'ListToggle' => __DIR__ . '/includes/ListToggle.php',
'ListVariants' => __DIR__ . '/maintenance/language/listVariants.php',
'ListredirectsPage' => __DIR__ . '/includes/specials/SpecialListredirects.php',
- 'LoadBalancer' => __DIR__ . '/includes/db/loadbalancer/LoadBalancer.php',
+ 'LoadBalancer' => __DIR__ . '/includes/libs/rdbms/loadbalancer/LoadBalancer.php',
'LoadBalancerSingle' => __DIR__ . '/includes/db/loadbalancer/LBFactorySingle.php',
'LoadMonitor' => __DIR__ . '/includes/libs/rdbms/loadmonitor/LoadMonitor.php',
'LoadMonitorMySQL' => __DIR__ . '/includes/libs/rdbms/loadmonitor/LoadMonitorMySQL.php',
+++ /dev/null
-<?php
-/**
- * Database load balancing manager
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- * http://www.gnu.org/copyleft/gpl.html
- *
- * @file
- * @ingroup Database
- */
-use Psr\Log\LoggerInterface;
-
-/**
- * Database load balancing, tracking, and transaction management object
- *
- * @ingroup Database
- */
-class LoadBalancer implements ILoadBalancer {
- /** @var array[] Map of (server index => server config array) */
- private $mServers;
- /** @var array[] Map of (local/foreignUsed/foreignFree => server index => IDatabase array) */
- private $mConns;
- /** @var array Map of (server index => weight) */
- private $mLoads;
- /** @var array[] Map of (group => server index => weight) */
- private $mGroupLoads;
- /** @var bool Whether to disregard replica DB lag as a factor in replica DB selection */
- private $mAllowLagged;
- /** @var integer Seconds to spend waiting on replica DB lag to resolve */
- private $mWaitTimeout;
- /** @var string The LoadMonitor subclass name */
- private $mLoadMonitorClass;
-
- /** @var LoadMonitor */
- private $mLoadMonitor;
- /** @var BagOStuff */
- private $srvCache;
- /** @var BagOStuff */
- private $memCache;
- /** @var WANObjectCache */
- private $wanCache;
- /** @var TransactionProfiler */
- protected $trxProfiler;
- /** @var LoggerInterface */
- protected $replLogger;
- /** @var LoggerInterface */
- protected $connLogger;
- /** @var LoggerInterface */
- protected $queryLogger;
- /** @var LoggerInterface */
- protected $perfLogger;
-
- /** @var bool|IDatabase Database connection that caused a problem */
- private $mErrorConnection;
- /** @var integer The generic (not query grouped) replica DB index (of $mServers) */
- private $mReadIndex;
- /** @var bool|DBMasterPos False if not set */
- private $mWaitForPos;
- /** @var bool Whether the generic reader fell back to a lagged replica DB */
- private $laggedReplicaMode = false;
- /** @var bool Whether the generic reader fell back to a lagged replica DB */
- private $allReplicasDownMode = false;
- /** @var string The last DB selection or connection error */
- private $mLastError = 'Unknown error';
- /** @var string|bool Reason the LB is read-only or false if not */
- private $readOnlyReason = false;
- /** @var integer Total connections opened */
- private $connsOpened = 0;
- /** @var string|bool String if a requested DBO_TRX transaction round is active */
- private $trxRoundId = false;
- /** @var array[] Map of (name => callable) */
- private $trxRecurringCallbacks = [];
- /** @var string Local Domain ID and default for selectDB() calls */
- private $localDomain;
- /** @var string Current server name */
- private $host;
-
- /** @var callable Exception logger */
- private $errorLogger;
-
- /** @var boolean */
- private $disabled = false;
-
- /** @var integer Warn when this many connection are held */
- const CONN_HELD_WARN_THRESHOLD = 10;
- /** @var integer Default 'max lag' when unspecified */
- const MAX_LAG_DEFAULT = 10;
- /** @var integer Max time to wait for a replica DB to catch up (e.g. ChronologyProtector) */
- const POS_WAIT_TIMEOUT = 10;
- /** @var integer Seconds to cache master server read-only status */
- const TTL_CACHE_READONLY = 5;
-
- public function __construct( array $params ) {
- if ( !isset( $params['servers'] ) ) {
- throw new InvalidArgumentException( __CLASS__ . ': missing servers parameter' );
- }
- $this->mServers = $params['servers'];
- $this->mWaitTimeout = isset( $params['waitTimeout'] )
- ? $params['waitTimeout']
- : self::POS_WAIT_TIMEOUT;
- $this->localDomain = isset( $params['localDomain'] ) ? $params['localDomain'] : '';
-
- $this->mReadIndex = -1;
- $this->mConns = [
- 'local' => [],
- 'foreignUsed' => [],
- 'foreignFree' => [] ];
- $this->mLoads = [];
- $this->mWaitForPos = false;
- $this->mErrorConnection = false;
- $this->mAllowLagged = false;
-
- if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) {
- $this->readOnlyReason = $params['readOnlyReason'];
- }
-
- if ( isset( $params['loadMonitor'] ) ) {
- $this->mLoadMonitorClass = $params['loadMonitor'];
- } else {
- $master = reset( $params['servers'] );
- if ( isset( $master['type'] ) && $master['type'] === 'mysql' ) {
- $this->mLoadMonitorClass = 'LoadMonitorMySQL';
- } else {
- $this->mLoadMonitorClass = 'LoadMonitorNull';
- }
- }
-
- 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] = [];
- }
- $this->mGroupLoads[$group][$i] = $ratio;
- }
- }
- }
-
- if ( isset( $params['srvCache'] ) ) {
- $this->srvCache = $params['srvCache'];
- } else {
- $this->srvCache = new EmptyBagOStuff();
- }
- if ( isset( $params['memCache'] ) ) {
- $this->memCache = $params['memCache'];
- } else {
- $this->memCache = new EmptyBagOStuff();
- }
- if ( isset( $params['wanCache'] ) ) {
- $this->wanCache = $params['wanCache'];
- } else {
- $this->wanCache = WANObjectCache::newEmpty();
- }
- if ( isset( $params['trxProfiler'] ) ) {
- $this->trxProfiler = $params['trxProfiler'];
- } else {
- $this->trxProfiler = new TransactionProfiler();
- }
-
- $this->errorLogger = isset( $params['errorLogger'] )
- ? $params['errorLogger']
- : function ( Exception $e ) {
- trigger_error( E_WARNING, $e->getMessage() );
- };
-
- foreach ( [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ] as $key ) {
- $this->$key = isset( $params[$key] ) ? $params[$key] : new \Psr\Log\NullLogger();
- }
-
- $this->host = isset( $params['hostname'] )
- ? $params['hostname']
- : ( gethostname() ?: 'unknown' );
- }
-
- /**
- * Get a LoadMonitor instance
- *
- * @return LoadMonitor
- */
- private function getLoadMonitor() {
- if ( !isset( $this->mLoadMonitor ) ) {
- $class = $this->mLoadMonitorClass;
- $this->mLoadMonitor = new $class( $this, $this->srvCache, $this->memCache );
- $this->mLoadMonitor->setLogger( $this->replLogger );
- }
-
- return $this->mLoadMonitor;
- }
-
- /**
- * @param array $loads
- * @param bool|string $domain Domain to get non-lagged for
- * @param int $maxLag Restrict the maximum allowed lag to this many seconds
- * @return bool|int|string
- */
- private function getRandomNonLagged( array $loads, $domain = false, $maxLag = INF ) {
- $lags = $this->getLagTimes( $domain );
-
- # Unset excessively lagged servers
- foreach ( $lags as $i => $lag ) {
- if ( $i != 0 ) {
- # How much lag this server nominally is allowed to have
- $maxServerLag = isset( $this->mServers[$i]['max lag'] )
- ? $this->mServers[$i]['max lag']
- : self::MAX_LAG_DEFAULT; // default
- # Constrain that futher by $maxLag argument
- $maxServerLag = min( $maxServerLag, $maxLag );
-
- $host = $this->getServerName( $i );
- if ( $lag === false && !is_infinite( $maxServerLag ) ) {
- $this->replLogger->error( "Server $host (#$i) is not replicating?" );
- unset( $loads[$i] );
- } elseif ( $lag > $maxServerLag ) {
- $this->replLogger->warning( "Server $host (#$i) has >= $lag seconds of lag" );
- unset( $loads[$i] );
- }
- }
- }
-
- # Find out if all the replica DBs 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 replica DBs with zero load
- # Do NOT use the master
- # Instead, this function will return false, triggering read-only mode,
- # and a lagged replica DB will be used instead.
