint cline)
UNIV_INTERN void	rw_lock_free_func (rw_lock_t *lock)
UNIV_INTERN ibool	rw_lock_validate (rw_lock_t *lock)
UNIV_INLINE ibool	rw_lock_s_lock_low (rw_lock_t *lock, ulint pass)
UNIV_INLINE void	rw_lock_s_lock_func (rw_lock_t lock, ulint pass, const char file_name, ulint line)
UNIV_INLINE ibool	rw_lock_x_lock_func_nowait (rw_lock_t lock, const char file_name, ulint line)
UNIV_INLINE void	rw_lock_s_unlock_func (ulint pass, rw_lock_t *lock)
UNIV_INTERN void	rw_lock_x_lock_func (rw_lock_t lock, ulint pass, const char file_name, ulint line)
UNIV_INLINE void	rw_lock_x_unlock_func (ulint pass, rw_lock_t *lock)
UNIV_INTERN void	rw_lock_x_lock_move_ownership (rw_lock_t *lock)
UNIV_INLINE ulint	rw_lock_get_x_lock_count (const rw_lock_t *lock)
UNIV_INLINE ulint	rw_lock_get_waiters (const rw_lock_t *lock)
UNIV_INLINE ulint	rw_lock_get_writer (const rw_lock_t *lock)
UNIV_INLINE ulint	rw_lock_get_reader_count (const rw_lock_t *lock)
UNIV_INLINE ibool	rw_lock_lock_word_decr (rw_lock_t *lock, ulint amount)
UNIV_INLINE lint	rw_lock_lock_word_incr (rw_lock_t *lock, ulint amount)
UNIV_INLINE void	rw_lock_set_writer_id_and_recursion_flag (rw_lock_t *lock, ibool recursive)
UNIV_INTERN ibool	rw_lock_own (rw_lock_t *lock, ulint lock_type))
UNIV_INTERN ibool	rw_lock_is_locked (rw_lock_t *lock, ulint lock_type)
UNIV_INTERN void	rw_lock_print (rw_lock_t *lock)
UNIV_INTERN void	rw_lock_list_print_info (FILE *file)
UNIV_INTERN ulint	rw_lock_n_locked (void)
UNIV_INTERN void	rw_lock_debug_mutex_enter (void)
UNIV_INTERN void	rw_lock_debug_mutex_exit (void)
UNIV_INTERN void	rw_lock_debug_print (FILE f, rw_lock_debug_t info)

Variables
rw_lock_list_t	rw_lock_list
ib_mutex_t	rw_lock_list_mutex
ib_mutex_t	rw_lock_debug_mutex
os_event_t	rw_lock_debug_event
ibool	rw_lock_debug_waiters
rw_lock_stats_t	rw_lock_stats
UNIV_INLINE ibool const char *	file_name
UNIV_INLINE ibool const char ulint	line

Detailed Description

The read-write lock (for threads, not for database transactions)

Created 9/11/1995 Heikki Tuuri

Macro Definition Documentation

#define rw_lock_create	(	K,
		L,
		level
	)	rw_lock_create_func((L), (level), #L, __FILE__, __LINE__)

Creates, or rather, initializes an rw-lock object in a specified memory location (which must be appropriately aligned). The rw-lock is initialized to the non-locked state. Explicit freeing of the rw-lock with rw_lock_free is necessary only if the memory block containing it is freed. if MySQL performance schema is enabled and "UNIV_PFS_RWLOCK" is defined, the rwlock are instrumented with performance schema probes.

#define RW_LOCK_MAGIC_N 22643

Value of rw_lock_t::magic_n

#define rw_lock_s_lock ( M ) rw_lock_s_lock_func((M), 0, __FILE__, __LINE__)

NOTE! The following macros should be used in rw locking and unlocking, not the corresponding function.

