mirror of
https://github.com/YunoHost-Apps/mediawiki_ynh.git
synced 2024-09-03 19:46:05 +02:00
1146 lines
32 KiB
PHP
1146 lines
32 KiB
PHP
<?php
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/**
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* Database load balancing.
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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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/**
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* Database load balancing object
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*
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* @todo document
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* @ingroup Database
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*/
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class LoadBalancer {
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private $mServers, $mConns, $mLoads, $mGroupLoads;
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private $mErrorConnection;
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private $mReadIndex, $mAllowLagged;
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private $mWaitForPos, $mWaitTimeout;
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private $mLaggedSlaveMode, $mLastError = 'Unknown error';
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private $mParentInfo, $mLagTimes;
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private $mLoadMonitorClass, $mLoadMonitor;
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/**
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* @param array $params with keys:
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* servers Required. Array of server info structures.
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* masterWaitTimeout Replication lag wait timeout
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* loadMonitor Name of a class used to fetch server lag and load.
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* @throws MWException
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*/
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function __construct( $params ) {
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if ( !isset( $params['servers'] ) ) {
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throw new MWException( __CLASS__ . ': missing servers parameter' );
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}
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$this->mServers = $params['servers'];
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if ( isset( $params['waitTimeout'] ) ) {
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$this->mWaitTimeout = $params['waitTimeout'];
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} else {
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$this->mWaitTimeout = 10;
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}
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$this->mReadIndex = -1;
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$this->mWriteIndex = -1;
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$this->mConns = array(
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'local' => array(),
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'foreignUsed' => array(),
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'foreignFree' => array() );
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$this->mLoads = array();
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$this->mWaitForPos = false;
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$this->mLaggedSlaveMode = false;
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$this->mErrorConnection = false;
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$this->mAllowLagged = false;
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if ( isset( $params['loadMonitor'] ) ) {
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$this->mLoadMonitorClass = $params['loadMonitor'];
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} else {
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$master = reset( $params['servers'] );
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if ( isset( $master['type'] ) && $master['type'] === 'mysql' ) {
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$this->mLoadMonitorClass = 'LoadMonitor_MySQL';
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} else {
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$this->mLoadMonitorClass = 'LoadMonitor_Null';
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}
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}
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foreach ( $params['servers'] as $i => $server ) {
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$this->mLoads[$i] = $server['load'];
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if ( isset( $server['groupLoads'] ) ) {
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foreach ( $server['groupLoads'] as $group => $ratio ) {
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if ( !isset( $this->mGroupLoads[$group] ) ) {
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$this->mGroupLoads[$group] = array();
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}
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$this->mGroupLoads[$group][$i] = $ratio;
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}
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}
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}
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}
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/**
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* Get a LoadMonitor instance
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*
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* @return LoadMonitor
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*/
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function getLoadMonitor() {
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if ( !isset( $this->mLoadMonitor ) ) {
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$class = $this->mLoadMonitorClass;
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$this->mLoadMonitor = new $class( $this );
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}
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return $this->mLoadMonitor;
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}
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/**
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* Get or set arbitrary data used by the parent object, usually an LBFactory
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* @param $x
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* @return Mixed
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*/
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function parentInfo( $x = null ) {
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return wfSetVar( $this->mParentInfo, $x );
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}
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/**
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* Given an array of non-normalised probabilities, this function will select
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* an element and return the appropriate key
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*
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* @deprecated since 1.21, use ArrayUtils::pickRandom()
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*
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* @param $weights array
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*
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* @return bool|int|string
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*/
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function pickRandom( $weights ) {
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return ArrayUtils::pickRandom( $weights );
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}
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/**
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* @param $loads array
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* @param $wiki bool
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* @return bool|int|string
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*/
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function getRandomNonLagged( $loads, $wiki = false ) {
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# Unset excessively lagged servers
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$lags = $this->getLagTimes( $wiki );
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foreach ( $lags as $i => $lag ) {
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if ( $i != 0 ) {
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if ( $lag === false ) {
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wfDebugLog( 'replication', "Server #$i is not replicating\n" );
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unset( $loads[$i] );
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} elseif ( isset( $this->mServers[$i]['max lag'] ) && $lag > $this->mServers[$i]['max lag'] ) {
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wfDebugLog( 'replication', "Server #$i is excessively lagged ($lag seconds)\n" );
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unset( $loads[$i] );
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}
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}
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}
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# Find out if all the slaves with non-zero load are lagged
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$sum = 0;
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foreach ( $loads as $load ) {
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$sum += $load;
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}
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if ( $sum == 0 ) {
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# No appropriate DB servers except maybe the master and some slaves with zero load
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# Do NOT use the master
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# Instead, this function will return false, triggering read-only mode,
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# and a lagged slave will be used instead.
