--- /dev/null
+<?php
+/**
+ * @file
+ * @ingroup Database
+ */
+
+/**
+ * Database load balancing object
+ *
+ * @todo document
+ * @ingroup Database
+ */
+class LoadBalancer {
+ /* private */ var $mServers, $mConns, $mLoads, $mGroupLoads;
+ /* private */ var $mFailFunction, $mErrorConnection;
+ /* private */ var $mReadIndex, $mAllowLagged;
+ /* private */ var $mWaitForPos, $mWaitTimeout;
+ /* private */ var $mLaggedSlaveMode, $mLastError = 'Unknown error';
+ /* private */ var $mParentInfo, $mLagTimes;
+ /* private */ var $mLoadMonitorClass, $mLoadMonitor;
+
+ /**
+ * @param array $params Array with keys:
+ * servers Required. Array of server info structures.
+ * failFunction Deprecated, use exceptions instead.
+ * masterWaitTimeout Replication lag wait timeout
+ * loadMonitor Name of a class used to fetch server lag and load.
+ */
+ function __construct( $params )
+ {
+ if ( !isset( $params['servers'] ) ) {
+ throw new MWException( __CLASS__.': missing servers parameter' );
+ }
+ $this->mServers = $params['servers'];
+
+ if ( isset( $params['failFunction'] ) ) {
+ $this->mFailFunction = $params['failFunction'];
+ } else {
+ $this->mFailFunction = false;
+ }
+ if ( isset( $params['waitTimeout'] ) ) {
+ $this->mWaitTimeout = $params['waitTimeout'];
+ } else {
+ $this->mWaitTimeout = 10;
+ }
+
+ $this->mReadIndex = -1;
+ $this->mWriteIndex = -1;
+ $this->mConns = array(
+ 'local' => array(),
+ 'foreignUsed' => array(),
+ 'foreignFree' => array() );
+ $this->mLoads = array();
+ $this->mWaitForPos = false;
+ $this->mLaggedSlaveMode = false;
+ $this->mErrorConnection = false;
+ $this->mAllowLag = false;
+ $this->mLoadMonitorClass = isset( $params['loadMonitor'] )
+ ? $params['loadMonitor'] : 'LoadMonitor_MySQL';
+
+ foreach( $params['servers'] as $i => $server ) {
+ $this->mLoads[$i] = $server['load'];
+ if ( isset( $server['groupLoads'] ) ) {
+ foreach ( $server['groupLoads'] as $group => $ratio ) {
+ if ( !isset( $this->mGroupLoads[$group] ) ) {
+ $this->mGroupLoads[$group] = array();
+ }
+ $this->mGroupLoads[$group][$i] = $ratio;
+ }
+ }
+ }
+ }
+
+ static function newFromParams( $servers, $failFunction = false, $waitTimeout = 10 )
+ {
+ return new LoadBalancer( $servers, $failFunction, $waitTimeout );
+ }
+
+ /**
+ * Get a LoadMonitor instance
+ */
+ function getLoadMonitor() {
+ if ( !isset( $this->mLoadMonitor ) ) {
+ $class = $this->mLoadMonitorClass;
+ $this->mLoadMonitor = new $class( $this );
+ }
+ return $this->mLoadMonitor;
+ }
+
+ /**
+ * Get or set arbitrary data used by the parent object, usually an LBFactory
+ */
+ function parentInfo( $x = null ) {
+ return wfSetVar( $this->mParentInfo, $x );
+ }
+
+ /**
+ * Given an array of non-normalised probabilities, this function will select
+ * an element and return the appropriate key
+ */
+ function pickRandom( $weights )
+ {
+ if ( !is_array( $weights ) || count( $weights ) == 0 ) {
+ return false;
+ }
+
+ $sum = array_sum( $weights );
+ if ( $sum == 0 ) {
+ # No loads on any of them
+ # In previous versions, this triggered an unweighted random selection,
+ # but this feature has been removed as of April 2006 to allow for strict
+ # separation of query groups.