Function Documentation

UNIV_INTERN void rw_lock_create_func	(	rw_lock_t *	lock,
		ulint	level,
		const char *	cmutex_name,
		const char *	cfile_name,
		ulint	cline
	)

Creates, or rather, initializes an rw-lock object in a specified memory location (which must be appropriately aligned). The rw-lock is initialized to the non-locked state. Explicit freeing of the rw-lock with rw_lock_free is necessary only if the memory block containing it is freed. in: file line where created

Parameters

lock	in: pointer to memory
level	in: level
cmutex_name	in: mutex name
cfile_name	in: file name where created

UNIV_INTERN void rw_lock_debug_mutex_enter ( void )

Acquires the debug mutex. We cannot use the mutex defined in sync0sync, because the debug mutex is also acquired in sync0arr while holding the OS mutex protecting the sync array, and the ordinary mutex_enter might recursively call routines in sync0arr, leading to a deadlock on the OS mutex.

UNIV_INTERN void rw_lock_debug_mutex_exit ( void )

Releases the debug mutex.

UNIV_INTERN void rw_lock_debug_print	(	FILE *	f,
		rw_lock_debug_t *	info
	)

Prints info of a debug struct. in: debug struct

Parameters

f	in: output stream

UNIV_INTERN void rw_lock_free_func ( rw_lock_t * lock )

Calling this function is obligatory only if the memory buffer containing the rw-lock is freed. Removes an rw-lock object from the global list. The rw-lock is checked to be in the non-locked state. in: rw-lock

UNIV_INLINE ulint rw_lock_get_reader_count ( const rw_lock_t * lock )

Returns the number of readers.

Returns: number of readers in: rw-lock

Returns the number of readers.

Returns: number of readers

Parameters

lock	in: rw-lock

UNIV_INLINE ulint rw_lock_get_waiters ( const rw_lock_t * lock )

Check if there are threads waiting for the rw-lock.

Returns: 1 if waiters, 0 otherwise in: rw-lock

Check if there are threads waiting for the rw-lock.

Returns: 1 if waiters, 0 otherwise

Parameters

lock	in: rw-lock

UNIV_INLINE ulint rw_lock_get_writer ( const rw_lock_t * lock )

Returns the write-status of the lock - this function made more sense with the old rw_lock implementation.

Returns: RW_LOCK_NOT_LOCKED, RW_LOCK_EX, RW_LOCK_WAIT_EX in: rw-lock

Returns the write-status of the lock - this function made more sense with the old rw_lock implementation.

Returns: RW_LOCK_NOT_LOCKED, RW_LOCK_EX, RW_LOCK_WAIT_EX

Parameters

lock	in: rw-lock

UNIV_INLINE ulint rw_lock_get_x_lock_count ( const rw_lock_t * lock )

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.

Returns: value of writer_count in: rw-lock

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.

Returns: value of writer_count

Parameters

lock	in: rw-lock

UNIV_INTERN ibool rw_lock_is_locked	(	rw_lock_t *	lock,
		ulint	lock_type
	)

Checks if somebody has locked the rw-lock in the specified mode. in: lock type: RW_LOCK_SHARED, RW_LOCK_EX

Parameters

lock	in: rw-lock

UNIV_INTERN void rw_lock_list_print_info ( FILE * file )

Prints debug info of currently locked rw-locks. in: file where to print

UNIV_INLINE ibool rw_lock_lock_word_decr	(	rw_lock_t *	lock,
		ulint	amount
	)

Decrements lock_word the specified amount if it is greater than 0. This is used by both s_lock and x_lock operations.

Returns: TRUE if decr occurs in: amount to decrement

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.

Returns: TRUE if decr occurs

Parameters

lock	in/out: rw-lock
amount	in: amount to decrement

UNIV_INLINE lint rw_lock_lock_word_incr	(	rw_lock_t *	lock,
		ulint	amount
	)

Increments lock_word the specified amount and returns new value.

Returns: lock->lock_word after increment in: amount to increment

Increments lock_word the specified amount and returns new value.

Returns: lock->lock_word after increment

Parameters

lock	in/out: rw-lock
amount	in: amount of increment

UNIV_INTERN ulint rw_lock_n_locked ( void )

Returns the number of currently locked rw-locks. Works only in the debug version.

Returns: number of locked rw-locks

UNIV_INTERN ibool rw_lock_own	(	rw_lock_t *	lock,
		ulint	lock_type
	)

Checks if the thread has locked the rw-lock in the specified mode, with the pass value == 0.