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return false;
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}
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if ( count( $loads ) == 0 ) {
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return false;
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}
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#wfDebugLog( 'connect', var_export( $loads, true ) );
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# Return a random representative of the remainder
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return ArrayUtils::pickRandom( $loads );
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}
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/**
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* Get the index of the reader connection, which may be a slave
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* This takes into account load ratios and lag times. It should
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* always return a consistent index during a given invocation
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*
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* Side effect: opens connections to databases
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* @param $group bool
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* @param $wiki bool
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* @throws MWException
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* @return bool|int|string
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*/
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function getReaderIndex( $group = false, $wiki = false ) {
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global $wgReadOnly, $wgDBClusterTimeout, $wgDBAvgStatusPoll, $wgDBtype;
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# @todo FIXME: For now, only go through all this for mysql databases
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if ( $wgDBtype != 'mysql' ) {
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return $this->getWriterIndex();
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}
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if ( count( $this->mServers ) == 1 ) {
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# Skip the load balancing if there's only one server
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return 0;
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} elseif ( $group === false and $this->mReadIndex >= 0 ) {
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# Shortcut if generic reader exists already
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return $this->mReadIndex;
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}
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wfProfileIn( __METHOD__ );
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$totalElapsed = 0;
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# convert from seconds to microseconds
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$timeout = $wgDBClusterTimeout * 1e6;
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# Find the relevant load array
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if ( $group !== false ) {
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if ( isset( $this->mGroupLoads[$group] ) ) {
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$nonErrorLoads = $this->mGroupLoads[$group];
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} else {
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# No loads for this group, return false and the caller can use some other group
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wfDebug( __METHOD__ . ": no loads for group $group\n" );
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wfProfileOut( __METHOD__ );
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return false;
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}
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} else {
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$nonErrorLoads = $this->mLoads;
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}
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if ( !$nonErrorLoads ) {
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wfProfileOut( __METHOD__ );
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throw new MWException( "Empty server array given to LoadBalancer" );
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}
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# Scale the configured load ratios according to the dynamic load (if the load monitor supports it)
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$this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $group, $wiki );
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$laggedSlaveMode = false;
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# First try quickly looking through the available servers for a server that
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# meets our criteria
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do {
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$totalThreadsConnected = 0;
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$overloadedServers = 0;
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$currentLoads = $nonErrorLoads;
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while ( count( $currentLoads ) ) {
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if ( $wgReadOnly || $this->mAllowLagged || $laggedSlaveMode ) {
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$i = ArrayUtils::pickRandom( $currentLoads );
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} else {
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$i = $this->getRandomNonLagged( $currentLoads, $wiki );
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if ( $i === false && count( $currentLoads ) != 0 ) {
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# All slaves lagged. Switch to read-only mode
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wfDebugLog( 'replication', "All slaves lagged. Switch to read-only mode\n" );
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$wgReadOnly = 'The database has been automatically locked ' .
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'while the slave database servers catch up to the master';
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$i = ArrayUtils::pickRandom( $currentLoads );
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$laggedSlaveMode = true;
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}
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}
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if ( $i === false ) {
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# pickRandom() returned false
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# This is permanent and means the configuration or the load monitor
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# wants us to return false.
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wfDebugLog( 'connect', __METHOD__ . ": pickRandom() returned false\n" );
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wfProfileOut( __METHOD__ );
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return false;
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}
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wfDebugLog( 'connect', __METHOD__ . ": Using reader #$i: {$this->mServers[$i]['host']}...\n" );
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$conn = $this->openConnection( $i, $wiki );
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if ( !$conn ) {
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wfDebugLog( 'connect', __METHOD__ . ": Failed connecting to $i/$wiki\n" );
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unset( $nonErrorLoads[$i] );
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unset( $currentLoads[$i] );
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continue;
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}
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// Perform post-connection backoff
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$threshold = isset( $this->mServers[$i]['max threads'] )
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? $this->mServers[$i]['max threads'] : false;
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$backoff = $this->getLoadMonitor()->postConnectionBackoff( $conn, $threshold );
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// Decrement reference counter, we are finished with this connection.
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// It will be incremented for the caller later.
