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

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This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
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*****************************************************************************/

/**************************************************//**
@file include/sync0arr.h
The wait array used in synchronization primitives

Created 9/5/1995 Heikki Tuuri
*******************************************************/

#ifndef sync0arr_h
#define sync0arr_h

#include "univ.i"
#include "ut0lst.h"
#include "ut0mem.h"
#include "os0thread.h"

/** Synchronization wait array cell */
struct sync_cell_t;
/** Synchronization wait array */
struct sync_array_t;

/******************************************************************//**
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.
@return the instance found, never NULL. */
UNIV_INLINE
sync_array_t*
sync_array_get_and_reserve_cell(
/*============================*/
	void*		object,	/*!< in: pointer to the object to wait for */
	ulint		type,	/*!< in: lock request type */
	const char*	file,	/*!< in: file where requested */
	ulint		line,	/*!< in: line where requested */
	ulint*		index);	/*!< out: index of the reserved cell */
/******************************************************************//**
Reserves a wait array cell for waiting for an object.
The event of the cell is reset to nonsignalled state.
@return true if free cell is found, otherwise false */
UNIV_INTERN
bool
sync_array_reserve_cell(
/*====================*/
	sync_array_t*	arr,	/*!< in: wait array */
	void*		object, /*!< in: pointer to the object to wait for */
	ulint		type,	/*!< in: lock request type */
	const char*	file,	/*!< in: file where requested */
	ulint		line,	/*!< in: line where requested */
	ulint*		index); /*!< out: index of the reserved 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. */
UNIV_INTERN
void
sync_array_wait_event(
/*==================*/
	sync_array_t*	arr,	/*!< in: wait array */
	ulint		index);	 /*!< in: index of the reserved cell */
/******************************************************************//**
Frees the cell. NOTE! sync_array_wait_event frees the cell
automatically! */
UNIV_INTERN
void
sync_array_free_cell(
/*=================*/
	sync_array_t*	arr,	/*!< in: wait array */
	ulint		index);	/*!< in: index of the cell in array */
/**********************************************************************//**
Note that one of the wait objects was signalled. */
UNIV_INTERN
void
sync_array_object_signalled(void);
/*=============================*/

/**********************************************************************//**
If the wakeup algorithm does not work perfectly at semaphore relases,
this function will do the waking (see the comment in mutex_exit). This
function should be called about every 1 second in the server. */
UNIV_INTERN
void
sync_arr_wake_threads_if_sema_free(void);
/*====================================*/
/**********************************************************************//**
Prints warnings of long semaphore waits to stderr.
@return	TRUE if fatal semaphore wait threshold was exceeded */
UNIV_INTERN
ibool
sync_array_print_long_waits(
/*========================*/
	os_thread_id_t*	waiter,	/*!< out: longest waiting thread */
	const void**	sema)	/*!< out: longest-waited-for semaphore */
	MY_ATTRIBUTE((nonnull));
/********************************************************************//**
Validates the integrity of the wait array. Checks
that the number of reserved cells equals the count variable. */
UNIV_INTERN
void
sync_array_validate(
/*================*/
	sync_array_t*	arr);	/*!< in: sync wait array */
/**********************************************************************//**
Prints info of the wait array. */
UNIV_INTERN
void
sync_array_print(
/*=============*/
	FILE*		file);	/*!< in: file where to print */

/**********************************************************************//**
Create the primary system wait array(s), they are protected by an OS mutex */
UNIV_INTERN
void
sync_array_init(
/*============*/
	ulint		n_threads);	/*!< in: Number of slots to create */
/**********************************************************************//**
Close sync array wait sub-system. */
UNIV_INTERN
void
sync_array_close(void);
/*==================*/

/**********************************************************************//**
Get an instance of the sync wait array. */
UNIV_INTERN
sync_array_t*
sync_array_get(void);
/*================*/

#ifndef UNIV_NONINL
#include "sync0arr.ic"
#endif

#endif