- return false;
- }
-
- if ( count( $loads ) == 0 ) {
- return false;
- }
-
- # Return a random representative of the remainder
- return ArrayUtils::pickRandom( $loads );
- }
-
- public function getReaderIndex( $group = false, $domain = false ) {
- if ( count( $this->mServers ) == 1 ) {
- # Skip the load balancing if there's only one server
- return $this->getWriterIndex();
- } elseif ( $group === false && $this->mReadIndex >= 0 ) {
- # Shortcut if generic reader exists already
- return $this->mReadIndex;
- }
-
- # 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
- $this->connLogger->info( __METHOD__ . ": no loads for group $group" );
-
- return false;
- }
- } else {
- $nonErrorLoads = $this->mLoads;
- }
-
- if ( !count( $nonErrorLoads ) ) {
- throw new InvalidArgumentException( "Empty server array given to LoadBalancer" );
- }
-
- # Scale the configured load ratios according to the dynamic load if supported
- $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $group, $domain );
-
- $laggedReplicaMode = false;
-
- # No server found yet
- $i = false;
- # First try quickly looking through the available servers for a server that
- # meets our criteria
- $currentLoads = $nonErrorLoads;
- while ( count( $currentLoads ) ) {
- if ( $this->mAllowLagged || $laggedReplicaMode ) {
- $i = ArrayUtils::pickRandom( $currentLoads );
- } else {
- $i = false;
- if ( $this->mWaitForPos && $this->mWaitForPos->asOfTime() ) {
- # ChronologyProtecter causes mWaitForPos to be set via sessions.
- # This triggers doWait() after connect, so it's especially good to
- # avoid lagged servers so as to avoid just blocking in that method.
- $ago = microtime( true ) - $this->mWaitForPos->asOfTime();
- # Aim for <= 1 second of waiting (being too picky can backfire)
- $i = $this->getRandomNonLagged( $currentLoads, $domain, $ago + 1 );
- }
- if ( $i === false ) {
- # Any server with less lag than it's 'max lag' param is preferable
- $i = $this->getRandomNonLagged( $currentLoads, $domain );
- }
- if ( $i === false && count( $currentLoads ) != 0 ) {
- # All replica DBs lagged. Switch to read-only mode
- $this->replLogger->error( "All replica DBs lagged. Switch to read-only mode" );
- $i = ArrayUtils::pickRandom( $currentLoads );
- $laggedReplicaMode = true;
- }
- }
-
- if ( $i === false ) {
- # pickRandom() returned false
- # This is permanent and means the configuration or the load monitor
- # wants us to return false.
- $this->connLogger->debug( __METHOD__ . ": pickRandom() returned false" );
-
- return false;
- }
-
- $serverName = $this->getServerName( $i );
- $this->connLogger->debug( __METHOD__ . ": Using reader #$i: $serverName..." );
-
- $conn = $this->openConnection( $i, $domain );
- if ( !$conn ) {
- $this->connLogger->warning( __METHOD__ . ": Failed connecting to $i/$domain" );
- unset( $nonErrorLoads[$i] );
- unset( $currentLoads[$i] );
- $i = false;
- continue;
- }
-
- // Decrement reference counter, we are finished with this connection.
- // It will be incremented for the caller later.
- if ( $domain !== false ) {
- $this->reuseConnection( $conn );
- }
-
- # Return this server
- break;
- }
-
- # If all servers were down, quit now
- if ( !count( $nonErrorLoads ) ) {
- $this->connLogger->error( "All servers down" );
- }
-
- if ( $i !== false ) {
- # Replica DB connection successful.
- # Wait for the session master pos for a short time.
- if ( $this->mWaitForPos && $i > 0 ) {
- $this->doWait( $i );
- }
- if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $group === false ) {
- $this->mReadIndex = $i;
- # Record if the generic reader index is in "lagged replica DB" mode
- if ( $laggedReplicaMode ) {
- $this->laggedReplicaMode = true;
- }
- }
- $serverName = $this->getServerName( $i );
- $this->connLogger->debug(
- __METHOD__ . ": using server $serverName for group '$group'" );
- }
-
- return $i;
- }
-
- public function waitFor( $pos ) {
- $this->mWaitForPos = $pos;
- $i = $this->mReadIndex;
-
- if ( $i > 0 ) {
- if ( !$this->doWait( $i ) ) {
- $this->laggedReplicaMode = true;
- }
- }
- }
-
- /**
- * Set the master wait position and wait for a "generic" replica DB to catch up to it
- *
- * This can be used a faster proxy for waitForAll()
- *
- * @param DBMasterPos $pos
- * @param int $timeout Max seconds to wait; default is mWaitTimeout
- * @return bool Success (able to connect and no timeouts reached)
- * @since 1.26
- */
- public function waitForOne( $pos, $timeout = null ) {
- $this->mWaitForPos = $pos;
-
- $i = $this->mReadIndex;
- if ( $i <= 0 ) {
- // Pick a generic replica DB if there isn't one yet
- $readLoads = $this->mLoads;
- unset( $readLoads[$this->getWriterIndex()] ); // replica DBs only
- $readLoads = array_filter( $readLoads ); // with non-zero load
- $i = ArrayUtils::pickRandom( $readLoads );
- }
-
- if ( $i > 0 ) {
- $ok = $this->doWait( $i, true, $timeout );
- } else {
- $ok = true; // no applicable loads
- }
-
- return $ok;
- }
-
- public function waitForAll( $pos, $timeout = null ) {
- $this->mWaitForPos = $pos;
- $serverCount = count( $this->mServers );
-
- $ok = true;
- for ( $i = 1; $i < $serverCount; $i++ ) {
- if ( $this->mLoads[$i] > 0 ) {
- $ok = $this->doWait( $i, true, $timeout ) && $ok;
- }
- }
-
- return $ok;
- }
-
- public function getAnyOpenConnection( $i ) {
- foreach ( $this->mConns as $connsByServer ) {
- if ( !empty( $connsByServer[$i] ) ) {
- return reset( $connsByServer[$i] );
- }
- }
-
- return false;
- }
-
- /**
- * Wait for a given replica DB to catch up to the master pos stored in $this
- * @param int $index Server index
- * @param bool $open Check the server even if a new connection has to be made
- * @param int $timeout Max seconds to wait; default is mWaitTimeout
- * @return bool
- */
- protected function doWait( $index, $open = false, $timeout = null ) {
- $close = false; // close the connection afterwards
-
- // Check if we already know that the DB has reached this point
- $server = $this->getServerName( $index );
- $key = $this->srvCache->makeGlobalKey( __CLASS__, 'last-known-pos', $server );
- /** @var DBMasterPos $knownReachedPos */
- $knownReachedPos = $this->srvCache->get( $key );
- if ( $knownReachedPos && $knownReachedPos->hasReached( $this->mWaitForPos ) ) {
- $this->replLogger->debug( __METHOD__ .
- ": replica DB $server known to be caught up (pos >= $knownReachedPos)." );
- return true;
- }
-
- // Find a connection to wait on, creating one if needed and allowed
- $conn = $this->getAnyOpenConnection( $index );
- if ( !$conn ) {
- if ( !$open ) {
- $this->replLogger->debug( __METHOD__ . ": no connection open for $server" );
-
- return false;
- } else {
- $conn = $this->openConnection( $index, '' );
- if ( !$conn ) {
- $this->replLogger->warning( __METHOD__ . ": failed to connect to $server" );
-
- return false;
- }
- // Avoid connection spam in waitForAll() when connections
- // are made just for the sake of doing this lag check.
- $close = true;
- }
- }
-
- $this->replLogger->info( __METHOD__ . ": Waiting for replica DB $server to catch up..." );
- $timeout = $timeout ?: $this->mWaitTimeout;
- $result = $conn->masterPosWait( $this->mWaitForPos, $timeout );
-
- if ( $result == -1 || is_null( $result ) ) {
- // Timed out waiting for replica DB, use master instead
- $msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
- $this->replLogger->warning( "$msg" );
- $ok = false;
- } else {
- $this->replLogger->info( __METHOD__ . ": Done" );
- $ok = true;
- // Remember that the DB reached this point
- $this->srvCache->set( $key, $this->mWaitForPos, BagOStuff::TTL_DAY );
- }
-
- if ( $close ) {
- $this->closeConnection( $conn );
- }
-
- return $ok;
- }
-
- public function getConnection( $i, $groups = [], $domain = false ) {
- if ( $i === null || $i === false ) {
- throw new InvalidArgumentException( 'Attempt to call ' . __METHOD__ .
