The read-write lock (for thread synchronization) More...

#include "sync0rw.h"
#include <my_sys.h>
#include <sys/types.h>
#include "ha_prototypes.h"
#include "mem0mem.h"
#include "os0event.h"
#include "os0thread.h"
#include "srv0mon.h"
#include "srv0srv.h"
#include "sync0debug.h"

Typedefs
typedef std::vector< const rw_lock_debug_t * >	Infos
	For collecting the debug information for a thread's rw-lock. More...

Functions
static rw_lock_debug_t *	rw_lock_debug_create (void)
	Creates a debug info struct. More...

static void	rw_lock_debug_free (rw_lock_debug_t *info)
	Frees a debug info struct. More...

void	rw_lock_create_func (rw_lock_t *lock, latch_id_t id, ut::Location clocation)
	Creates, or rather, initializes an rw-lock object in a specified memory location (which must be appropriately aligned). More...

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. More...

void	rw_lock_s_lock_spin (rw_lock_t *lock, ulint pass, ut::Location location)
	Lock an rw-lock in shared mode for the current thread. More...

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. More...

static void	rw_lock_x_lock_wait_func (rw_lock_t lock, ulint pass, lint threshold, const char file_name, ulint line)
	Function for the next writer to call. More...

static void	rw_lock_x_lock_wait (rw_lock_t lock, ulint pass, lint treshold, const char file_name, ulint line)
	Function for the next writer to call. More...

static bool	rw_lock_x_lock_low (rw_lock_t lock, ulint pass, const char file_name, ulint line)
	Low-level function for acquiring an exclusive lock. More...

bool	rw_lock_sx_lock_low (rw_lock_t *lock, ulint pass, ut::Location location)
	Low-level function for acquiring an sx lock. More...

void	rw_lock_x_lock_func (rw_lock_t *lock, ulint pass, ut::Location location)
	NOTE! Use the corresponding macro, not directly this function! Lock an rw-lock in exclusive mode for the current thread. More...

void	rw_lock_sx_lock_func (rw_lock_t *lock, ulint pass, ut::Location location)
	NOTE! Use the corresponding macro, not directly this function! Lock an rw-lock in SX mode for the current thread. More...

bool	rw_lock_validate (const rw_lock_t *lock)
	Checks that the rw-lock has been initialized and that there are no simultaneous shared and exclusive locks. More...

bool	rw_lock_is_locked (rw_lock_t *lock, ulint lock_type)
	Checks if somebody has locked the rw-lock in the specified mode. More...

void	rw_lock_add_debug_info (rw_lock_t *lock, ulint pass, ulint lock_type, ut::Location location)
	Inserts the debug information for an rw-lock. More...

void	rw_lock_remove_debug_info (rw_lock_t *lock, ulint pass, ulint lock_type)
	Removes a debug information struct for an rw-lock. More...

bool	rw_lock_own (const 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. More...

static void	rw_lock_get_debug_info (const rw_lock_t lock, Infos infos)
	Get the thread debug info. More...

bool	rw_lock_own_flagged (const rw_lock_t *lock, rw_lock_flags_t flags)
	Checks if the thread has locked the rw-lock in the specified mode, with the pass value == 0. More...

void	rw_lock_list_print_info (FILE *file)
	Prints debug info of currently locked rw-locks. More...

void	rw_lock_debug_print (FILE f, const rw_lock_debug_t info)
	Prints info of a debug struct. More...

Variables
rw_lock_list_t	rw_lock_list {}
	The global list of rw-locks. More...

ib_mutex_t	rw_lock_list_mutex

Detailed Description

The read-write lock (for thread synchronization)

Created 9/11/1995 Heikki Tuuri

Typedef Documentation

◆ Infos

typedef std::vector<const rw_lock_debug_t *> Infos

For collecting the debug information for a thread's rw-lock.