+ return false;
+ }
+ $max = mt_getrandmax();
+ $rand = mt_rand(0, $max) / $max * $sum;
+
+ $sum = 0;
+ foreach ( $weights as $i => $w ) {
+ $sum += $w;
+ if ( $sum >= $rand ) {
+ break;
+ }
+ }
+ return $i;
+ }
+
+ function getRandomNonLagged( $loads, $wiki = false ) {
+ # Unset excessively lagged servers
+ $lags = $this->getLagTimes( $wiki );
+ foreach ( $lags as $i => $lag ) {
+ if ( $i != 0 && isset( $this->mServers[$i]['max lag'] ) ) {
+ if ( $lag === false ) {
+ wfDebug( "Server #$i is not replicating\n" );
+ unset( $loads[$i] );
+ } elseif ( $lag > $this->mServers[$i]['max lag'] ) {
+ wfDebug( "Server #$i is excessively lagged ($lag seconds)\n" );
+ unset( $loads[$i] );
+ }
+ }
+ }
+
+ # Find out if all the slaves with non-zero load are lagged
+ $sum = 0;
+ foreach ( $loads as $load ) {
+ $sum += $load;
+ }
+ if ( $sum == 0 ) {
+ # No appropriate DB servers except maybe the master and some slaves with zero load
+ # Do NOT use the master
+ # Instead, this function will return false, triggering read-only mode,
+ # and a lagged slave will be used instead.
+ return false;
+ }
+
+ if ( count( $loads ) == 0 ) {
+ return false;
+ }
+
+ #wfDebugLog( 'connect', var_export( $loads, true ) );
+
+ # Return a random representative of the remainder
+ return $this->pickRandom( $loads );
+ }
+
+ /**
+ * Get the index of the reader connection, which may be a slave
+ * This takes into account load ratios and lag times. It should
+ * always return a consistent index during a given invocation
+ *
+ * Side effect: opens connections to databases
+ */
+ function getReaderIndex( $group = false, $wiki = false ) {
+ global $wgReadOnly, $wgDBClusterTimeout, $wgDBAvgStatusPoll, $wgDBtype;
+
+ # FIXME: For now, only go through all this for mysql databases
+ if ($wgDBtype != 'mysql') {
+ return $this->getWriterIndex();
+ }
+
+ if ( count( $this->mServers ) == 1 ) {
+ # Skip the load balancing if there's only one server
+ return 0;
+ } elseif ( $group === false and $this->mReadIndex >= 0 ) {
+ # Shortcut if generic reader exists already
+ return $this->mReadIndex;
+ }
+
+ wfProfileIn( __METHOD__ );
+
+ $totalElapsed = 0;
+
+ # convert from seconds to microseconds
+ $timeout = $wgDBClusterTimeout * 1e6;
+
+ # Find the relevant load array
+ if ( $group !== false ) {
+ if ( isset( $this->mGroupLoads[$group] ) ) {
+ $nonErrorLoads = $this->mGroupLoads[$group];
+ } else {
+ # No loads for this group, return false and the caller can use some other group
+ wfDebug( __METHOD__.": no loads for group $group\n" );
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+ } else {
+ $nonErrorLoads = $this->mLoads;
+ }
+
+ if ( !$nonErrorLoads ) {
+ throw new MWException( "Empty server array given to LoadBalancer" );
+ }
+
+ # Scale the configured load ratios according to the dynamic load (if the load monitor supports it)
+ $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $group, $wiki );
+
+ $i = false;
+ $found = false;
+ $laggedSlaveMode = false;
+
+ # First try quickly looking through the available servers for a server that
+ # meets our criteria
+ do {
+ $totalThreadsConnected = 0;
+ $overloadedServers = 0;
+ $currentLoads = $nonErrorLoads;
+ while ( count( $currentLoads ) ) {
+ if ( $wgReadOnly || $this->mAllowLagged || $laggedSlaveMode ) {
+ $i = $this->pickRandom( $currentLoads );
+ } else {
+ $i = $this->getRandomNonLagged( $currentLoads, $wiki );
+ if ( $i === false && count( $currentLoads ) != 0 ) {
+ # All slaves lagged. Switch to read-only mode
+ $wgReadOnly = wfMsgNoDBForContent( 'readonly_lag' );
+ $i = $this->pickRandom( $currentLoads );
+ $laggedSlaveMode = true;
+ }
+ }
+
+ if ( $i === false ) {
+ # pickRandom() returned false
+ # This is permanent and means the configuration or the load monitor
+ # wants us to return false.