- ' with invalid server index' );
- }
-
- if ( $domain === $this->localDomain ) {
- $domain = false;
- }
-
- $groups = ( $groups === false || $groups === [] )
- ? [ false ] // check one "group": the generic pool
- : (array)$groups;
-
- $masterOnly = ( $i == DB_MASTER || $i == $this->getWriterIndex() );
- $oldConnsOpened = $this->connsOpened; // connections open now
-
- if ( $i == DB_MASTER ) {
- $i = $this->getWriterIndex();
- } else {
- # Try to find an available server in any the query groups (in order)
- foreach ( $groups as $group ) {
- $groupIndex = $this->getReaderIndex( $group, $domain );
- if ( $groupIndex !== false ) {
- $i = $groupIndex;
- break;
- }
- }
- }
-
- # Operation-based index
- if ( $i == DB_REPLICA ) {
- $this->mLastError = 'Unknown error'; // reset error string
- # Try the general server pool if $groups are unavailable.
- $i = in_array( false, $groups, true )
- ? false // don't bother with this if that is what was tried above
- : $this->getReaderIndex( false, $domain );
- # Couldn't find a working server in getReaderIndex()?
- if ( $i === false ) {
- $this->mLastError = 'No working replica DB server: ' . $this->mLastError;
-
- return $this->reportConnectionError();
- }
- }
-
- # Now we have an explicit index into the servers array
- $conn = $this->openConnection( $i, $domain );
- if ( !$conn ) {
- return $this->reportConnectionError();
- }
-
- # Profile any new connections that happen
- if ( $this->connsOpened > $oldConnsOpened ) {
- $host = $conn->getServer();
- $dbname = $conn->getDBname();
- $this->trxProfiler->recordConnection( $host, $dbname, $masterOnly );
- }
-
- if ( $masterOnly ) {
- # Make master-requested DB handles inherit any read-only mode setting
- $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $domain, $conn ) );
- }
-
- return $conn;
- }
-
- public function reuseConnection( $conn ) {
- $serverIndex = $conn->getLBInfo( 'serverIndex' );
- $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
- if ( $serverIndex === null || $refCount === null ) {
- /**
- * This can happen in code like:
- * foreach ( $dbs as $db ) {
- * $conn = $lb->getConnection( DB_REPLICA, [], $db );
- * ...
- * $lb->reuseConnection( $conn );
- * }
- * When a connection to the local DB is opened in this way, reuseConnection()
- * should be ignored
- */
- return;
- }
-
- $dbName = $conn->getDBname();
- $prefix = $conn->tablePrefix();
- if ( strval( $prefix ) !== '' ) {
- $domain = "$dbName-$prefix";
- } else {
- $domain = $dbName;
- }
- if ( $this->mConns['foreignUsed'][$serverIndex][$domain] !== $conn ) {
- throw new InvalidArgumentException( __METHOD__ . ": connection not found, has " .
- "the connection been freed already?" );
- }
- $conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
- if ( $refCount <= 0 ) {
- $this->mConns['foreignFree'][$serverIndex][$domain] = $conn;
- unset( $this->mConns['foreignUsed'][$serverIndex][$domain] );
- $this->connLogger->debug( __METHOD__ . ": freed connection $serverIndex/$domain" );
- } else {
- $this->connLogger->debug( __METHOD__ .
- ": reference count for $serverIndex/$domain reduced to $refCount" );
- }
- }
-
- /**
- * Get a database connection handle reference
- *
- * The handle's methods wrap simply wrap those of a IDatabase handle
- *
- * @see LoadBalancer::getConnection() for parameter information
- *
- * @param int $db
- * @param array|string|bool $groups Query group(s), or false for the generic reader
- * @param string|bool $domain Domain ID, or false for the current domain
- * @return DBConnRef
- * @since 1.22
- */
- public function getConnectionRef( $db, $groups = [], $domain = false ) {
- return new DBConnRef( $this, $this->getConnection( $db, $groups, $domain ) );
- }
-
- /**
- * Get a database connection handle reference without connecting yet
- *
- * The handle's methods wrap simply wrap those of a IDatabase handle
- *
- * @see LoadBalancer::getConnection() for parameter information
- *
- * @param int $db
- * @param array|string|bool $groups Query group(s), or false for the generic reader
- * @param string|bool $domain Domain ID, or false for the current domain
- * @return DBConnRef
- * @since 1.22
- */
- public function getLazyConnectionRef( $db, $groups = [], $domain = false ) {
- $domain = ( $domain !== false ) ? $domain : $this->localDomain;
-
- return new DBConnRef( $this, [ $db, $groups, $domain ] );
- }
-
- public function openConnection( $i, $domain = false ) {
- if ( $domain !== false ) {
- $conn = $this->openForeignConnection( $i, $domain );
- } elseif ( 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 );
- $serverName = $this->getServerName( $i );
- if ( $conn->isOpen() ) {
- $this->connLogger->debug( "Connected to database $i at '$serverName'." );
- $this->mConns['local'][$i][0] = $conn;
- } else {
- $this->connLogger->warning( "Failed to connect to database $i at '$serverName'." );
- $this->mErrorConnection = $conn;
- $conn = false;
- }
- }
-
- if ( $conn && !$conn->isOpen() ) {
- // Connection was made but later unrecoverably lost for some reason.
- // Do not return a handle that will just throw exceptions on use,
- // but let the calling code (e.g. getReaderIndex) try another server.
- // See DatabaseMyslBase::ping() for how this can happen.
- $this->mErrorConnection = $conn;
- $conn = false;
- }
-
- 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 domain. 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.
- *
- * @note If disable() was called on this LoadBalancer, this method will throw a DBAccessError.
- *
- * @param int $i Server index
- * @param string $domain Domain ID to open
- * @return IDatabase
- */
- private function openForeignConnection( $i, $domain ) {
- list( $dbName, $prefix ) = explode( '-', $domain, 2 ) + [ '', '' ];
-
- if ( isset( $this->mConns['foreignUsed'][$i][$domain] ) ) {
- // Reuse an already-used connection
- $conn = $this->mConns['foreignUsed'][$i][$domain];
- $this->connLogger->debug( __METHOD__ . ": reusing connection $i/$domain" );
- } elseif ( isset( $this->mConns['foreignFree'][$i][$domain] ) ) {
- // Reuse a free connection for the same domain
- $conn = $this->mConns['foreignFree'][$i][$domain];
- unset( $this->mConns['foreignFree'][$i][$domain] );
- $this->mConns['foreignUsed'][$i][$domain] = $conn;
- $this->connLogger->debug( __METHOD__ . ": reusing free connection $i/$domain" );
- } elseif ( !empty( $this->mConns['foreignFree'][$i] ) ) {
- // Reuse a connection from another domain
- $conn = reset( $this->mConns['foreignFree'][$i] );
- $oldDomain = key( $this->mConns['foreignFree'][$i] );
-
- // The empty string as a DB name means "don't care".
- // DatabaseMysqlBase::open() already handle this on connection.
- if ( $dbName !== '' && !$conn->selectDB( $dbName ) ) {
- $this->mLastError = "Error selecting database $dbName on server " .
- $conn->getServer() . " from client host {$this->host}";
- $this->mErrorConnection = $conn;
- $conn = false;
- } else {
- $conn->tablePrefix( $prefix );
- unset( $this->mConns['foreignFree'][$i][$oldDomain] );
- $this->mConns['foreignUsed'][$i][$domain] = $conn;
- $this->connLogger->debug( __METHOD__ .
- ": reusing free connection from $oldDomain for $domain" );
- }
- } 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() ) {
- $this->connLogger->warning( __METHOD__ . ": connection error for $i/$domain" );
- $this->mErrorConnection = $conn;
- $conn = false;
- } else {
- $conn->tablePrefix( $prefix );
- $this->mConns['foreignUsed'][$i][$domain] = $conn;
- $this->connLogger->debug( __METHOD__ . ": opened new connection for $i/$domain" );
- }
- }
-
- // Increment reference count
- if ( $conn ) {
- $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
- $conn->setLBInfo( 'foreignPoolRefCount', $refCount + 1 );
- }
-
- return $conn;
- }
-
- /**
- * Test if the specified index represents an open connection
- *
- * @param int $index Server index
- * @access private
- * @return bool
- */
- 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
- *
- * @param array $server
- * @param bool $dbNameOverride
- * @return IDatabase
- * @throws DBAccessError
- * @throws MWException
- */
- protected function reallyOpenConnection( $server, $dbNameOverride = false ) {
- if ( $this->disabled ) {
- throw new DBAccessError();
- }
-
- if ( !is_array( $server ) ) {
- throw new InvalidArgumentException(
- 'You must update your load-balancing configuration. ' .
