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

Copyright (c) 1995, 2009, Innobase Oy. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 
51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

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

/**************************************************//**
@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 */
typedef struct sync_cell_struct		sync_cell_t;
/** Synchronization wait array */
typedef struct sync_array_struct	sync_array_t;

/** Parameters for sync_array_create() @{ */
#define SYNC_ARRAY_OS_MUTEX	1	/*!< protected by os_mutex_t */
#define SYNC_ARRAY_MUTEX	2	/*!< protected by mutex_t */
/* @} */

/*******************************************************************//**
Creates a synchronization wait array. It is protected by a mutex
which is automatically reserved when the functions operating on it
are called.
@return	own: created wait array */
UNIV_INTERN
sync_array_t*
sync_array_create(
/*==============*/
	ulint	n_cells,	/*!< in: number of cells in the array
				to create */
	ulint	protection);	/*!< in: either SYNC_ARRAY_OS_MUTEX or
				SYNC_ARRAY_MUTEX: determines the type
				of mutex protecting the data structure */
/******************************************************************//**
Frees the resources in a wait array. */
UNIV_INTERN
void
sync_array_free(
/*============*/
	sync_array_t*	arr);	/*!< in, own: sync wait array */
/******************************************************************//**
Reserves a wait array cell for waiting for an object.
The event of the cell is reset to nonsignalled state. */
UNIV_INTERN
void
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(
/*========================*/
	sync_array_t*	arr);	/*!< in: wait array */
/**********************************************************************//**
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 */
	__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_info(
/*==================*/
	FILE*		file,	/*!< in: file where to print */
	sync_array_t*	arr);	/*!< in: wait array */


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

#endif
