ea93933ee9
* Fixed breakage due to lag time cache, based on a hack in the WMF working copy. * Tested locally.
928 lines
26 KiB
PHP
928 lines
26 KiB
PHP
<?php
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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 */ var $mServers, $mConns, $mLoads, $mGroupLoads;
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/* private */ var $mFailFunction, $mErrorConnection;
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/* private */ var $mReadIndex, $mAllowLagged;
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/* private */ var $mWaitForPos, $mWaitTimeout;
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/* private */ var $mLaggedSlaveMode, $mLastError = 'Unknown error';
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/* private */ var $mParentInfo, $mLagTimes;
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/* private */ var $mLoadMonitorClass, $mLoadMonitor;
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/**
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* @param $params Array with keys:
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* servers Required. Array of server info structures.
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* failFunction Deprecated, use exceptions instead.
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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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*/
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function __construct( $params )
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{
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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( $params['failFunction'] ) ) {
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$this->mFailFunction = $params['failFunction'];
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} else {
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$this->mFailFunction = false;
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}
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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->mAllowLag = false;
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$this->mLoadMonitorClass = isset( $params['loadMonitor'] )
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? $params['loadMonitor'] : 'LoadMonitor_MySQL';
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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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static function newFromParams( $servers, $failFunction = false, $waitTimeout = 10 )
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{
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return new LoadBalancer( $servers, $failFunction, $waitTimeout );
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}
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/**
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* Get a LoadMonitor instance
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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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*/
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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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function pickRandom( $weights )
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{
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if ( !is_array( $weights ) || count( $weights ) == 0 ) {
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return false;
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}
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$sum = array_sum( $weights );
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if ( $sum == 0 ) {
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# No loads on any of them
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# In previous versions, this triggered an unweighted random selection,
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# but this feature has been removed as of April 2006 to allow for strict
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# separation of query groups.
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return false;
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}
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$max = mt_getrandmax();
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$rand = mt_rand(0, $max) / $max * $sum;
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$sum = 0;
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foreach ( $weights as $i => $w ) {
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$sum += $w;
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if ( $sum >= $rand ) {
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break;
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}
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}
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return $i;
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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 && isset( $this->mServers[$i]['max lag'] ) ) {
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if ( $lag === false ) {
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wfDebug( "Server #$i is not replicating\n" );
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unset( $loads[$i] );
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} elseif ( $lag > $this->mServers[$i]['max lag'] ) {
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wfDebug( "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 $this->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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*/
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function getReaderIndex( $group = false, $wiki = false ) {
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global $wgReadOnly, $wgDBClusterTimeout, $wgDBAvgStatusPoll, $wgDBtype;
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# FIXME: For now, only go through all this for mysql databases
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if ($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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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, $wiki );
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$i = false;
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$found = false;
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$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 = $this->pickRandom( $currentLoads );
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} else {
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$i = $this->getRandomNonLagged( $currentLoads, $wiki );
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if ( $i === false && count( $currentLoads ) != 0 ) {
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# All slaves lagged. Switch to read-only mode
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$wgReadOnly = wfMsgNoDBForContent( 'readonly_lag' );
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$i = $this->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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*/
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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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* Get a random server to use in a query group
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* @deprecated use getReaderIndex
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*/
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function getGroupIndex( $group ) {
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return $this->getReaderIndex( $group );
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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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*/
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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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* 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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function getAnyOpenConnection( $i ) {
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foreach ( $this->mConns as $type => $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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*/
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function doWait( $index ) {
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# Find a connection to wait on
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$conn = $this->getAnyOpenConnection( $index );
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if ( !$conn ) {
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wfDebug( __METHOD__ . ": no connection open\n" );
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return false;
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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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* @param $i Integer: server index
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* @param $groups Array: query groups
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* @param $wiki String: wiki ID
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*/
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public function &getConnection( $i, $groups = array(), $wiki = false ) {
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global $wgDBtype;
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wfProfileIn( __METHOD__ );
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if ( $i == DB_LAST ) {
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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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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 ( $i == DB_SLAVE ) {
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$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: ' . $this->mLastError;
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$this->reportConnectionError( $this->mErrorConnection );
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return false;
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}
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}
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# Now we have an explicit index into the servers array
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$conn = $this->openConnection( $i, $wiki );
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if ( !$conn ) {
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$this->reportConnectionError( $this->mErrorConnection );
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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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* 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
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* the same number of times as getConnection() to work.
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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 {
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$wiki = $dbName;
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}
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if ( $serverIndex === null || $refCount === null ) {
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wfDebug( __METHOD__.": this connection was not opened as a foreign connection\n" );
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|
/**
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|
* This can happen in code like:
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* foreach ( $dbs as $db ) {
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* $conn = $lb->getConnection( DB_SLAVE, array(), $db );
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* ...
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* $lb->reuseConnection( $conn );
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* }
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* When a connection to the local DB is opened in this way, reuseConnection()
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* should be ignored
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*/
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return;
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}
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if ( $this->mConns['foreignUsed'][$serverIndex][$wiki] !== $conn ) {
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throw new MWException( __METHOD__.": connection not found, has the connection been freed already?" );
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}
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$conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
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if ( $refCount <= 0 ) {
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$this->mConns['foreignFree'][$serverIndex][$wiki] = $conn;
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unset( $this->mConns['foreignUsed'][$serverIndex][$wiki] );
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wfDebug( __METHOD__.": freed connection $serverIndex/$wiki\n" );
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} else {
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wfDebug( __METHOD__.": reference count for $serverIndex/$wiki reduced to $refCount\n" );
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}
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}
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|
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/**
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* Open a connection to the server given by the specified index
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* Index must be an actual index into the array.
|
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* If the server is already open, returns it.