Function Documentation

◆ rw_lock_add_debug_info()

void rw_lock_add_debug_info	(	rw_lock_t *	lock,
		ulint	pass,
		ulint	lock_type,
		ut::Location	location
	)

Inserts the debug information for an rw-lock.

Parameters

[in]	lock	rw-lock
[in]	pass	pass value
[in]	lock_type	lock type
[in]	location	location where requested

◆ rw_lock_create_func()

void rw_lock_create_func	(	rw_lock_t *	lock,
		latch_id_t	id,
		ut::Location	clocation
	)

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.

Parameters

[in]	lock	pointer to memory
[in]	id	latch_id
[in]	clocation	location where created

◆ rw_lock_debug_create()

static rw_lock_debug_t * rw_lock_debug_create ( void )

static

Creates a debug info struct.

Returns: own: debug info struct

◆ rw_lock_debug_free()

static void rw_lock_debug_free ( rw_lock_debug_t * info )

static

Frees a debug info struct.

◆ rw_lock_debug_print()

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

Prints info of a debug struct.

Parameters

[in]	f	Output stream
[in]	info	Debug struct

◆ rw_lock_free_func()

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.

Parameters

lock	in/out: rw-lock

◆ rw_lock_get_debug_info()

static void rw_lock_get_debug_info	(	const rw_lock_t *	lock,
		Infos *	infos
	)

static

Get the thread debug info.

Parameters

[in]	infos	The rw-lock mode owned by the threads
[in]	lock	rw-lock to check

◆ rw_lock_is_locked()

bool rw_lock_is_locked	(	rw_lock_t *	lock,
		ulint	lock_type
	)

Checks if somebody has locked the rw-lock in the specified mode.

Returns: true if locked

Parameters

lock	in: rw-lock
lock_type	in: lock type: RW_LOCK_S, RW_LOCK_X or RW_LOCK_SX

◆ rw_lock_list_print_info()

void rw_lock_list_print_info ( FILE * file )

Prints debug info of currently locked rw-locks.

Parameters

[in] file file where to print

Parameters

file	in: file where to print

◆ rw_lock_own()

bool rw_lock_own	(	const 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.

Note that the mode is checked exactly, so if the thread owns RW_LOCK_X only, the rw_lock_own(..,RW_LOCK_S) will return false.

Parameters

[in]	lock	the rw-lock
[in]	lock_type	The exact lock type to check: RW_LOCK_S, RW_LOCK_SX or RW_LOCK_X

◆ rw_lock_own_flagged()

bool rw_lock_own_flagged	(	const rw_lock_t *	lock,
		rw_lock_flags_t	flags
	)

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

Parameters

[in]	lock	rw-lock
[in]	flags	specify lock types with OR of the rw_lock_flag_t values

Returns: true if locked

◆ rw_lock_remove_debug_info()

void rw_lock_remove_debug_info	(	rw_lock_t *	lock,
		ulint	pass,
		ulint	lock_type
	)

Removes a debug information struct for an rw-lock.

in: lock type

Parameters

lock	in: rw-lock
pass	in: pass value
lock_type	in: lock type

◆ rw_lock_s_lock_spin()

void rw_lock_s_lock_spin	(	rw_lock_t *	lock,
		ulint	pass,
		ut::Location	location
	)

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 srv_n_spin_wait_rounds), waiting for the lock before suspending the thread.

Parameters

[in]	lock	pointer to rw-lock
[in]	pass	pass value; !=0, if the lock will be passed to another thread to unlock
[in]	location	location where requested

◆ rw_lock_sx_lock_func()

void rw_lock_sx_lock_func	(	rw_lock_t *	lock,
		ulint	pass,
		ut::Location	location
	)

NOTE! Use the corresponding macro, not directly this function! Lock an rw-lock in SX 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. If the same thread has an x-lock on the rw-lock, locking succeed, with the following exception: if pass != 0, only a single sx-lock may be taken on the lock. NOTE: If the same thread has an s-lock, locking does not succeed!