- 'See DefaultSettings.php entry for $wgDBservers.' );
- }
-
- if ( $dbNameOverride !== false ) {
- $server['dbname'] = $dbNameOverride;
- }
-
- // Let the handle know what the cluster master is (e.g. "db1052")
- $masterName = $this->getServerName( $this->getWriterIndex() );
- $server['clusterMasterHost'] = $masterName;
-
- // Log when many connection are made on requests
- if ( ++$this->connsOpened >= self::CONN_HELD_WARN_THRESHOLD ) {
- $this->perfLogger->warning( __METHOD__ . ": " .
- "{$this->connsOpened}+ connections made (master=$masterName)" );
- }
-
- // Set loggers
- $server['connLogger'] = $this->connLogger;
- $server['queryLogger'] = $this->queryLogger;
- $server['trxProfiler'] = $this->trxProfiler;
-
- // Create a live connection 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 );
- $db->setLazyMasterHandle(
- $this->getLazyConnectionRef( DB_MASTER, [], $db->getWikiID() )
- );
-
- if ( $server['serverIndex'] === $this->getWriterIndex() ) {
- if ( $this->trxRoundId !== false ) {
- $this->applyTransactionRoundFlags( $db );
- }
- foreach ( $this->trxRecurringCallbacks as $name => $callback ) {
- $db->setTransactionListener( $name, $callback );
- }
- }
-
- return $db;
- }
-
- /**
- * @throws DBConnectionError
- * @return bool
- */
- private function reportConnectionError() {
- $conn = $this->mErrorConnection; // The connection which caused the error
- $context = [
- 'method' => __METHOD__,
- 'last_error' => $this->mLastError,
- ];
-
- if ( !is_object( $conn ) ) {
- // No last connection, probably due to all servers being too busy
- $this->connLogger->error(
- "LB failure with no last connection. Connection error: {last_error}",
- $context
- );
-
- // If all servers were busy, mLastError will contain something sensible
- throw new DBConnectionError( null, $this->mLastError );
- } else {
- $context['db_server'] = $conn->getProperty( 'mServer' );
- $this->connLogger->warning(
- "Connection error: {last_error} ({db_server})",
- $context
- );
-
- // throws DBConnectionError
- $conn->reportConnectionError( "{$this->mLastError} ({$context['db_server']})" );
- }
-
- return false; /* not reached */
- }
-
- public function getWriterIndex() {
- return 0;
- }
-
- public function haveIndex( $i ) {
- return array_key_exists( $i, $this->mServers );
- }
-
- public function isNonZeroLoad( $i ) {
- return array_key_exists( $i, $this->mServers ) && $this->mLoads[$i] != 0;
- }
-
- public function getServerCount() {
- return count( $this->mServers );
- }
-
- public function getServerName( $i ) {
- if ( isset( $this->mServers[$i]['hostName'] ) ) {
- $name = $this->mServers[$i]['hostName'];
- } elseif ( isset( $this->mServers[$i]['host'] ) ) {
- $name = $this->mServers[$i]['host'];
- } else {
- $name = '';
- }
-
- return ( $name != '' ) ? $name : 'localhost';
- }
-
- public function getServerInfo( $i ) {
- if ( isset( $this->mServers[$i] ) ) {
- return $this->mServers[$i];
- } else {
- return false;
- }
- }
-
- public function setServerInfo( $i, array $serverInfo ) {
- $this->mServers[$i] = $serverInfo;
- }
-
- public function getMasterPos() {
- # If this entire request was served from a replica DB without opening a connection to the
- # master (however unlikely that may be), then we can fetch the position from the replica DB.
- $masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
- if ( !$masterConn ) {
- $serverCount = count( $this->mServers );
- for ( $i = 1; $i < $serverCount; $i++ ) {
- $conn = $this->getAnyOpenConnection( $i );
- if ( $conn ) {
- return $conn->getSlavePos();
- }
- }
- } else {
- return $masterConn->getMasterPos();
- }
-
- return false;
- }
-
- /**
- * Disable this load balancer. All connections are closed, and any attempt to
- * open a new connection will result in a DBAccessError.
- *
- * @since 1.27
- */
- public function disable() {
- $this->closeAll();
- $this->disabled = true;
- }
-
- public function closeAll() {
- $this->forEachOpenConnection( function ( IDatabase $conn ) {
- $conn->close();
- } );
-
- $this->mConns = [
- 'local' => [],
- 'foreignFree' => [],
- 'foreignUsed' => [],
- ];
- $this->connsOpened = 0;
- }
-
- public function closeConnection( IDatabase $conn ) {
- $serverIndex = $conn->getLBInfo( 'serverIndex' ); // second index level of mConns
- foreach ( $this->mConns as $type => $connsByServer ) {
- if ( !isset( $connsByServer[$serverIndex] ) ) {
- continue;
- }
-
- foreach ( $connsByServer[$serverIndex] as $i => $trackedConn ) {
- if ( $conn === $trackedConn ) {
- unset( $this->mConns[$type][$serverIndex][$i] );
- --$this->connsOpened;
- break 2;
- }
- }
- }
-
- $conn->close();
- }
-
- public function commitAll( $fname = __METHOD__ ) {
- $failures = [];
-
- $restore = ( $this->trxRoundId !== false );
- $this->trxRoundId = false;
- $this->forEachOpenConnection(
- function ( IDatabase $conn ) use ( $fname, $restore, &$failures ) {
- try {
- $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS );
- } catch ( DBError $e ) {
- call_user_func( $this->errorLogger, $e );
- $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
- }
- if ( $restore && $conn->getLBInfo( 'master' ) ) {
- $this->undoTransactionRoundFlags( $conn );
- }
- }
- );
-
- if ( $failures ) {
- throw new DBExpectedError(
- null,
- "Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
- );
- }
- }
-
- /**
- * Perform all pre-commit callbacks that remain part of the atomic transactions
- * and disable any post-commit callbacks until runMasterPostTrxCallbacks()
- * @since 1.28
- */
- public function finalizeMasterChanges() {
- $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) {
- // Any error should cause all DB transactions to be rolled back together
- $conn->setTrxEndCallbackSuppression( false );
- $conn->runOnTransactionPreCommitCallbacks();
- // Defer post-commit callbacks until COMMIT finishes for all DBs
- $conn->setTrxEndCallbackSuppression( true );
- } );
- }
-
- /**
- * Perform all pre-commit checks for things like replication safety
- * @param array $options Includes:
- * - maxWriteDuration : max write query duration time in seconds
- * @throws DBTransactionError
- * @since 1.28
- */
- public function approveMasterChanges( array $options ) {
- $limit = isset( $options['maxWriteDuration'] ) ? $options['maxWriteDuration'] : 0;
- $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( $limit ) {
- // If atomic sections or explicit transactions are still open, some caller must have
- // caught an exception but failed to properly rollback any changes. Detect that and
- // throw and error (causing rollback).
- if ( $conn->explicitTrxActive() ) {
- throw new DBTransactionError(
- $conn,
- "Explicit transaction still active. A caller may have caught an error."
- );
- }
- // Assert that the time to replicate the transaction will be sane.
- // If this fails, then all DB transactions will be rollback back together.
- $time = $conn->pendingWriteQueryDuration( $conn::ESTIMATE_DB_APPLY );
- if ( $limit > 0 && $time > $limit ) {
- throw new DBTransactionSizeError(
- $conn,
- "Transaction spent $time second(s) in writes, exceeding the $limit limit.",
- [ $time, $limit ]
- );
- }
- // If a connection sits idle while slow queries execute on another, that connection
- // may end up dropped before the commit round is reached. Ping servers to detect this.
- if ( $conn->writesOrCallbacksPending() && !$conn->ping() ) {
- throw new DBTransactionError(
- $conn,
- "A connection to the {$conn->getDBname()} database was lost before commit."
- );
- }
- } );
- }
-
- /**
- * Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set)
- *
- * The DBO_TRX setting will be reverted to the default in each of these methods:
- * - commitMasterChanges()
- * - rollbackMasterChanges()
- * - commitAll()
- * This allows for custom transaction rounds from any outer transaction scope.
- *
- * @param string $fname
- * @throws DBExpectedError
- * @since 1.28
- */
- public function beginMasterChanges( $fname = __METHOD__ ) {
- if ( $this->trxRoundId !== false ) {
- throw new DBTransactionError(
- null,
- "$fname: Transaction round '{$this->trxRoundId}' already started."