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if ( $wiki !== false ) {
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$this->reuseConnection( $conn );
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}
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if ( $backoff ) {
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# Post-connection overload, don't use this server for now
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$totalThreadsConnected += $backoff;
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$overloadedServers++;
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unset( $currentLoads[$i] );
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} else {
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# Return this server
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break 2;
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}
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}
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# No server found yet
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$i = false;
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# If all servers were down, quit now
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if ( !count( $nonErrorLoads ) ) {
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wfDebugLog( 'connect', "All servers down\n" );
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break;
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}
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# Some servers must have been overloaded
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if ( $overloadedServers == 0 ) {
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throw new MWException( __METHOD__ . ": unexpectedly found no overloaded servers" );
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}
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# Back off for a while
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# Scale the sleep time by the number of connected threads, to produce a
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# roughly constant global poll rate
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$avgThreads = $totalThreadsConnected / $overloadedServers;
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$totalElapsed += $this->sleep( $wgDBAvgStatusPoll * $avgThreads );
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} while ( $totalElapsed < $timeout );
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if ( $totalElapsed >= $timeout ) {
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wfDebugLog( 'connect', "All servers busy\n" );
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$this->mErrorConnection = false;
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$this->mLastError = 'All servers busy';
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}
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if ( $i !== false ) {
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# Slave connection successful
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# Wait for the session master pos for a short time
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if ( $this->mWaitForPos && $i > 0 ) {
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if ( !$this->doWait( $i ) ) {
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$this->mServers[$i]['slave pos'] = $conn->getSlavePos();
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}
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}
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if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $i !== false ) {
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$this->mReadIndex = $i;
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}
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}
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wfProfileOut( __METHOD__ );
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return $i;
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}
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/**
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* Wait for a specified number of microseconds, and return the period waited
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* @param $t int
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* @return int
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*/
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function sleep( $t ) {
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wfProfileIn( __METHOD__ );
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wfDebug( __METHOD__ . ": waiting $t us\n" );
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usleep( $t );
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wfProfileOut( __METHOD__ );
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return $t;
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}
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/**
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* Set the master wait position
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* If a DB_SLAVE connection has been opened already, waits
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* Otherwise sets a variable telling it to wait if such a connection is opened
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* @param $pos DBMasterPos
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*/
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public function waitFor( $pos ) {
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wfProfileIn( __METHOD__ );
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$this->mWaitForPos = $pos;
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$i = $this->mReadIndex;
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if ( $i > 0 ) {
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if ( !$this->doWait( $i ) ) {
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$this->mServers[$i]['slave pos'] = $this->getAnyOpenConnection( $i )->getSlavePos();
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$this->mLaggedSlaveMode = true;
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}
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}
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wfProfileOut( __METHOD__ );
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}
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/**
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* Set the master wait position and wait for ALL slaves to catch up to it
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* @param $pos DBMasterPos
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*/
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public function waitForAll( $pos ) {
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wfProfileIn( __METHOD__ );
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$this->mWaitForPos = $pos;
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for ( $i = 1; $i < count( $this->mServers ); $i++ ) {
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$this->doWait( $i, true );
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}
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wfProfileOut( __METHOD__ );
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}
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/**
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* Get any open connection to a given server index, local or foreign
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* Returns false if there is no connection open
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*
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* @param $i int
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* @return DatabaseBase|bool False on failure
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*/
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function getAnyOpenConnection( $i ) {
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foreach ( $this->mConns as $conns ) {
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if ( !empty( $conns[$i] ) ) {
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return reset( $conns[$i] );
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}
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}
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return false;
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}
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/**
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* Wait for a given slave to catch up to the master pos stored in $this
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* @param $index
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* @param $open bool
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* @return bool
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*/
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protected function doWait( $index, $open = false ) {
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# Find a connection to wait on
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$conn = $this->getAnyOpenConnection( $index );
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if ( !$conn ) {
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if ( !$open ) {
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wfDebug( __METHOD__ . ": no connection open\n" );
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return false;
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} else {
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$conn = $this->openConnection( $index, '' );
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if ( !$conn ) {
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wfDebug( __METHOD__ . ": failed to open connection\n" );
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return false;
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}
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}
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}
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wfDebug( __METHOD__ . ": Waiting for slave #$index to catch up...\n" );
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$result = $conn->masterPosWait( $this->mWaitForPos, $this->mWaitTimeout );
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if ( $result == -1 || is_null( $result ) ) {
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# Timed out waiting for slave, use master instead
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wfDebug( __METHOD__ . ": Timed out waiting for slave #$index pos {$this->mWaitForPos}\n" );
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return false;
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} else {
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wfDebug( __METHOD__ . ": Done\n" );
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return true;
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}
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}
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/**
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* Get a connection by index
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* This is the main entry point for this class.
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*
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* @param $i Integer: server index
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* @param array $groups query groups
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* @param bool|string $wiki Wiki ID
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*
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* @throws MWException
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* @return DatabaseBase
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*/
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public function &getConnection( $i, $groups = array(), $wiki = false ) {
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wfProfileIn( __METHOD__ );
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if ( $i == DB_LAST ) {
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wfProfileOut( __METHOD__ );
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throw new MWException( 'Attempt to call ' . __METHOD__ . ' with deprecated server index DB_LAST' );
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} elseif ( $i === null || $i === false ) {
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wfProfileOut( __METHOD__ );
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throw new MWException( 'Attempt to call ' . __METHOD__ . ' with invalid server index' );
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}
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if ( $wiki === wfWikiID() ) {
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$wiki = false;
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}
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# Query groups
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if ( $i == DB_MASTER ) {
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$i = $this->getWriterIndex();
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} elseif ( !is_array( $groups ) ) {
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$groupIndex = $this->getReaderIndex( $groups, $wiki );
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if ( $groupIndex !== false ) {
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$serverName = $this->getServerName( $groupIndex );
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wfDebug( __METHOD__ . ": using server $serverName for group $groups\n" );
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$i = $groupIndex;
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}
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} else {
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foreach ( $groups as $group ) {
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$groupIndex = $this->getReaderIndex( $group, $wiki );
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if ( $groupIndex !== false ) {
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$serverName = $this->getServerName( $groupIndex );
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wfDebug( __METHOD__ . ": using server $serverName for group $group\n" );
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$i = $groupIndex;
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break;
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}
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}
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}
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# Operation-based index
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if ( $i == DB_SLAVE ) {
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$this->mLastError = 'Unknown error'; // reset error string
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$i = $this->getReaderIndex( false, $wiki );
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# Couldn't find a working server in getReaderIndex()?
