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b01d8e1a33
For now, we will acquire the lock_sys.latch only in exclusive mode, that is, use it as a mutex. This is preparation for the next commit where we will introduce a less intrusive alternative, combining a shared lock_sys.latch with dict_table_t::lock_mutex or a mutex embedded in lock_sys.rec_hash, lock_sys.prdt_hash, or lock_sys.prdt_page_hash.
88 lines
3 KiB
C++
88 lines
3 KiB
C++
/*****************************************************************************
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Copyright (c) 2007, 2014, Oracle and/or its affiliates. All Rights Reserved.
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Copyright (c) 2020, 2021, MariaDB Corporation.
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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 as published by the Free Software
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Foundation; version 2 of the License.
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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 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 Street, Fifth Floor, Boston, MA 02110-1335 USA
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*****************************************************************************/
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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 "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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/*******************************************************************//**
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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
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lock_queue_iterator_reset(
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/*======================*/
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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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lock_sys.assert_locked(*lock);
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iter->current_lock = lock;
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if (bit_no != ULINT_UNDEFINED);
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else if (lock->is_table())
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bit_no= ULINT_UNDEFINED;
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else
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{
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bit_no= lock_rec_find_set_bit(lock);
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ut_ad(bit_no != ULINT_UNDEFINED);
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}
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iter->bit_no= bit_no;
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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*
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lock_queue_iterator_get_prev(
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/*=========================*/
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lock_queue_iterator_t* iter) /*!< in/out: iterator */
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{
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lock_sys.assert_locked(*iter->current_lock);
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const lock_t *prev_lock= !iter->current_lock->is_table()
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? lock_rec_get_prev(iter->current_lock, iter->bit_no)
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: UT_LIST_GET_PREV(un_member.tab_lock.locks, iter->current_lock);
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if (prev_lock)
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iter->current_lock= prev_lock;
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return prev_lock;
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}
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