- );
- }
- $this->trxRoundId = $fname;
-
- $failures = [];
- $this->forEachOpenMasterConnection(
- function ( DatabaseBase $conn ) use ( $fname, &$failures ) {
- $conn->setTrxEndCallbackSuppression( true );
- try {
- $conn->flushSnapshot( $fname );
- } catch ( DBError $e ) {
- call_user_func( $this->errorLogger, $e );
- $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
- }
- $conn->setTrxEndCallbackSuppression( false );
- $this->applyTransactionRoundFlags( $conn );
- }
- );
-
- if ( $failures ) {
- throw new DBExpectedError(
- null,
- "$fname: Flush failed on server(s) " . implode( "\n", array_unique( $failures ) )
- );
- }
- }
-
- public function commitMasterChanges( $fname = __METHOD__ ) {
- $failures = [];
-
- $restore = ( $this->trxRoundId !== false );
- $this->trxRoundId = false;
- $this->forEachOpenMasterConnection(
- function ( IDatabase $conn ) use ( $fname, $restore, &$failures ) {
- try {
- if ( $conn->writesOrCallbacksPending() ) {
- $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS );
- } elseif ( $restore ) {
- $conn->flushSnapshot( $fname );
- }
- } catch ( DBError $e ) {
- call_user_func( $this->errorLogger, $e );
- $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
- }
- if ( $restore ) {
- $this->undoTransactionRoundFlags( $conn );
- }
- }
- );
-
- if ( $failures ) {
- throw new DBExpectedError(
- null,
- "$fname: Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
- );
- }
- }
-
- /**
- * Issue all pending post-COMMIT/ROLLBACK callbacks
- * @param integer $type IDatabase::TRIGGER_* constant
- * @return Exception|null The first exception or null if there were none
- * @since 1.28
- */
- public function runMasterPostTrxCallbacks( $type ) {
- $e = null; // first exception
- $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) use ( $type, &$e ) {
- $conn->setTrxEndCallbackSuppression( false );
- if ( $conn->writesOrCallbacksPending() ) {
- // This happens if onTransactionIdle() callbacks leave callbacks on *another* DB
- // (which finished its callbacks already). Warn and recover in this case. Let the
- // callbacks run in the final commitMasterChanges() in LBFactory::shutdown().
- $this->queryLogger->error( __METHOD__ . ": found writes/callbacks pending." );
- return;
- } elseif ( $conn->trxLevel() ) {
- // This happens for single-DB setups where DB_REPLICA uses the master DB,
- // thus leaving an implicit read-only transaction open at this point. It
- // also happens if onTransactionIdle() callbacks leave implicit transactions
- // open on *other* DBs (which is slightly improper). Let these COMMIT on the
- // next call to commitMasterChanges(), possibly in LBFactory::shutdown().
- return;
- }
- try {
- $conn->runOnTransactionIdleCallbacks( $type );
- } catch ( Exception $ex ) {
- $e = $e ?: $ex;
- }
- try {
- $conn->runTransactionListenerCallbacks( $type );
- } catch ( Exception $ex ) {
- $e = $e ?: $ex;
- }
- } );
-
- return $e;
- }
-
- /**
- * Issue ROLLBACK only on master, only if queries were done on connection
- * @param string $fname Caller name
- * @throws DBExpectedError
- * @since 1.23
- */
- public function rollbackMasterChanges( $fname = __METHOD__ ) {
- $restore = ( $this->trxRoundId !== false );
- $this->trxRoundId = false;
- $this->forEachOpenMasterConnection(
- function ( IDatabase $conn ) use ( $fname, $restore ) {
- if ( $conn->writesOrCallbacksPending() ) {
- $conn->rollback( $fname, $conn::FLUSHING_ALL_PEERS );
- }
- if ( $restore ) {
- $this->undoTransactionRoundFlags( $conn );
- }
- }
- );
- }
-
- /**
- * Suppress all pending post-COMMIT/ROLLBACK callbacks
- * @return Exception|null The first exception or null if there were none
- * @since 1.28
- */
- public function suppressTransactionEndCallbacks() {
- $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) {
- $conn->setTrxEndCallbackSuppression( true );
- } );
- }
-
- /**
- * @param IDatabase $conn
- */
- private function applyTransactionRoundFlags( IDatabase $conn ) {
- if ( $conn->getFlag( DBO_DEFAULT ) ) {
- // DBO_TRX is controlled entirely by CLI mode presence with DBO_DEFAULT.
- // Force DBO_TRX even in CLI mode since a commit round is expected soon.
- $conn->setFlag( DBO_TRX, $conn::REMEMBER_PRIOR );
- // If config has explicitly requested DBO_TRX be either on or off by not
- // setting DBO_DEFAULT, then respect that. Forcing no transactions is useful
- // for things like blob stores (ExternalStore) which want auto-commit mode.
- }
- }
-
- /**
- * @param IDatabase $conn
- */
- private function undoTransactionRoundFlags( IDatabase $conn ) {
- if ( $conn->getFlag( DBO_DEFAULT ) ) {
- $conn->restoreFlags( $conn::RESTORE_PRIOR );
- }
- }
-
- /**
- * Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot
- *
- * @param string $fname Caller name
- * @since 1.28
- */
- public function flushReplicaSnapshots( $fname = __METHOD__ ) {
- $this->forEachOpenReplicaConnection( function ( IDatabase $conn ) {
- $conn->flushSnapshot( __METHOD__ );
- } );
- }
-
- /**
- * @return bool Whether a master connection is already open
- * @since 1.24
- */
- public function hasMasterConnection() {
- return $this->isOpen( $this->getWriterIndex() );
- }
-
- /**
- * Determine if there are pending changes in a transaction by this thread
- * @since 1.23
- * @return bool
- */
- public function hasMasterChanges() {
- $pending = 0;
- $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$pending ) {
- $pending |= $conn->writesOrCallbacksPending();
- } );
-
- return (bool)$pending;
- }
-
- /**
- * Get the timestamp of the latest write query done by this thread
- * @since 1.25
- * @return float|bool UNIX timestamp or false
- */
- public function lastMasterChangeTimestamp() {
- $lastTime = false;
- $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$lastTime ) {
- $lastTime = max( $lastTime, $conn->lastDoneWrites() );
- } );
-
- return $lastTime;
- }
-
- /**
- * Check if this load balancer object had any recent or still
- * pending writes issued against it by this PHP thread
- *
- * @param float $age How many seconds ago is "recent" [defaults to mWaitTimeout]
- * @return bool
- * @since 1.25
- */
- public function hasOrMadeRecentMasterChanges( $age = null ) {
- $age = ( $age === null ) ? $this->mWaitTimeout : $age;
-
- return ( $this->hasMasterChanges()
- || $this->lastMasterChangeTimestamp() > microtime( true ) - $age );
- }
-
- /**
- * Get the list of callers that have pending master changes
- *
- * @return string[] List of method names
- * @since 1.27
- */
- public function pendingMasterChangeCallers() {
- $fnames = [];
- $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$fnames ) {
- $fnames = array_merge( $fnames, $conn->pendingWriteCallers() );
- } );
-
- return $fnames;
- }
-
- public function getLaggedReplicaMode( $domain = false ) {
- // No-op if there is only one DB (also avoids recursion)
- if ( !$this->laggedReplicaMode && $this->getServerCount() > 1 ) {
- try {
- // See if laggedReplicaMode gets set
- $conn = $this->getConnection( DB_REPLICA, false, $domain );
- $this->reuseConnection( $conn );
- } catch ( DBConnectionError $e ) {
- // Avoid expensive re-connect attempts and failures
- $this->allReplicasDownMode = true;
- $this->laggedReplicaMode = true;
- }
- }
-
- return $this->laggedReplicaMode;
- }
-
- /**
- * @param bool $domain
- * @return bool
- * @deprecated 1.28; use getLaggedReplicaMode()
- */
- public function getLaggedSlaveMode( $domain = false ) {
- return $this->getLaggedReplicaMode( $domain );
- }
-
- /**
- * @note This method will never cause a new DB connection
- * @return bool Whether any generic connection used for reads was highly "lagged"
- * @since 1.28
- */
- public function laggedReplicaUsed() {
- return $this->laggedReplicaMode;
- }
-
- /**
- * @return bool
- * @since 1.27
- * @deprecated Since 1.28; use laggedReplicaUsed()
- */
- public function laggedSlaveUsed() {
- return $this->laggedReplicaUsed();
- }
-
- /**
- * @note This method may trigger a DB connection if not yet done
- * @param string|bool $domain Domain ID, or false for the current domain
- * @param IDatabase|null DB master connection; used to avoid loops [optional]
- * @return string|bool Reason the master is read-only or false if it is not
- * @since 1.27
- */
- public function getReadOnlyReason( $domain = false, IDatabase $conn = null ) {
- if ( $this->readOnlyReason !== false ) {
- return $this->readOnlyReason;
- } elseif ( $this->getLaggedReplicaMode( $domain ) ) {
- if ( $this->allReplicasDownMode ) {
- return 'The database has been automatically locked ' .
