107 lines
3.5 KiB
C++
107 lines
3.5 KiB
C++
/*****************************************************************************
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Copyright (c) 2007, 2018, Oracle and/or its affiliates. All Rights Reserved.
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License, version 2.0, as published by the
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Free Software Foundation.
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This program is also distributed with certain software (including but not
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limited to OpenSSL) that is licensed under separate terms, as designated in a
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particular file or component or in included license documentation. The authors
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of MySQL hereby grant you an additional permission to link the program and
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your derivative works with the separately licensed software that they have
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included with MySQL.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
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for more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*****************************************************************************/
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/** @file lock/lock0iter.cc
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Lock queue iterator. Can iterate over table and record
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lock queues.
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Created July 16, 2007 Vasil Dimov
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*******************************************************/
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#define LOCK_MODULE_IMPLEMENTATION
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#include <stddef.h>
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#include "dict0mem.h"
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#include "lock0iter.h"
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#include "lock0lock.h"
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#include "lock0priv.h"
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#include "univ.i"
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/** Initialize lock queue iterator so that it starts to iterate from
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"lock". bit_no specifies the record number within the heap where the
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record is stored. It can be undefined (ULINT_UNDEFINED) in two cases:
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1. If the lock is a table lock, thus we have a table lock queue;
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2. If the lock is a record lock and it is a wait lock. In this case
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bit_no is calculated in this function by using
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lock_rec_find_set_bit(). There is exactly one bit set in the bitmap
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of a wait lock. */
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void lock_queue_iterator_reset(
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lock_queue_iterator_t *iter, /*!< out: iterator */
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const lock_t *lock, /*!< in: lock to start from */
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ulint bit_no) /*!< in: record number in the
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heap */
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{
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ut_ad(lock_mutex_own());
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iter->current_lock = lock;
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if (bit_no != ULINT_UNDEFINED) {
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iter->bit_no = bit_no;
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} else {
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switch (lock_get_type_low(lock)) {
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case LOCK_TABLE:
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iter->bit_no = ULINT_UNDEFINED;
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break;
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case LOCK_REC:
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iter->bit_no = lock_rec_find_set_bit(lock);
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ut_a(iter->bit_no != ULINT_UNDEFINED);
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break;
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default:
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ut_error;
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}
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}
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}
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/** Gets the previous lock in the lock queue, returns NULL if there are no
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more locks (i.e. the current lock is the first one). The iterator is
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receded (if not-NULL is returned).
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@return previous lock or NULL */
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const lock_t *lock_queue_iterator_get_prev(
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lock_queue_iterator_t *iter) /*!< in/out: iterator */
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{
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const lock_t *prev_lock;
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ut_ad(lock_mutex_own());
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switch (lock_get_type_low(iter->current_lock)) {
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case LOCK_REC:
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prev_lock = lock_rec_get_prev(iter->current_lock, iter->bit_no);
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break;
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case LOCK_TABLE:
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prev_lock = UT_LIST_GET_PREV(tab_lock.locks, iter->current_lock);
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break;
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default:
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ut_error;
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}
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if (prev_lock != NULL) {
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iter->current_lock = prev_lock;
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}
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return (prev_lock);
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}
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