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if ( $i === false ) {
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$this->mLastError = 'No working slave server: ' . $this->mLastError;
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wfProfileOut( __METHOD__ );
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return $this->reportConnectionError();
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}
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}
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# Now we have an explicit index into the servers array
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$conn = $this->openConnection( $i, $wiki );
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if ( !$conn ) {
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wfProfileOut( __METHOD__ );
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return $this->reportConnectionError();
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}
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wfProfileOut( __METHOD__ );
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return $conn;
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}
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|
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/**
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* Mark a foreign connection as being available for reuse under a different
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* DB name or prefix. This mechanism is reference-counted, and must be called
|
|
* the same number of times as getConnection() to work.
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|
*
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* @param DatabaseBase $conn
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* @throws MWException
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*/
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public function reuseConnection( $conn ) {
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$serverIndex = $conn->getLBInfo( 'serverIndex' );
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$refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
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$dbName = $conn->getDBname();
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$prefix = $conn->tablePrefix();
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if ( strval( $prefix ) !== '' ) {
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$wiki = "$dbName-$prefix";
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} else {
|
|
$wiki = $dbName;
|
|
}
|
|
if ( $serverIndex === null || $refCount === null ) {
|
|
wfDebug( __METHOD__ . ": this connection was not opened as a foreign connection\n" );
|
|
/**
|
|
* This can happen in code like:
|
|
* foreach ( $dbs as $db ) {
|
|
* $conn = $lb->getConnection( DB_SLAVE, array(), $db );
|
|
* ...
|
|
* $lb->reuseConnection( $conn );
|
|
* }
|
|
* When a connection to the local DB is opened in this way, reuseConnection()
|
|
* should be ignored
|
|
*/
|
|
return;
|
|
}
|
|
if ( $this->mConns['foreignUsed'][$serverIndex][$wiki] !== $conn ) {
|
|
throw new MWException( __METHOD__ . ": connection not found, has the connection been freed already?" );
|
|
}
|
|
$conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
|
|
if ( $refCount <= 0 ) {
|
|
$this->mConns['foreignFree'][$serverIndex][$wiki] = $conn;
|
|
unset( $this->mConns['foreignUsed'][$serverIndex][$wiki] );
|
|
wfDebug( __METHOD__ . ": freed connection $serverIndex/$wiki\n" );
|
|
} else {
|
|
wfDebug( __METHOD__ . ": reference count for $serverIndex/$wiki reduced to $refCount\n" );
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Get a database connection handle reference
|
|
*
|
|
* The handle's methods wrap simply wrap those of a DatabaseBase handle
|
|
*
|
|
* @see LoadBalancer::getConnection() for parameter information
|
|
*
|
|
* @param integer $db
|
|
* @param mixed $groups
|
|
* @param string $wiki
|
|
* @return DBConnRef
|
|
*/
|
|
public function getConnectionRef( $db, $groups = array(), $wiki = false ) {
|
|
return new DBConnRef( $this, $this->getConnection( $db, $groups, $wiki ) );
|
|
}
|
|
|
|
/**
|
|
* Get a database connection handle reference without connecting yet
|
|
*
|
|
* The handle's methods wrap simply wrap those of a DatabaseBase handle
|
|
*
|
|
* @see LoadBalancer::getConnection() for parameter information
|
|
*
|
|
* @param integer $db
|
|
* @param mixed $groups
|
|
* @param string $wiki
|
|
* @return DBConnRef
|
|
*/
|
|
public function getLazyConnectionRef( $db, $groups = array(), $wiki = false ) {
|
|
return new DBConnRef( $this, array( $db, $groups, $wiki ) );
|
|
}
|
|
|
|
/**
|
|
* Open a connection to the server given by the specified index
|
|
* Index must be an actual index into the array.
|
|
* If the server is already open, returns it.
|
|
*
|
|
* On error, returns false, and the connection which caused the
|
|
* error will be available via $this->mErrorConnection.
