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/*****************************************************************************
Copyright (c) 2007, 2014, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2020, 2021, MariaDB Corporation.
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 Street, Fifth Floor, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file lock/lock0iter.cc
Lock queue iterator. Can iterate over table and record
lock queues.
Created July 16, 2007 Vasil Dimov
*******************************************************/
#define LOCK_MODULE_IMPLEMENTATION
#include "dict0mem.h"
#include "lock0iter.h"
#include "lock0lock.h"
#include "lock0priv.h"
/*******************************************************************//**
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. */
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 */
{
lock_sys.assert_locked(*lock);
iter->current_lock = lock;
if (bit_no != ULINT_UNDEFINED);
else if (lock->is_table())
bit_no= ULINT_UNDEFINED;
else
{
bit_no= lock_rec_find_set_bit(lock);
ut_ad(bit_no != ULINT_UNDEFINED);
}
iter->bit_no= bit_no;
}
/*******************************************************************//**
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 */
{
lock_sys.assert_locked(*iter->current_lock);
const lock_t *prev_lock= !iter->current_lock->is_table()
? lock_rec_get_prev(iter->current_lock, iter->bit_no)
: UT_LIST_GET_PREV(un_member.tab_lock.locks, iter->current_lock);
if (prev_lock)
iter->current_lock= prev_lock;
return prev_lock;
}
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