- 'until the replica database servers become available';
- } else {
- return 'The database has been automatically locked ' .
- 'while the replica database servers catch up to the master.';
- }
- } elseif ( $this->masterRunningReadOnly( $domain, $conn ) ) {
- return 'The database master is running in read-only mode.';
- }
-
- return false;
- }
-
- /**
- * @param string $domain Domain ID, or false for the current domain
- * @param IDatabase|null DB master connectionl used to avoid loops [optional]
- * @return bool
- */
- private function masterRunningReadOnly( $domain, IDatabase $conn = null ) {
- $cache = $this->wanCache;
- $masterServer = $this->getServerName( $this->getWriterIndex() );
-
- return (bool)$cache->getWithSetCallback(
- $cache->makeGlobalKey( __CLASS__, 'server-read-only', $masterServer ),
- self::TTL_CACHE_READONLY,
- function () use ( $domain, $conn ) {
- $this->trxProfiler->setSilenced( true );
- try {
- $dbw = $conn ?: $this->getConnection( DB_MASTER, [], $domain );
- $readOnly = (int)$dbw->serverIsReadOnly();
- } catch ( DBError $e ) {
- $readOnly = 0;
- }
- $this->trxProfiler->setSilenced( false );
- return $readOnly;
- },
- [ 'pcTTL' => $cache::TTL_PROC_LONG, 'busyValue' => 0 ]
- );
- }
-
- public function allowLagged( $mode = null ) {
- if ( $mode === null ) {
- return $this->mAllowLagged;
- }
- $this->mAllowLagged = $mode;
-
- return $this->mAllowLagged;
- }
-
- public function pingAll() {
- $success = true;
- $this->forEachOpenConnection( function ( IDatabase $conn ) use ( &$success ) {
- if ( !$conn->ping() ) {
- $success = false;
- }
- } );
-
- return $success;
- }
-
- public function forEachOpenConnection( $callback, array $params = [] ) {
- foreach ( $this->mConns as $connsByServer ) {
- foreach ( $connsByServer as $serverConns ) {
- foreach ( $serverConns as $conn ) {
- $mergedParams = array_merge( [ $conn ], $params );
- call_user_func_array( $callback, $mergedParams );
- }
- }
- }
- }
-
- /**
- * Call a function with each open connection object to a master
- * @param callable $callback
- * @param array $params
- * @since 1.28
- */
- public function forEachOpenMasterConnection( $callback, array $params = [] ) {
- $masterIndex = $this->getWriterIndex();
- foreach ( $this->mConns as $connsByServer ) {
- if ( isset( $connsByServer[$masterIndex] ) ) {
- /** @var IDatabase $conn */
- foreach ( $connsByServer[$masterIndex] as $conn ) {
- $mergedParams = array_merge( [ $conn ], $params );
- call_user_func_array( $callback, $mergedParams );
- }
- }
- }
- }
-
- /**
- * Call a function with each open replica DB connection object
- * @param callable $callback
- * @param array $params
- * @since 1.28
- */
- public function forEachOpenReplicaConnection( $callback, array $params = [] ) {
- foreach ( $this->mConns as $connsByServer ) {
- foreach ( $connsByServer as $i => $serverConns ) {
- if ( $i === $this->getWriterIndex() ) {
- continue; // skip master
- }
- foreach ( $serverConns as $conn ) {
- $mergedParams = array_merge( [ $conn ], $params );
- call_user_func_array( $callback, $mergedParams );
- }
- }
- }
- }
-
- public function getMaxLag( $domain = false ) {
- $maxLag = -1;
- $host = '';
- $maxIndex = 0;
-
- if ( $this->getServerCount() <= 1 ) {
- return [ $host, $maxLag, $maxIndex ]; // no replication = no lag
- }
-
- $lagTimes = $this->getLagTimes( $domain );
- foreach ( $lagTimes as $i => $lag ) {
- if ( $this->mLoads[$i] > 0 && $lag > $maxLag ) {
- $maxLag = $lag;
- $host = $this->mServers[$i]['host'];
- $maxIndex = $i;
- }
- }
-
- return [ $host, $maxLag, $maxIndex ];
- }
-
- public function getLagTimes( $domain = false ) {
- if ( $this->getServerCount() <= 1 ) {
- return [ 0 => 0 ]; // no replication = no lag
- }
-
- # Send the request to the load monitor
- return $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $domain );
- }
-
- public function safeGetLag( IDatabase $conn ) {
- if ( $this->getServerCount() == 1 ) {
- return 0;
- } else {
- return $conn->getLag();
- }
- }
-
- /**
- * Wait for a replica DB to reach a specified master position
- *
- * This will connect to the master to get an accurate position if $pos is not given
- *
- * @param IDatabase $conn Replica DB
- * @param DBMasterPos|bool $pos Master position; default: current position
- * @param integer $timeout Timeout in seconds
- * @return bool Success
- * @since 1.27
- */
- public function safeWaitForMasterPos( IDatabase $conn, $pos = false, $timeout = 10 ) {
- if ( $this->getServerCount() == 1 || !$conn->getLBInfo( 'replica' ) ) {
- return true; // server is not a replica DB
- }
-
- $pos = $pos ?: $this->getConnection( DB_MASTER )->getMasterPos();
- if ( !( $pos instanceof DBMasterPos ) ) {
- return false; // something is misconfigured
- }
-
- $result = $conn->masterPosWait( $pos, $timeout );
- if ( $result == -1 || is_null( $result ) ) {
- $msg = __METHOD__ . ": Timed out waiting on {$conn->getServer()} pos {$pos}";
- $this->replLogger->warning( "$msg" );
- $ok = false;
- } else {
- $this->replLogger->info( __METHOD__ . ": Done" );
- $ok = true;
- }
-
- return $ok;
- }
-
- /**
- * Clear the cache for slag lag delay times
- *
- * This is only used for testing
- * @since 1.26
- */
- public function clearLagTimeCache() {
- $this->getLoadMonitor()->clearCaches();
- }
-
- /**
- * Set a callback via IDatabase::setTransactionListener() on
- * all current and future master connections of this load balancer
- *
- * @param string $name Callback name
- * @param callable|null $callback
- * @since 1.28
- */
- public function setTransactionListener( $name, callable $callback = null ) {
- if ( $callback ) {
- $this->trxRecurringCallbacks[$name] = $callback;
- } else {
- unset( $this->trxRecurringCallbacks[$name] );
- }
- $this->forEachOpenMasterConnection(
- function ( IDatabase $conn ) use ( $name, $callback ) {
- $conn->setTransactionListener( $name, $callback );
- }
- );
- }
-
- /**
- * Set a new table prefix for the existing local domain ID for testing
- *
- * @param string $prefix
- * @since 1.28
- */
- public function setDomainPrefix( $prefix ) {
- list( $dbName, ) = explode( '-', $this->localDomain, 2 );
-
- $this->localDomain = "{$dbName}-{$prefix}";
- }
-}
--- /dev/null
+<?php
+/**
+ * Database load balancing manager
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Database
+ */
+use Psr\Log\LoggerInterface;
+
+/**
+ * Database load balancing, tracking, and transaction management object
+ *
+ * @ingroup Database
+ */
+class LoadBalancer implements ILoadBalancer {
+ /** @var array[] Map of (server index => server config array) */
+ private $mServers;
+ /** @var array[] Map of (local/foreignUsed/foreignFree => server index => IDatabase array) */
+ private $mConns;
+ /** @var array Map of (server index => weight) */
+ private $mLoads;
+ /** @var array[] Map of (group => server index => weight) */
+ private $mGroupLoads;
+ /** @var bool Whether to disregard replica DB lag as a factor in replica DB selection */
+ private $mAllowLagged;
+ /** @var integer Seconds to spend waiting on replica DB lag to resolve */
+ private $mWaitTimeout;
+ /** @var string The LoadMonitor subclass name */
+ private $mLoadMonitorClass;
+
+ /** @var LoadMonitor */
+ private $mLoadMonitor;
+ /** @var BagOStuff */
+ private $srvCache;
+ /** @var BagOStuff */
+ private $memCache;
+ /** @var WANObjectCache */
+ private $wanCache;
+ /** @var TransactionProfiler */
+ protected $trxProfiler;
+ /** @var LoggerInterface */
+ protected $replLogger;
