The wait array used in synchronization primitives. More...

#include "univ.i"
#include "sync0arr.ic"

Functions
static sync_array_t *	sync_array_get_and_reserve_cell (void object, ulint type, ut::Location location, sync_cell_t *cell)
	Get an instance of the sync wait array and reserve a wait array cell in the instance for waiting for an object. More...

sync_cell_t *	sync_array_reserve_cell (sync_array_t arr, void object, ulint type, ut::Location location)
	Reserves a wait array cell for waiting for an object. More...

void	sync_array_wait_event (sync_array_t arr, sync_cell_t &cell)
	This function should be called when a thread starts to wait on a wait array cell. More...

void	sync_array_free_cell (sync_array_t arr, sync_cell_t &cell)
	Frees the cell. More...

void	sync_array_object_signalled ()
	Note that one of the wait objects was signalled. More...

void	sync_arr_wake_threads_if_sema_free ()
	If the wakeup algorithm does not work perfectly at semaphore releases, this function will do the waking (see the comment in mutex_exit). More...

bool	sync_array_print_long_waits (std::thread::id waiter, const void *sema)
	Prints warnings of long semaphore waits to stderr. More...

void	sync_array_detect_deadlock ()

void	sync_array_print (FILE *file)
	Prints info of the wait array. More...

void	sync_array_init (ulint n_threads)
	Create the primary system wait array(s), they are protected by an OS mutex. More...

void	sync_array_close ()
	Close sync array wait sub-system. More...

static sync_array_t *	sync_array_get ()
	Get an instance of the sync wait array. More...

Detailed Description

The wait array used in synchronization primitives.

Created 9/5/1995 Heikki Tuuri

Function Documentation

◆ sync_arr_wake_threads_if_sema_free()

void sync_arr_wake_threads_if_sema_free ( void )

If the wakeup algorithm does not work perfectly at semaphore releases, this function will do the waking (see the comment in mutex_exit).

This function should be called about every 1 second in the server.

Note that there's a race condition between this thread and mutex_exit changing the lock_word and calling signal_object, so sometimes this finds threads to wake up even when nothing has gone wrong.

◆ sync_array_close()

void sync_array_close ( )

Close sync array wait sub-system.

◆ sync_array_detect_deadlock()

void sync_array_detect_deadlock ( )

◆ sync_array_free_cell()

void sync_array_free_cell	(	sync_array_t *	arr,
		sync_cell_t *&	cell
	)

Frees the cell.

NOTE! sync_array_wait_event frees the cell automatically! in: the reserved cell

NOTE! sync_array_wait_event frees the cell automatically!

Parameters

arr	in: wait array
cell	in/out: the cell in the array

◆ sync_array_get()

static sync_array_t * sync_array_get ( )

inlinestatic

Get an instance of the sync wait array.

◆ sync_array_get_and_reserve_cell()

static sync_array_t * sync_array_get_and_reserve_cell	(	void *	object,
		ulint	type,
		ut::Location	location,
		sync_cell_t **	cell
	)

inlinestatic

Get an instance of the sync wait array and reserve a wait array cell in the instance for waiting for an object.

The event of the cell is reset to nonsignalled state. If reserving cell of the instance fails, try to get another new instance until we can reserve an empty cell of it.

Parameters

[in]	object	pointer to the object to wait for
[in]	type	lock request type
[in]	location	location where requested
[out]	cell	the cell reserved, never NULL

Returns: the sync array found, never NULL.

◆ sync_array_init()

void sync_array_init ( ulint n_threads )

Create the primary system wait array(s), they are protected by an OS mutex.

in: Number of slots to create

Parameters

n_threads in: Number of slots to create in all arrays

◆ sync_array_object_signalled()

void sync_array_object_signalled ( )

Note that one of the wait objects was signalled.

◆ sync_array_print()

void sync_array_print ( FILE * file )

Prints info of the wait array.

in: file where to print

Prints info of the wait array.

Parameters

file	in/out: Print to this stream

◆ sync_array_print_long_waits()

bool sync_array_print_long_waits	(	std::thread::id *	waiter,
		const void **	sema
	)

Prints warnings of long semaphore waits to stderr.

Returns: true if fatal semaphore wait threshold was exceeded out: longest-waited-for semaphore; true if fatal semaphore wait threshold was exceeded

Parameters

waiter	out: longest waiting thread
sema	out: longest-waited-for semaphore

◆ sync_array_reserve_cell()

sync_cell_t * sync_array_reserve_cell	(	sync_array_t *	arr,
		void *	object,
		ulint	type,
		ut::Location	location
	)

Reserves a wait array cell for waiting for an object.

The event of the cell is reset to nonsignalled state.

Parameters

[in]	arr	wait array
[in]	object	pointer to the object to wait for
[in]	type	lock request type
[in]	location	location where requested

Returns: sync cell to wait on

◆ sync_array_wait_event()

void sync_array_wait_event	(	sync_array_t *	arr,
		sync_cell_t *&	cell
	)

This function should be called when a thread starts to wait on a wait array cell.

In the debug version this function checks if the wait for a semaphore will result in a deadlock, in which case prints info and asserts. in: the reserved cell

In the debug version this function checks if the wait for a semaphore will result in a deadlock, in which case prints info and asserts.

Parameters

arr	in: wait array
cell	in: index of the reserved cell

Functions

Detailed Description

Function Documentation

◆ sync_arr_wake_threads_if_sema_free()

◆ sync_array_close()

◆ sync_array_detect_deadlock()

◆ sync_array_free_cell()

◆ sync_array_get()

◆ sync_array_get_and_reserve_cell()

◆ sync_array_init()

◆ sync_array_object_signalled()

◆ sync_array_print()

◆ sync_array_print_long_waits()

◆ sync_array_reserve_cell()

◆ sync_array_wait_event()