|
|
*
|
|
* @param $i Integer server index
|
|
* @param string $wiki wiki ID to open
|
|
* @return DatabaseBase
|
|
*
|
|
* @access private
|
|
*/
|
|
function openConnection( $i, $wiki = false ) {
|
|
wfProfileIn( __METHOD__ );
|
|
if ( $wiki !== false ) {
|
|
$conn = $this->openForeignConnection( $i, $wiki );
|
|
wfProfileOut( __METHOD__ );
|
|
return $conn;
|
|
}
|
|
if ( isset( $this->mConns['local'][$i][0] ) ) {
|
|
$conn = $this->mConns['local'][$i][0];
|
|
} else {
|
|
$server = $this->mServers[$i];
|
|
$server['serverIndex'] = $i;
|
|
$conn = $this->reallyOpenConnection( $server, false );
|
|
if ( $conn->isOpen() ) {
|
|
wfDebug( "Connected to database $i at {$this->mServers[$i]['host']}\n" );
|
|
$this->mConns['local'][$i][0] = $conn;
|
|
} else {
|
|
wfDebug( "Failed to connect to database $i at {$this->mServers[$i]['host']}\n" );
|
|
$this->mErrorConnection = $conn;
|
|
$conn = false;
|
|
}
|
|
}
|
|
wfProfileOut( __METHOD__ );
|
|
return $conn;
|
|
}
|
|
|
|
/**
|
|
* Open a connection to a foreign DB, or return one if it is already open.
|
|
*
|
|
* Increments a reference count on the returned connection which locks the
|
|
* connection to the requested wiki. This reference count can be
|
|
* decremented by calling reuseConnection().
|
|
*
|
|
* If a connection is open to the appropriate server already, but with the wrong
|
|
* database, it will be switched to the right database and returned, as long as
|
|
* it has been freed first with reuseConnection().
|
|
*
|
|
* On error, returns false, and the connection which caused the
|
|
* error will be available via $this->mErrorConnection.
|
|
*
|
|
* @param $i Integer: server index
|
|
* @param string $wiki wiki ID to open
|
|
* @return DatabaseBase
|
|
*/
|
|
function openForeignConnection( $i, $wiki ) {
|
|
wfProfileIn( __METHOD__ );
|
|
list( $dbName, $prefix ) = wfSplitWikiID( $wiki );
|
|
if ( isset( $this->mConns['foreignUsed'][$i][$wiki] ) ) {
|
|
// Reuse an already-used connection
|
|
$conn = $this->mConns['foreignUsed'][$i][$wiki];
|
|
wfDebug( __METHOD__ . ": reusing connection $i/$wiki\n" );
|
|
} elseif ( isset( $this->mConns['foreignFree'][$i][$wiki] ) ) {
|
|
// Reuse a free connection for the same wiki
|
|
$conn = $this->mConns['foreignFree'][$i][$wiki];
|
|
unset( $this->mConns['foreignFree'][$i][$wiki] );
|
|
$this->mConns['foreignUsed'][$i][$wiki] = $conn;
|
|
wfDebug( __METHOD__ . ": reusing free connection $i/$wiki\n" );
|
|
} elseif ( !empty( $this->mConns['foreignFree'][$i] ) ) {
|
|
// Reuse a connection from another wiki
|
|
$conn = reset( $this->mConns['foreignFree'][$i] );
|
|
$oldWiki = key( $this->mConns['foreignFree'][$i] );
|
|
|
|
if ( !$conn->selectDB( $dbName ) ) {
|
|
$this->mLastError = "Error selecting database $dbName on server " .
|
|
$conn->getServer() . " from client host " . wfHostname() . "\n";
|
|
$this->mErrorConnection = $conn;
|
|
$conn = false;
|
|
} else {
|
|
$conn->tablePrefix( $prefix );
|
|
unset( $this->mConns['foreignFree'][$i][$oldWiki] );
|
|
$this->mConns['foreignUsed'][$i][$wiki] = $conn;
|
|
wfDebug( __METHOD__ . ": reusing free connection from $oldWiki for $wiki\n" );
|
|
}
|
|
} else {
|
|
// Open a new connection
|
|
$server = $this->mServers[$i];
|
|
$server['serverIndex'] = $i;
|
|
$server['foreignPoolRefCount'] = 0;
|
|
$server['foreign'] = true;
|
|
$conn = $this->reallyOpenConnection( $server, $dbName );
|
|
if ( !$conn->isOpen() ) {
|
|
wfDebug( __METHOD__ . ": error opening connection for $i/$wiki\n" );
|
|
$this->mErrorConnection = $conn;
|
|
$conn = false;
|
|
} else {
|
|
$conn->tablePrefix( $prefix );
|
|
$this->mConns['foreignUsed'][$i][$wiki] = $conn;
|
|
wfDebug( __METHOD__ . ": opened new connection for $i/$wiki\n" );
|
|
}
|
|
}
|
|
|
|
// Increment reference count
|
|
if ( $conn ) {
|
|
$refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
|
|
$conn->setLBInfo( 'foreignPoolRefCount', $refCount + 1 );
|
|
}
|
|
wfProfileOut( __METHOD__ );
|
|
return $conn;
|
|
}
|
|
|
|
/**
|
|
* Test if the specified index represents an open connection
|
|
*
|
|
* @param $index Integer: server index
|
|
* @access private
|
|
* @return bool
|
|
*/
|
|
function isOpen( $index ) {
|
|
if ( !is_integer( $index ) ) {
|
|
return false;
|
|
}
|
|
return (bool)$this->getAnyOpenConnection( $index );
|
|
}
|
|
|
|
/**
|
|
* Really opens a connection. Uncached.