Parameters

lock	in: rw-lock
lock_type	in: lock type: RW_LOCK_SHARED, RW_LOCK_EX

UNIV_INTERN void rw_lock_print ( rw_lock_t * lock )

Prints debug info of an rw-lock. in: rw-lock

UNIV_INLINE void rw_lock_s_lock_func	(	rw_lock_t *	lock,
		ulint	pass,
		const char *	file_name,
		ulint	line
	)

NOTE! Use the corresponding macro, not directly this function, except if you supply the file name and line number. 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. in: line where requested

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.

Parameters

lock	in: pointer to rw-lock
pass	in: pass value; != 0, if the lock will be passed to another thread to unlock
file_name	in: file name where lock requested
line	in: line where requested

UNIV_INLINE ibool rw_lock_s_lock_low	(	rw_lock_t *	lock,
		ulint	pass
	)

Low-level function which tries to lock an rw-lock in s-mode. Performs no spinning.

Returns: TRUE if success

Parameters

lock	in: pointer to rw-lock

UNIV_INLINE void rw_lock_s_unlock_func	(	ulint	pass,
		rw_lock_t *	lock
	)

Releases a shared mode lock. in/out: rw-lock

Releases a shared mode lock.

Parameters

pass	in: pass value; != 0, if the lock may have been passed to another thread to unlock
lock	in/out: rw-lock

UNIV_INLINE void rw_lock_set_writer_id_and_recursion_flag	(	rw_lock_t *	lock,
		ibool	recursive
	)

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. in: TRUE if recursion allowed

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.

Parameters

lock	in/out: lock to work on
recursive	in: TRUE if recursion allowed

UNIV_INTERN ibool rw_lock_validate ( rw_lock_t * lock )

Checks that the rw-lock has been initialized and that there are no simultaneous shared and exclusive locks.

Returns: TRUE in: rw-lock

UNIV_INTERN void rw_lock_x_lock_func	(	rw_lock_t *	lock,
		ulint	pass,
		const char *	file_name,
		ulint	line
	)

NOTE! Use the corresponding macro, not directly this function! Lock an rw-lock in exclusive mode for the current thread. If the rw-lock is locked in shared or 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. If the same thread has an x-lock on the rw-lock, locking succeed, with the following exception: if pass != 0, only a single x-lock may be taken on the lock. NOTE: If the same thread has an s-lock, locking does not succeed! in: line where requested

Parameters

lock	in: pointer to rw-lock
pass	in: pass value; != 0, if the lock will be passed to another thread to unlock
file_name	in: file name where lock requested

UNIV_INLINE ibool rw_lock_x_lock_func_nowait	(	rw_lock_t *	lock,
		const char *	file_name,
		ulint	line
	)

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.

Returns: TRUE if success in: line where requested

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.

Returns: TRUE if success

Parameters

lock	in: pointer to rw-lock
file_name	in: file name where lock requested
line	in: line where requested

UNIV_INTERN void rw_lock_x_lock_move_ownership ( rw_lock_t * lock )

This function is used in the insert buffer to move the ownership of an x-latch on a buffer frame to the current thread. The x-latch was set by the buffer read operation and it protected the buffer frame while the read was done. The ownership is moved because we want that the current thread is able to acquire a second x-latch which is stored in an mtr. This, in turn, is needed to pass the debug checks of index page operations. in: lock which was x-locked in the buffer read

UNIV_INLINE void rw_lock_x_unlock_func	(	ulint	pass,
		rw_lock_t *	lock
	)

Releases an exclusive mode lock. in/out: rw-lock

Releases an exclusive mode lock.

Parameters

pass	in: pass value; != 0, if the lock may have been passed to another thread to unlock
lock	in/out: rw-lock

Variable Documentation

UNIV_INLINE ibool const char* file_name

< in: pass value; != 0, if the lock will be passed to another thread to unlock in: file name where lock requested

UNIV_INLINE ibool const char ulint line

in: line where requested

os_event_t rw_lock_debug_event

If deadlock detection does not get immediately the mutex it may wait for this event

ibool rw_lock_debug_waiters

This is set to TRUE, if there may be waiters for the event

rw_lock_stats_t rw_lock_stats

Counters for RW locks.

Data Structures

Macros

Typedefs

Functions

Variables

Detailed Description

Macro Definition Documentation

Function Documentation

Variable Documentation