98 lines
2.4 KiB
PHP
98 lines
2.4 KiB
PHP
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<?php
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namespace Wikimedia\Rdbms;
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use Database;
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use DBConnRef;
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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 slave databases. It also manages state that indicates whether
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* the slave databases are possibly outdated after a write operation, and thus the master database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 slave
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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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* @license GPL-2.0+
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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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