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*
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* On error, returns false, and the connection which caused the
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* error will be available via $this->mErrorConnection.
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|
*
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|
* @param $i Integer: server index
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|
* @param $wiki String: wiki ID to open
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* @return DatabaseBase
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*
|
|
* @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() ) {
|
|
$this->mConns['local'][$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 $wiki String: 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;
|
|
$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
|
|
*/
|
|
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
|
|
*/
|
|
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.' );
|
|
}
|
|
|
|
extract( $server );
|
|
if ( $dbNameOverride !== false ) {
|
|
$dbname = $dbNameOverride;
|
|
}
|
|
|
|
# Get class for this database type
|
|
$class = 'Database' . ucfirst( $type );
|
|
|
|
# Create object
|
|
wfDebug( "Connecting to $host $dbname...\n" );
|
|
$db = new $class( $host, $user, $password, $dbname, 1, $flags );
|
|
if ( $db->isOpen() ) {
|
|
wfDebug( "Connected\n" );
|
|
} else {
|
|
wfDebug( "Failed\n" );
|
|
}
|
|
$db->setLBInfo( $server );
|
|
if ( isset( $server['fakeSlaveLag'] ) ) {
|
|
$db->setFakeSlaveLag( $server['fakeSlaveLag'] );
|
|
}
|
|
if ( isset( $server['fakeMaster'] ) ) {
|
|
$db->setFakeMaster( true );
|
|
}
|
|
return $db;
|
|
}
|
|
|
|
function reportConnectionError( &$conn ) {
|
|
wfProfileIn( __METHOD__ );
|
|
|
|
if ( !is_object( $conn ) ) {
|
|
// No last connection, probably due to all servers being too busy
|
|
wfLogDBError( "LB failure with no last connection\n" );
|
|
$conn = new Database;
|
|
if ( $this->mFailFunction ) {
|
|
$conn->failFunction( $this->mFailFunction );
|
|
$conn->reportConnectionError( $this->mLastError );
|
|
} else {
|
|
// If all servers were busy, mLastError will contain something sensible
|
|
throw new DBConnectionError( $conn, $this->mLastError );
|
|
}
|
|
} else {
|
|
if ( $this->mFailFunction ) {
|
|
$conn->failFunction( $this->mFailFunction );
|
|
} else {
|
|
$conn->failFunction( false );
|
|
}
|
|
$server = $conn->getProperty( 'mServer' );
|
|
wfLogDBError( "Connection error: {$this->mLastError} ({$server})\n" );
|
|
$conn->reportConnectionError( "{$this->mLastError} ({$server})" );
|
|
}
|
|
wfProfileOut( __METHOD__ );
|
|
}
|
|
|
|
function getWriterIndex() {
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Returns true if the specified index is a valid server index
|
|
*/
|
|
function haveIndex( $i ) {
|
|
return array_key_exists( $i, $this->mServers );
|
|
}
|
|
|
|
/**
|
|
* Returns true if the specified index is valid and has non-zero load
|
|
*/
|
|
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)
|
|
*/
|
|
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.
|
|
*/
|
|
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.
|
|
*/
|
|
function getServerInfo( $i ) {
|
|
if ( isset( $this->mServers[$i] ) ) {
|
|
return $this->mServers[$i];
|
|
} else {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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(),
|
|
);
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
function closeConnecton( $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 ) {
|
|
$conn->commit();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* 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 $type => $conns2 ) {
|
|
if ( empty( $conns2[$masterIndex] ) ) {
|
|
continue;
|
|
}
|
|
foreach ( $conns2[$masterIndex] as $conn ) {
|
|
if ( $conn->doneWrites() ) {
|
|
$conn->commit();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
function waitTimeout( $value = null ) {
|
|
return wfSetVar( $this->mWaitTimeout, $value );
|
|
}
|
|
|
|
function getLaggedSlaveMode() {
|
|
return $this->mLaggedSlaveMode;
|
|
}
|
|
|
|
/* Disables/enables lag checks */
|
|
function allowLagged($mode=null) {
|
|
if ($mode===null)
|
|
return $this->mAllowLagged;
|
|
$this->mAllowLagged=$mode;
|
|
}
|
|
|
|
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
|
|
*/
|
|
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.
|
|
* @param $wiki string Wiki ID, or false for the default database
|
|
*/
|
|
function getMaxLag( $wiki = false ) {
|
|
$maxLag = -1;
|
|
$host = '';
|
|
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'];
|
|
}
|
|
}
|
|
return array( $host, $maxLag );
|
|
}
|
|
|
|
/**
|
|
* Get lag time for each server
|
|
* Results are cached for a short time in memcached, and indefinitely in the process cache
|
|
*/
|
|
function getLagTimes( $wiki = false ) {
|
|
# Try process cache
|
|
if ( isset( $this->mLagTimes ) ) {
|
|
return $this->mLagTimes;
|
|
}
|
|
# No, send the request to the load monitor
|
|
$this->mLagTimes = $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $wiki );
|
|
return $this->mLagTimes;
|
|
}
|
|
|
|
/**
|
|
* Clear the cache for getLagTimes
|
|
*/
|
|
function clearLagTimeCache() {
|
|
$this->mLagTimes = null;
|
|
}
|
|
}
|