~drizzle-trunk/drizzle/development

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

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

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., 59 Temple

Place, Suite 330, Boston, MA 02111-1307 USA

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

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

@file lock/lock0iter.c

Lock queue iterator. Can iterate over table and record

lock queues.

Created July 16, 2007 Vasil Dimov

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

#define LOCK_MODULE_IMPLEMENTATION

#include "univ.i"

#include "lock0iter.h"

#include "lock0lock.h"

#include "lock0priv.h"

#include "ut0dbg.h"

#include "ut0lst.h"

#ifdef UNIV_DEBUG

# include "srv0srv.h" /* kernel_mutex */

#endif /* UNIV_DEBUG */

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

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 */

{

	ut_ad(mutex_own(&kernel_mutex));

	iter->current_lock = lock;

	if (bit_no != ULINT_UNDEFINED) {

		iter->bit_no = bit_no;

	} else {

		switch (lock_get_type_low(lock)) {

		case LOCK_TABLE:

			iter->bit_no = ULINT_UNDEFINED;

			break;

		case LOCK_REC:

			iter->bit_no = lock_rec_find_set_bit(lock);

			ut_a(iter->bit_no != ULINT_UNDEFINED);

			break;

		default:

			ut_error;

		}

	}

}

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

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 */

UNIV_INTERN

const lock_t*

lock_queue_iterator_get_prev(

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

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

{

	const lock_t*	prev_lock;

	ut_ad(mutex_own(&kernel_mutex));

	switch (lock_get_type_low(iter->current_lock)) {

	case LOCK_REC:

		prev_lock = lock_rec_get_prev(

			iter->current_lock, iter->bit_no);

		break;

	case LOCK_TABLE:

		prev_lock = UT_LIST_GET_PREV(

			un_member.tab_lock.locks, iter->current_lock);

		break;

	default:

		ut_error;

	}

	if (prev_lock != NULL) {

		iter->current_lock = prev_lock;

	}

	return(prev_lock);

}