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

Copyright (C) 2007, 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

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

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

@file include/lock0iter.h

Lock queue iterator type and function prototypes.

Created July 16, 2007 Vasil Dimov

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

#pragma once

#ifndef lock0iter_h

#define lock0iter_h

#include "univ.i"

#include "lock0types.h"

typedef struct lock_queue_iterator_struct {

	const lock_t*	current_lock;

	/* In case this is a record lock queue (not table lock queue)

	then bit_no is the record number within the heap in which the

	record is stored. */

	ulint		bit_no;

} lock_queue_iterator_t;

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

Initialize lock queue iterator so that it starts to iterate from

"lock". bit_no specifies the record number within the heap where the

record is stored. It can be undefined (ULINT_UNDEFINED) in two cases:

1. If the lock is a table lock, thus we have a table lock queue;

2. If the lock is a record lock and it is a wait lock. In this case

   bit_no is calculated in this function by using

   lock_rec_find_set_bit(). There is exactly one bit set in the bitmap

   of a wait lock. */

UNIV_INTERN

void

lock_queue_iterator_reset(

/*======================*/

	lock_queue_iterator_t*	iter,	/*!< out: iterator */

	const lock_t*		lock,	/*!< in: lock to start from */

	ulint			bit_no);/*!< in: record number in the

					heap */

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

Gets the previous lock in the lock queue, returns NULL if there are no

more locks (i.e. the current lock is the first one). The iterator is

receded (if not-NULL is returned).

@return	previous lock or NULL */

const lock_t*

lock_queue_iterator_get_prev(

/*=========================*/

	lock_queue_iterator_t*	iter);	/*!< in/out: iterator */

#endif /* lock0iter_h */