+ /** @var LoggerInterface */
+ protected $connLogger;
+ /** @var LoggerInterface */
+ protected $queryLogger;
+ /** @var LoggerInterface */
+ protected $perfLogger;
+
+ /** @var bool|IDatabase Database connection that caused a problem */
+ private $mErrorConnection;
+ /** @var integer The generic (not query grouped) replica DB index (of $mServers) */
+ private $mReadIndex;
+ /** @var bool|DBMasterPos False if not set */
+ private $mWaitForPos;
+ /** @var bool Whether the generic reader fell back to a lagged replica DB */
+ private $laggedReplicaMode = false;
+ /** @var bool Whether the generic reader fell back to a lagged replica DB */
+ private $allReplicasDownMode = false;
+ /** @var string The last DB selection or connection error */
+ private $mLastError = 'Unknown error';
+ /** @var string|bool Reason the LB is read-only or false if not */
+ private $readOnlyReason = false;
+ /** @var integer Total connections opened */
+ private $connsOpened = 0;
+ /** @var string|bool String if a requested DBO_TRX transaction round is active */
+ private $trxRoundId = false;
+ /** @var array[] Map of (name => callable) */
+ private $trxRecurringCallbacks = [];
+ /** @var string Local Domain ID and default for selectDB() calls */
+ private $localDomain;
+ /** @var string Current server name */
+ private $host;
+
+ /** @var callable Exception logger */
+ private $errorLogger;
+
+ /** @var boolean */
+ private $disabled = false;
+
+ /** @var integer Warn when this many connection are held */
+ const CONN_HELD_WARN_THRESHOLD = 10;
+ /** @var integer Default 'max lag' when unspecified */
+ const MAX_LAG_DEFAULT = 10;
+ /** @var integer Max time to wait for a replica DB to catch up (e.g. ChronologyProtector) */
+ const POS_WAIT_TIMEOUT = 10;
+ /** @var integer Seconds to cache master server read-only status */
+ const TTL_CACHE_READONLY = 5;
+
+ public function __construct( array $params ) {
+ if ( !isset( $params['servers'] ) ) {
+ throw new InvalidArgumentException( __CLASS__ . ': missing servers parameter' );
+ }
+ $this->mServers = $params['servers'];
+ $this->mWaitTimeout = isset( $params['waitTimeout'] )
+ ? $params['waitTimeout']
+ : self::POS_WAIT_TIMEOUT;
+ $this->localDomain = isset( $params['localDomain'] ) ? $params['localDomain'] : '';
+
+ $this->mReadIndex = -1;
+ $this->mConns = [
+ 'local' => [],
+ 'foreignUsed' => [],
+ 'foreignFree' => [] ];
+ $this->mLoads = [];
+ $this->mWaitForPos = false;
+ $this->mErrorConnection = false;
+ $this->mAllowLagged = false;
+
+ if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) {
+ $this->readOnlyReason = $params['readOnlyReason'];
+ }
+
+ if ( isset( $params['loadMonitor'] ) ) {
+ $this->mLoadMonitorClass = $params['loadMonitor'];
+ } else {
+ $master = reset( $params['servers'] );
+ if ( isset( $master['type'] ) && $master['type'] === 'mysql' ) {
+ $this->mLoadMonitorClass = 'LoadMonitorMySQL';
+ } else {
+ $this->mLoadMonitorClass = 'LoadMonitorNull';
+ }
+ }
+
+ 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] = [];
+ }
+ $this->mGroupLoads[$group][$i] = $ratio;
+ }
+ }
+ }
+
+ if ( isset( $params['srvCache'] ) ) {
+ $this->srvCache = $params['srvCache'];
+ } else {
+ $this->srvCache = new EmptyBagOStuff();
+ }
+ if ( isset( $params['memCache'] ) ) {
+ $this->memCache = $params['memCache'];
+ } else {
+ $this->memCache = new EmptyBagOStuff();
+ }
+ if ( isset( $params['wanCache'] ) ) {
+ $this->wanCache = $params['wanCache'];
+ } else {
+ $this->wanCache = WANObjectCache::newEmpty();
+ }
+ if ( isset( $params['trxProfiler'] ) ) {
+ $this->trxProfiler = $params['trxProfiler'];
+ } else {
+ $this->trxProfiler = new TransactionProfiler();
+ }
+
+ $this->errorLogger = isset( $params['errorLogger'] )
+ ? $params['errorLogger']
+ : function ( Exception $e ) {
+ trigger_error( E_WARNING, $e->getMessage() );
+ };
+
+ foreach ( [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ] as $key ) {
+ $this->$key = isset( $params[$key] ) ? $params[$key] : new \Psr\Log\NullLogger();
+ }
+
+ $this->host = isset( $params['hostname'] )
+ ? $params['hostname']
+ : ( gethostname() ?: 'unknown' );
+ }
+
+ /**
+ * Get a LoadMonitor instance
+ *
+ * @return LoadMonitor
+ */
+ private function getLoadMonitor() {
+ if ( !isset( $this->mLoadMonitor ) ) {
+ $class = $this->mLoadMonitorClass;
+ $this->mLoadMonitor = new $class( $this, $this->srvCache, $this->memCache );
+ $this->mLoadMonitor->setLogger( $this->replLogger );
+ }
+
+ return $this->mLoadMonitor;
+ }
+
+ /**
+ * @param array $loads
+ * @param bool|string $domain Domain to get non-lagged for
+ * @param int $maxLag Restrict the maximum allowed lag to this many seconds
+ * @return bool|int|string
+ */
+ private function getRandomNonLagged( array $loads, $domain = false, $maxLag = INF ) {
+ $lags = $this->getLagTimes( $domain );
+
+ # Unset excessively lagged servers
+ foreach ( $lags as $i => $lag ) {
+ if ( $i != 0 ) {
+ # How much lag this server nominally is allowed to have
+ $maxServerLag = isset( $this->mServers[$i]['max lag'] )
+ ? $this->mServers[$i]['max lag']
+ : self::MAX_LAG_DEFAULT; // default
+ # Constrain that futher by $maxLag argument
+ $maxServerLag = min( $maxServerLag, $maxLag );
+
+ $host = $this->getServerName( $i );
+ if ( $lag === false && !is_infinite( $maxServerLag ) ) {
+ $this->replLogger->error( "Server $host (#$i) is not replicating?" );
+ unset( $loads[$i] );
+ } elseif ( $lag > $maxServerLag ) {
+ $this->replLogger->warning( "Server $host (#$i) has >= $lag seconds of lag" );
+ unset( $loads[$i] );
+ }
+ }
+ }
+
+ # Find out if all the replica DBs 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 replica DBs with zero load
+ # Do NOT use the master
+ # Instead, this function will return false, triggering read-only mode,
+ # and a lagged replica DB will be used instead.
+ return false;
+ }
+
+ if ( count( $loads ) == 0 ) {
+ return false;
+ }
+
+ # Return a random representative of the remainder
+ return ArrayUtils::pickRandom( $loads );
+ }
+
+ public function getReaderIndex( $group = false, $domain = false ) {
+ if ( count( $this->mServers ) == 1 ) {
+ # Skip the load balancing if there's only one server
+ return $this->getWriterIndex();
+ } elseif ( $group === false && $this->mReadIndex >= 0 ) {
+ # Shortcut if generic reader exists already
+ return $this->mReadIndex;
+ }
+
+ # 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
+ $this->connLogger->info( __METHOD__ . ": no loads for group $group" );
+
+ return false;
+ }
+ } else {
+ $nonErrorLoads = $this->mLoads;
+ }
+
+ if ( !count( $nonErrorLoads ) ) {
+ throw new InvalidArgumentException( "Empty server array given to LoadBalancer" );
+ }
+
+ # Scale the configured load ratios according to the dynamic load if supported
+ $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $group, $domain );
+
+ $laggedReplicaMode = false;
+
+ # No server found yet
+ $i = false;
+ # First try quickly looking through the available servers for a server that
+ # meets our criteria
+ $currentLoads = $nonErrorLoads;
+ while ( count( $currentLoads ) ) {
+ if ( $this->mAllowLagged || $laggedReplicaMode ) {
+ $i = ArrayUtils::pickRandom( $currentLoads );
+ } else {
+ $i = false;
+ if ( $this->mWaitForPos && $this->mWaitForPos->asOfTime() ) {
+ # ChronologyProtecter causes mWaitForPos to be set via sessions.
+ # This triggers doWait() after connect, so it's especially good to
+ # avoid lagged servers so as to avoid just blocking in that method.