|
|
* Returns a Database object whether or not the connection was successful.
|
|
* @access private
|
|
*
|
|
* @param $server
|
|
* @param $dbNameOverride bool
|
|
* @throws MWException
|
|
* @return DatabaseBase
|
|
*/
|
|
function reallyOpenConnection( $server, $dbNameOverride = false ) {
|
|
if ( !is_array( $server ) ) {
|
|
throw new MWException( 'You must update your load-balancing configuration. ' .
|
|
'See DefaultSettings.php entry for $wgDBservers.' );
|
|
}
|
|
|
|
if ( $dbNameOverride !== false ) {
|
|
$server['dbname'] = $dbNameOverride;
|
|
}
|
|
|
|
# Create object
|
|
try {
|
|
$db = DatabaseBase::factory( $server['type'], $server );
|
|
} catch ( DBConnectionError $e ) {
|
|
// FIXME: This is probably the ugliest thing I have ever done to
|
|
// PHP. I'm half-expecting it to segfault, just out of disgust. -- TS
|
|
$db = $e->db;
|
|
}
|
|
|
|
$db->setLBInfo( $server );
|
|
if ( isset( $server['fakeSlaveLag'] ) ) {
|
|
$db->setFakeSlaveLag( $server['fakeSlaveLag'] );
|
|
}
|
|
if ( isset( $server['fakeMaster'] ) ) {
|
|
$db->setFakeMaster( true );
|
|
}
|
|
return $db;
|
|
}
|
|
|
|
/**
|
|
* @throws DBConnectionError
|
|
* @return bool
|
|
*/
|
|
private function reportConnectionError() {
|
|
$conn = $this->mErrorConnection; // The connection which caused the error
|
|
|
|
if ( !is_object( $conn ) ) {
|
|
// No last connection, probably due to all servers being too busy
|
|
wfLogDBError( "LB failure with no last connection. Connection error: {$this->mLastError}\n" );
|
|
|
|
// If all servers were busy, mLastError will contain something sensible
|
|
throw new DBConnectionError( null, $this->mLastError );
|
|
} else {
|
|
$server = $conn->getProperty( 'mServer' );
|
|
wfLogDBError( "Connection error: {$this->mLastError} ({$server})\n" );
|
|
$conn->reportConnectionError( "{$this->mLastError} ({$server})" ); // throws DBConnectionError
|
|
}
|
|
return false; /* not reached */
|
|
}
|
|
|
|
/**
|
|
* @return int
|
|
*/
|
|
function getWriterIndex() {
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Returns true if the specified index is a valid server index
|
|
*
|
|
* @param $i
|
|
* @return bool
|
|
*/
|
|
function haveIndex( $i ) {
|
|
return array_key_exists( $i, $this->mServers );
|
|
}
|
|
|
|
/**
|
|
* Returns true if the specified index is valid and has non-zero load
|
|
*
|
|
* @param $i
|
|
* @return bool
|
|
*/
|
|
function isNonZeroLoad( $i ) {
|
|
return array_key_exists( $i, $this->mServers ) && $this->mLoads[$i] != 0;
|
|
}
|
|
|
|
/**
|
|
* Get the number of defined servers (not the number of open connections)
|
|
*
|
|
* @return int
|
|
*/
|
|
function getServerCount() {
|
|
return count( $this->mServers );
|
|
}
|
|
|
|
/**
|
|
* Get the host name or IP address of the server with the specified index
|
|
* Prefer a readable name if available.
|
|
* @param $i
|
|
* @return string
|
|
*/
|
|
function getServerName( $i ) {
|
|
if ( isset( $this->mServers[$i]['hostName'] ) ) {
|
|
return $this->mServers[$i]['hostName'];
|
|
} elseif ( isset( $this->mServers[$i]['host'] ) ) {
|
|
return $this->mServers[$i]['host'];
|
|
} else {
|
|
return '';
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Return the server info structure for a given index, or false if the index is invalid.
