bee9f4db96
Redundant given this is the project-wide license already, especially in file headers that already include the GPL license header. This and other minor fixups based on feedback from Ie0cea0ef5027c7e5. * Add @file where missing. * Move @ingroup and @deprecated from file to class doc where needed. Change-Id: I7067abb7abee1f0c238cb2536e16192e946d8daa
112 lines
3.1 KiB
PHP
112 lines
3.1 KiB
PHP
<?php
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/**
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Database
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*/
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namespace Wikimedia\Rdbms;
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/**
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* Database connection manager.
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*
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* This manages access to master and replica databases. It also manages state that indicates whether
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* the replica databases are possibly outdated after a write operation, and thus the master database
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* should be used for subsequent read operations.
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*
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* @note: Services that access overlapping sets of database tables, or interact with logically
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* related sets of data in the database, should share a SessionConsistentConnectionManager.
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* Services accessing unrelated sets of information may prefer to not share a
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* SessionConsistentConnectionManager, so they can still perform read operations against replica
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* databases after a (unrelated, per the assumption) write operation to the master database.
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* Generally, sharing a SessionConsistentConnectionManager improves consistency (by avoiding race
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* conditions due to replication lag), but can reduce performance (by directing more read
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* operations to the master database server).
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*
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* @since 1.29
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*
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* @author Daniel Kinzler
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* @author Addshore
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*/
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class SessionConsistentConnectionManager extends ConnectionManager {
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/**
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* @var bool
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*/
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private $forceWriteConnection = false;
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/**
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* Forces all future calls to getReadConnection() to return a write connection.
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* Use this before performing read operations that are critical for a future update.
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*
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* @since 1.29
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*/
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public function prepareForUpdates() {
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$this->forceWriteConnection = true;
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}
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/**
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* @since 1.29
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*
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* @param string[]|null $groups
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*
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* @return Database
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*/
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public function getReadConnection( array $groups = null ) {
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if ( $this->forceWriteConnection ) {
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return parent::getWriteConnection();
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}
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return parent::getReadConnection( $groups );
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}
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/**
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* @since 1.29
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*
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* @return Database
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*/
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public function getWriteConnection() {
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$this->prepareForUpdates();
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return parent::getWriteConnection();
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}
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/**
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* @since 1.29
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*
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* @param string[]|null $groups
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*
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* @return DBConnRef
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*/
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public function getReadConnectionRef( array $groups = null ) {
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if ( $this->forceWriteConnection ) {
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return parent::getWriteConnectionRef();
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}
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return parent::getReadConnectionRef( $groups );
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}
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/**
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* @since 1.29
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*
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* @return DBConnRef
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*/
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public function getWriteConnectionRef() {
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$this->prepareForUpdates();
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return parent::getWriteConnectionRef();
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}
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}
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