+ wfDebugLog( 'connect', __METHOD__.": pickRandom() returned false\n" );
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+
+ wfDebugLog( 'connect', __METHOD__.": Using reader #$i: {$this->mServers[$i]['host']}...\n" );
+ $conn = $this->openConnection( $i, $wiki );
+
+ if ( !$conn ) {
+ wfDebugLog( 'connect', __METHOD__.": Failed connecting to $i/$wiki\n" );
+ unset( $nonErrorLoads[$i] );
+ unset( $currentLoads[$i] );
+ continue;
+ }
+
+ // Perform post-connection backoff
+ $threshold = isset( $this->mServers[$i]['max threads'] )
+ ? $this->mServers[$i]['max threads'] : false;
+ $backoff = $this->getLoadMonitor()->postConnectionBackoff( $conn, $threshold );
+
+ // Decrement reference counter, we are finished with this connection.
+ // It will be incremented for the caller later.
+ if ( $wiki !== false ) {
+ $this->reuseConnection( $conn );
+ }
+
+ if ( $backoff ) {
+ # Post-connection overload, don't use this server for now
+ $totalThreadsConnected += $backoff;
+ $overloadedServers++;
+ unset( $currentLoads[$i] );
+ } else {
+ # Return this server
+ break 2;
+ }
+ }
+
+ # No server found yet
+ $i = false;
+
+ # If all servers were down, quit now
+ if ( !count( $nonErrorLoads ) ) {
+ wfDebugLog( 'connect', "All servers down\n" );
+ break;
+ }
+
+ # Some servers must have been overloaded
+ if ( $overloadedServers == 0 ) {
+ throw new MWException( __METHOD__.": unexpectedly found no overloaded servers" );
+ }
+ # Back off for a while
+ # Scale the sleep time by the number of connected threads, to produce a
+ # roughly constant global poll rate
+ $avgThreads = $totalThreadsConnected / $overloadedServers;
+ $totalElapsed += $this->sleep( $wgDBAvgStatusPoll * $avgThreads );
+ } while ( $totalElapsed < $timeout );
+
+ if ( $totalElapsed >= $timeout ) {
+ wfDebugLog( 'connect', "All servers busy\n" );
+ $this->mErrorConnection = false;
+ $this->mLastError = 'All servers busy';
+ }
+
+ if ( $i !== false ) {
+ # Slave connection successful
+ # Wait for the session master pos for a short time
+ if ( $this->mWaitForPos && $i > 0 ) {
+ if ( !$this->doWait( $i ) ) {
+ $this->mServers[$i]['slave pos'] = $conn->getSlavePos();
+ }
+ }
+ if ( $this->mReadIndex <=0 && $this->mLoads[$i]>0 && $i !== false ) {
+ $this->mReadIndex = $i;
+ }
+ }
+ wfProfileOut( __METHOD__ );
+ return $i;
+ }
+
+ /**
+ * Wait for a specified number of microseconds, and return the period waited
+ */
+ function sleep( $t ) {
+ wfProfileIn( __METHOD__ );
+ wfDebug( __METHOD__.": waiting $t us\n" );
+ usleep( $t );
+ wfProfileOut( __METHOD__ );
+ return $t;
+ }
+
+ /**
+ * Get a random server to use in a query group
+ * @deprecated use getReaderIndex
+ */
+ function getGroupIndex( $group ) {
+ return $this->getReaderIndex( $group );
+ }
+
+ /**
+ * Set the master wait position
+ * If a DB_SLAVE connection has been opened already, waits
+ * Otherwise sets a variable telling it to wait if such a connection is opened
+ */
+ public function waitFor( $pos ) {
+ wfProfileIn( __METHOD__ );
+ $this->mWaitForPos = $pos;
+ $i = $this->mReadIndex;
+
+ if ( $i > 0 ) {
+ if ( !$this->doWait( $i ) ) {
+ $this->mServers[$i]['slave pos'] = $this->getAnyOpenConnection( $i )->getSlavePos();
+ $this->mLaggedSlaveMode = true;
+ }
+ }
+ wfProfileOut( __METHOD__ );
+ }
+
+ /**
+ * Get any open connection to a given server index, local or foreign
+ * Returns false if there is no connection open
+ */
+ function getAnyOpenConnection( $i ) {
+ foreach ( $this->mConns as $type => $conns ) {
+ if ( !empty( $conns[$i] ) ) {
+ return reset( $conns[$i] );
+ }
+ }
+ return false;
+ }
+
+ /**
+ * Wait for a given slave to catch up to the master pos stored in $this
+ */
+ function doWait( $index ) {
+ # Find a connection to wait on
+ $conn = $this->getAnyOpenConnection( $index );
+ if ( !$conn ) {
+ wfDebug( __METHOD__ . ": no connection open\n" );
+ return false;
+ }
+
+ wfDebug( __METHOD__.": Waiting for slave #$index to catch up...\n" );
+ $result = $conn->masterPosWait( $this->mWaitForPos, $this->mWaitTimeout );
+
+ if ( $result == -1 || is_null( $result ) ) {
+ # Timed out waiting for slave, use master instead
+ wfDebug( __METHOD__.": Timed out waiting for slave #$index pos {$this->mWaitForPos}\n" );
+ return false;
+ } else {
+ wfDebug( __METHOD__.": Done\n" );
+ return true;
+ }
+ }
+
+ /**
+ * Get a connection by index
+ * This is the main entry point for this class.