|
|
* @param $i
|
|
* @return bool
|
|
*/
|
|
function getServerInfo( $i ) {
|
|
if ( isset( $this->mServers[$i] ) ) {
|
|
return $this->mServers[$i];
|
|
} else {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Sets the server info structure for the given index. Entry at index $i is created if it doesn't exist
|
|
* @param $i
|
|
* @param $serverInfo
|
|
*/
|
|
function setServerInfo( $i, $serverInfo ) {
|
|
$this->mServers[$i] = $serverInfo;
|
|
}
|
|
|
|
/**
|
|
* Get the current master position for chronology control purposes
|
|
* @return mixed
|
|
*/
|
|
function getMasterPos() {
|
|
# If this entire request was served from a slave without opening a connection to the
|
|
# master (however unlikely that may be), then we can fetch the position from the slave.
|
|
$masterConn = $this->getAnyOpenConnection( 0 );
|
|
if ( !$masterConn ) {
|
|
for ( $i = 1; $i < count( $this->mServers ); $i++ ) {
|
|
$conn = $this->getAnyOpenConnection( $i );
|
|
if ( $conn ) {
|
|
wfDebug( "Master pos fetched from slave\n" );
|
|
return $conn->getSlavePos();
|
|
}
|
|
}
|
|
} else {
|
|
wfDebug( "Master pos fetched from master\n" );
|
|
return $masterConn->getMasterPos();
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Close all open connections
|
|
*/
|
|
function closeAll() {
|
|
foreach ( $this->mConns as $conns2 ) {
|
|
foreach ( $conns2 as $conns3 ) {
|
|
foreach ( $conns3 as $conn ) {
|
|
$conn->close();
|
|
}
|
|
}
|
|
}
|
|
$this->mConns = array(
|
|
'local' => array(),
|
|
'foreignFree' => array(),
|
|
'foreignUsed' => array(),
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Deprecated function, typo in function name
|
|
*
|
|
* @deprecated in 1.18
|
|
* @param $conn
|
|
*/
|
|
function closeConnecton( $conn ) {
|
|
wfDeprecated( __METHOD__, '1.18' );
|
|
$this->closeConnection( $conn );
|
|
}
|
|
|
|
/**
|
|
* Close a connection
|
|
* Using this function makes sure the LoadBalancer knows the connection is closed.
|
|
* If you use $conn->close() directly, the load balancer won't update its state.
|
|
* @param $conn DatabaseBase
|
|
*/
|
|
function closeConnection( $conn ) {
|
|
$done = false;
|
|
foreach ( $this->mConns as $i1 => $conns2 ) {
|
|
foreach ( $conns2 as $i2 => $conns3 ) {
|
|
foreach ( $conns3 as $i3 => $candidateConn ) {
|
|
if ( $conn === $candidateConn ) {
|
|
$conn->close();
|
|
unset( $this->mConns[$i1][$i2][$i3] );
|
|
$done = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if ( !$done ) {
|
|
$conn->close();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Commit transactions on all open connections
|
|
*/
|
|
function commitAll() {
|
|
foreach ( $this->mConns as $conns2 ) {
|
|
foreach ( $conns2 as $conns3 ) {
|
|
foreach ( $conns3 as $conn ) {
|
|
if ( $conn->trxLevel() ) {
|
|
$conn->commit( __METHOD__, 'flush' );
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Issue COMMIT only on master, only if queries were done on connection
|
|
*/
|
|
function commitMasterChanges() {
|
|
// Always 0, but who knows.. :)
|
|
$masterIndex = $this->getWriterIndex();
|
|
foreach ( $this->mConns as $conns2 ) {
|
|
if ( empty( $conns2[$masterIndex] ) ) {
|
|
continue;
|
|
}
|
|
foreach ( $conns2[$masterIndex] as $conn ) {
|
|
if ( $conn->trxLevel() && $conn->writesOrCallbacksPending() ) {
|
|
$conn->commit( __METHOD__, 'flush' );
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @param $value null
|
|
* @return Mixed
|
|
*/
|
|
function waitTimeout( $value = null ) {
|
|
return wfSetVar( $this->mWaitTimeout, $value );
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
function getLaggedSlaveMode() {
|
|
return $this->mLaggedSlaveMode;
|
|
}
|
|
|
|
/**
|
|
* Disables/enables lag checks
|
|
* @param $mode null
|
|
* @return bool
|
|
*/
|
|
function allowLagged( $mode = null ) {
|
|
if ( $mode === null ) {
|
|
return $this->mAllowLagged;
|
|
}
|
|
$this->mAllowLagged = $mode;
|
|
return $this->mAllowLagged;
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
function pingAll() {
|
|
$success = true;
|
|
foreach ( $this->mConns as $conns2 ) {
|
|
foreach ( $conns2 as $conns3 ) {
|
|
foreach ( $conns3 as $conn ) {
|
|
if ( !$conn->ping() ) {
|
|
$success = false;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return $success;
|
|
}
|
|
|
|
/**
|
|
* Call a function with each open connection object
|
|
* @param $callback
|
|
* @param array $params
|
|
*/
|
|
function forEachOpenConnection( $callback, $params = array() ) {
|
|
foreach ( $this->mConns as $conns2 ) {
|
|
foreach ( $conns2 as $conns3 ) {
|
|
foreach ( $conns3 as $conn ) {
|
|
$mergedParams = array_merge( array( $conn ), $params );
|
|
call_user_func_array( $callback, $mergedParams );
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Get the hostname and lag time of the most-lagged slave.