Parameters

[in]	lock	pointer to rw-lock
[in]	pass	pass value; != 0, if the lock will be passed to another thread to unlock
[in]	location	location where requested

◆ rw_lock_sx_lock_low()

bool rw_lock_sx_lock_low	(	rw_lock_t *	lock,
		ulint	pass,
		ut::Location	location
	)

Low-level function for acquiring an sx lock.

Parameters

[in]	lock	pointer to rw-lock
[in]	pass	pass value; != 0, if the lock will be passed to another thread to unlock
[in]	location	location where requested

Returns: false if did not succeed, true if success.

◆ rw_lock_validate()

bool rw_lock_validate ( const rw_lock_t * lock )

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

Returns: true

Parameters

lock	in: rw-lock

◆ rw_lock_x_lock_func()

void rw_lock_x_lock_func	(	rw_lock_t *	lock,
		ulint	pass,
		ut::Location	location
	)

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 srv_n_spin_wait_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!

Parameters

[in]	lock	pointer to rw-lock
[in]	pass	pass value; != 0, if the lock will be passed to another thread to unlock
[in]	location	location where requested

◆ rw_lock_x_lock_low()

static bool rw_lock_x_lock_low	(	rw_lock_t *	lock,
		ulint	pass,
		const char *	file_name,
		ulint	line
	)

inlinestatic

Low-level function for acquiring an exclusive lock.

Returns: false if did not succeed, true if success.

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

◆ rw_lock_x_lock_move_ownership()

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.

Parameters

lock	in: lock which was x-locked in the buffer read

◆ rw_lock_x_lock_wait()

static void rw_lock_x_lock_wait	(	rw_lock_t *	lock,
		ulint	pass,
		lint	treshold,
		const char *	file_name,
		ulint	line
	)

inlinestatic

Function for the next writer to call.

Waits for readers to exit. The caller must have already decremented lock_word by X_LOCK_DECR.

Parameters

[in]	lock	pointer to rw-lock
[in]	pass	pass value; != 0, if the lock will be passed to another thread to unlock
[in]	treshold	threshold to wait for
[in]	file_name	file name where lock requested
[in]	line	line where requested

◆ rw_lock_x_lock_wait_func()

static void rw_lock_x_lock_wait_func	(	rw_lock_t *	lock,
		ulint	pass,
		lint	threshold,
		const char *	file_name,
		ulint	line
	)

inlinestatic

Function for the next writer to call.

Waits for readers to exit. The caller must have already decremented lock_word by X_LOCK_DECR.

Parameters

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

Variable Documentation

◆ rw_lock_list

rw_lock_list_t rw_lock_list {}

The global list of rw-locks.

◆ rw_lock_list_mutex

ib_mutex_t rw_lock_list_mutex

Typedefs

Functions

Variables

Detailed Description

Typedef Documentation

◆ Infos

Function Documentation

◆ rw_lock_add_debug_info()

◆ rw_lock_create_func()

◆ rw_lock_debug_create()

◆ rw_lock_debug_free()

◆ rw_lock_debug_print()

◆ rw_lock_free_func()

◆ rw_lock_get_debug_info()

◆ rw_lock_is_locked()

◆ rw_lock_list_print_info()

◆ rw_lock_own()

◆ rw_lock_own_flagged()

◆ rw_lock_remove_debug_info()

◆ rw_lock_s_lock_spin()

◆ rw_lock_sx_lock_func()

◆ rw_lock_sx_lock_low()

◆ rw_lock_validate()

◆ rw_lock_x_lock_func()

◆ rw_lock_x_lock_low()

◆ rw_lock_x_lock_move_ownership()

◆ rw_lock_x_lock_wait()

◆ rw_lock_x_lock_wait_func()

Variable Documentation

◆ rw_lock_list

◆ rw_lock_list_mutex