+ * @param int $i Database
+ * @param array $groups Query groups
+ * @param string $wiki Wiki ID
+ */
+ public function &getConnection( $i, $groups = array(), $wiki = false ) {
+ global $wgDBtype;
+ wfProfileIn( __METHOD__ );
+
+ if ( $i == DB_LAST ) {
+ throw new MWException( 'Attempt to call ' . __METHOD__ . ' with deprecated server index DB_LAST' );
+ } elseif ( $i === null || $i === false ) {
+ throw new MWException( 'Attempt to call ' . __METHOD__ . ' with invalid server index' );
+ }
+
+ if ( $wiki === wfWikiID() ) {
+ $wiki = false;
+ }
+
+ # Query groups
+ if ( $i == DB_MASTER ) {
+ $i = $this->getWriterIndex();
+ } elseif ( !is_array( $groups ) ) {
+ $groupIndex = $this->getReaderIndex( $groups, $wiki );
+ if ( $groupIndex !== false ) {
+ $serverName = $this->getServerName( $groupIndex );
+ wfDebug( __METHOD__.": using server $serverName for group $groups\n" );
+ $i = $groupIndex;
+ }
+ } else {
+ foreach ( $groups as $group ) {
+ $groupIndex = $this->getReaderIndex( $group, $wiki );
+ if ( $groupIndex !== false ) {
+ $serverName = $this->getServerName( $groupIndex );
+ wfDebug( __METHOD__.": using server $serverName for group $group\n" );
+ $i = $groupIndex;
+ break;
+ }
+ }
+ }
+
+ # Operation-based index
+ if ( $i == DB_SLAVE ) {
+ $i = $this->getReaderIndex( false, $wiki );
+ # Couldn't find a working server in getReaderIndex()?
+ if ( $i === false ) {
+ $this->mLastError = 'No working slave server: ' . $this->mLastError;
+ $this->reportConnectionError( $this->mErrorConnection );
+ return false;
+ }
+ }
+
+ # Now we have an explicit index into the servers array
+ $conn = $this->openConnection( $i, $wiki );
+ if ( !$conn ) {
+ $this->reportConnectionError( $this->mErrorConnection );
+ }
+
+ wfProfileOut( __METHOD__ );
+ return $conn;
+ }
+
+ /**
+ * Mark a foreign connection as being available for reuse under a different
+ * DB name or prefix. This mechanism is reference-counted, and must be called
+ * the same number of times as getConnection() to work.
+ */
+ public function reuseConnection( $conn ) {
+ $serverIndex = $conn->getLBInfo('serverIndex');
+ $refCount = $conn->getLBInfo('foreignPoolRefCount');
+ $dbName = $conn->getDBname();
+ $prefix = $conn->tablePrefix();
+ if ( strval( $prefix ) !== '' ) {
+ $wiki = "$dbName-$prefix";
+ } 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" );
+ }
+ }
+
+ /**
+ * 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 integer $i Server index
+ * @param string $wiki Wiki ID to open
+ * @return Database
+ *
+ * @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 integer $i Server index
+ * @param string $wiki Wiki ID to open
+ * @return Database
+ */
+ 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
+ * @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->immediateCommit();
+ }
+ }
+ }
+ }
+
+ /* 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->lastQuery() != '' ) {
+ $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.
+ */
+ function getMaxLag() {
+ $maxLag = -1;
+ $host = '';
+ foreach ( $this->mServers as $i => $conn ) {
+ $conn = $this->getAnyOpenConnection( $i );
+ if ( !$conn ) {
+ $conn = $this->openConnection( $i );
+ }
+ if ( !$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;
+ }
+}
scripts.mit.edu / autoinstalls / mediawiki.git / blobdiff