|
|
* This is useful for maintenance scripts that need to throttle their updates.
|
|
* May attempt to open connections to slaves on the default DB. If there is
|
|
* no lag, the maximum lag will be reported as -1.
|
|
*
|
|
* @param string $wiki Wiki ID, or false for the default database
|
|
*
|
|
* @return array ( host, max lag, index of max lagged host )
|
|
*/
|
|
function getMaxLag( $wiki = false ) {
|
|
$maxLag = -1;
|
|
$host = '';
|
|
$maxIndex = 0;
|
|
if ( $this->getServerCount() > 1 ) { // no replication = no lag
|
|
foreach ( $this->mServers as $i => $conn ) {
|
|
$conn = false;
|
|
if ( $wiki === false ) {
|
|
$conn = $this->getAnyOpenConnection( $i );
|
|
}
|
|
if ( !$conn ) {
|
|
$conn = $this->openConnection( $i, $wiki );
|
|
}
|
|
if ( !$conn ) {
|
|
continue;
|
|
}
|
|
$lag = $conn->getLag();
|
|
if ( $lag > $maxLag ) {
|
|
$maxLag = $lag;
|
|
$host = $this->mServers[$i]['host'];
|
|
$maxIndex = $i;
|
|
}
|
|
}
|
|
}
|
|
return array( $host, $maxLag, $maxIndex );
|
|
}
|
|
|
|
/**
|
|
* Get lag time for each server
|
|
* Results are cached for a short time in memcached, and indefinitely in the process cache
|
|
*
|
|
* @param $wiki
|
|
*
|
|
* @return array
|
|
*/
|
|
function getLagTimes( $wiki = false ) {
|
|
# Try process cache
|
|
if ( isset( $this->mLagTimes ) ) {
|
|
return $this->mLagTimes;
|
|
}
|
|
if ( $this->getServerCount() == 1 ) {
|
|
# No replication
|
|
$this->mLagTimes = array( 0 => 0 );
|
|
} else {
|
|
# Send the request to the load monitor
|
|
$this->mLagTimes = $this->getLoadMonitor()->getLagTimes(
|
|
array_keys( $this->mServers ), $wiki );
|
|
}
|
|
return $this->mLagTimes;
|
|
}
|
|
|
|
/**
|
|
* Get the lag in seconds for a given connection, or zero if this load
|
|
* balancer does not have replication enabled.
|
|
*
|
|
* This should be used in preference to Database::getLag() in cases where
|
|
* replication may not be in use, since there is no way to determine if
|
|
* replication is in use at the connection level without running
|
|
* potentially restricted queries such as SHOW SLAVE STATUS. Using this
|
|
* function instead of Database::getLag() avoids a fatal error in this
|
|
* case on many installations.
|
|
*
|
|
* @param $conn DatabaseBase
|
|
*
|
|
* @return int
|
|
*/
|
|
function safeGetLag( $conn ) {
|
|
if ( $this->getServerCount() == 1 ) {
|
|
return 0;
|
|
} else {
|
|
return $conn->getLag();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Clear the cache for getLagTimes
|
|
*/
|
|
function clearLagTimeCache() {
|
|
$this->mLagTimes = null;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Helper class to handle automatically marking connectons as reusable (via RAII pattern)
|
|
* as well handling deferring the actual network connection until the handle is used
|
|
*
|
|
* @ingroup Database
|
|
* @since 1.22
|
|
*/
|
|
class DBConnRef implements IDatabase {
|
|
/** @var LoadBalancer */
|
|
protected $lb;
|
|
/** @var DatabaseBase|null */
|
|
protected $conn;
|
|
/** @var Array|null */
|
|
protected $params;
|
|
|
|
/**
|
|
* @param $lb LoadBalancer
|
|
* @param $conn DatabaseBase|array Connection or (server index, group, wiki ID) array
|
|
*/
|
|
public function __construct( LoadBalancer $lb, $conn ) {
|
|
$this->lb = $lb;
|
|
if ( $conn instanceof DatabaseBase ) {
|
|
$this->conn = $conn;
|
|
} else {
|
|
$this->params = $conn;
|
|
}
|
|
}
|
|
|
|
public function __call( $name, $arguments ) {
|
|
if ( $this->conn === null ) {
|
|
list( $db, $groups, $wiki ) = $this->params;
|
|
$this->conn = $this->lb->getConnection( $db, $groups, $wiki );
|
|
}
|
|
return call_user_func_array( array( $this->conn, $name ), $arguments );
|
|
}
|
|
|
|
function __destruct() {
|
|
if ( $this->conn !== null ) {
|
|
$this->lb->reuseConnection( $this->conn );
|
|
}
|
|
}
|
|
}
|