+ $ago = microtime( true ) - $this->mWaitForPos->asOfTime();
+ # Aim for <= 1 second of waiting (being too picky can backfire)
+ $i = $this->getRandomNonLagged( $currentLoads, $domain, $ago + 1 );
+ }
+ if ( $i === false ) {
+ # Any server with less lag than it's 'max lag' param is preferable
+ $i = $this->getRandomNonLagged( $currentLoads, $domain );
+ }
+ if ( $i === false && count( $currentLoads ) != 0 ) {
+ # All replica DBs lagged. Switch to read-only mode
+ $this->replLogger->error( "All replica DBs lagged. Switch to read-only mode" );
+ $i = ArrayUtils::pickRandom( $currentLoads );
+ $laggedReplicaMode = true;
+ }
+ }
+
+ if ( $i === false ) {
+ # pickRandom() returned false
+ # This is permanent and means the configuration or the load monitor
+ # wants us to return false.
+ $this->connLogger->debug( __METHOD__ . ": pickRandom() returned false" );
+
+ return false;
+ }
+
+ $serverName = $this->getServerName( $i );
+ $this->connLogger->debug( __METHOD__ . ": Using reader #$i: $serverName..." );
+
+ $conn = $this->openConnection( $i, $domain );
+ if ( !$conn ) {
+ $this->connLogger->warning( __METHOD__ . ": Failed connecting to $i/$domain" );
+ unset( $nonErrorLoads[$i] );
+ unset( $currentLoads[$i] );
+ $i = false;
+ continue;
+ }
+
+ // Decrement reference counter, we are finished with this connection.
+ // It will be incremented for the caller later.
+ if ( $domain !== false ) {
+ $this->reuseConnection( $conn );
+ }
+
+ # Return this server
+ break;
+ }
+
+ # If all servers were down, quit now
+ if ( !count( $nonErrorLoads ) ) {
+ $this->connLogger->error( "All servers down" );
+ }
+
+ if ( $i !== false ) {
+ # Replica DB connection successful.
+ # Wait for the session master pos for a short time.
+ if ( $this->mWaitForPos && $i > 0 ) {
+ $this->doWait( $i );
+ }
+ if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $group === false ) {
+ $this->mReadIndex = $i;
+ # Record if the generic reader index is in "lagged replica DB" mode
+ if ( $laggedReplicaMode ) {
+ $this->laggedReplicaMode = true;
+ }
+ }
+ $serverName = $this->getServerName( $i );
+ $this->connLogger->debug(
+ __METHOD__ . ": using server $serverName for group '$group'" );
+ }
+
+ return $i;
+ }
+
+ public function waitFor( $pos ) {
+ $this->mWaitForPos = $pos;
+ $i = $this->mReadIndex;
+
+ if ( $i > 0 ) {
+ if ( !$this->doWait( $i ) ) {
+ $this->laggedReplicaMode = true;
+ }
+ }
+ }
+
+ /**
+ * Set the master wait position and wait for a "generic" replica DB to catch up to it
+ *
+ * This can be used a faster proxy for waitForAll()
+ *
+ * @param DBMasterPos $pos
+ * @param int $timeout Max seconds to wait; default is mWaitTimeout
+ * @return bool Success (able to connect and no timeouts reached)
+ * @since 1.26
+ */
+ public function waitForOne( $pos, $timeout = null ) {
+ $this->mWaitForPos = $pos;
+
+ $i = $this->mReadIndex;
+ if ( $i <= 0 ) {
+ // Pick a generic replica DB if there isn't one yet
+ $readLoads = $this->mLoads;
+ unset( $readLoads[$this->getWriterIndex()] ); // replica DBs only
+ $readLoads = array_filter( $readLoads ); // with non-zero load
+ $i = ArrayUtils::pickRandom( $readLoads );
+ }
+
+ if ( $i > 0 ) {
+ $ok = $this->doWait( $i, true, $timeout );
+ } else {
+ $ok = true; // no applicable loads
+ }
+
+ return $ok;
+ }
+
+ public function waitForAll( $pos, $timeout = null ) {
+ $this->mWaitForPos = $pos;
+ $serverCount = count( $this->mServers );
+
+ $ok = true;
+ for ( $i = 1; $i < $serverCount; $i++ ) {
+ if ( $this->mLoads[$i] > 0 ) {
+ $ok = $this->doWait( $i, true, $timeout ) && $ok;
+ }
+ }
+
+ return $ok;
+ }
+
+ public function getAnyOpenConnection( $i ) {
+ foreach ( $this->mConns as $connsByServer ) {
+ if ( !empty( $connsByServer[$i] ) ) {
+ return reset( $connsByServer[$i] );
+ }
+ }
+
+ return false;
+ }
+
+ /**
+ * Wait for a given replica DB to catch up to the master pos stored in $this
+ * @param int $index Server index
+ * @param bool $open Check the server even if a new connection has to be made
+ * @param int $timeout Max seconds to wait; default is mWaitTimeout
+ * @return bool
+ */
+ protected function doWait( $index, $open = false, $timeout = null ) {
+ $close = false; // close the connection afterwards
+
+ // Check if we already know that the DB has reached this point
+ $server = $this->getServerName( $index );
+ $key = $this->srvCache->makeGlobalKey( __CLASS__, 'last-known-pos', $server );
+ /** @var DBMasterPos $knownReachedPos */
+ $knownReachedPos = $this->srvCache->get( $key );
+ if ( $knownReachedPos && $knownReachedPos->hasReached( $this->mWaitForPos ) ) {
+ $this->replLogger->debug( __METHOD__ .
+ ": replica DB $server known to be caught up (pos >= $knownReachedPos)." );
+ return true;
+ }
+
+ // Find a connection to wait on, creating one if needed and allowed
+ $conn = $this->getAnyOpenConnection( $index );
+ if ( !$conn ) {
+ if ( !$open ) {
+ $this->replLogger->debug( __METHOD__ . ": no connection open for $server" );
+
+ return false;
+ } else {
+ $conn = $this->openConnection( $index, '' );
+ if ( !$conn ) {
+ $this->replLogger->warning( __METHOD__ . ": failed to connect to $server" );
+
+ return false;
+ }
+ // Avoid connection spam in waitForAll() when connections
+ // are made just for the sake of doing this lag check.
+ $close = true;
+ }
+ }
+
+ $this->replLogger->info( __METHOD__ . ": Waiting for replica DB $server to catch up..." );
+ $timeout = $timeout ?: $this->mWaitTimeout;
+ $result = $conn->masterPosWait( $this->mWaitForPos, $timeout );
+
+ if ( $result == -1 || is_null( $result ) ) {
+ // Timed out waiting for replica DB, use master instead
+ $msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
+ $this->replLogger->warning( "$msg" );
+ $ok = false;
+ } else {
+ $this->replLogger->info( __METHOD__ . ": Done" );
+ $ok = true;
+ // Remember that the DB reached this point
+ $this->srvCache->set( $key, $this->mWaitForPos, BagOStuff::TTL_DAY );
+ }
+
+ if ( $close ) {
+ $this->closeConnection( $conn );
+ }
+
+ return $ok;
+ }
+
+ public function getConnection( $i, $groups = [], $domain = false ) {
+ if ( $i === null || $i === false ) {
+ throw new InvalidArgumentException( 'Attempt to call ' . __METHOD__ .
+ ' with invalid server index' );
+ }
+
+ if ( $domain === $this->localDomain ) {
+ $domain = false;
+ }
+
+ $groups = ( $groups === false || $groups === [] )
+ ? [ false ] // check one "group": the generic pool
+ : (array)$groups;
+
+ $masterOnly = ( $i == DB_MASTER || $i == $this->getWriterIndex() );
+ $oldConnsOpened = $this->connsOpened; // connections open now
+
+ if ( $i == DB_MASTER ) {
+ $i = $this->getWriterIndex();
+ } else {
+ # Try to find an available server in any the query groups (in order)
+ foreach ( $groups as $group ) {
+ $groupIndex = $this->getReaderIndex( $group, $domain );
+ if ( $groupIndex !== false ) {
+ $i = $groupIndex;
+ break;
+ }
+ }
+ }
+
+ # Operation-based index
+ if ( $i == DB_REPLICA ) {
+ $this->mLastError = 'Unknown error'; // reset error string
+ # Try the general server pool if $groups are unavailable.
+ $i = in_array( false, $groups, true )
+ ? false // don't bother with this if that is what was tried above
+ : $this->getReaderIndex( false, $domain );
+ # Couldn't find a working server in getReaderIndex()?
+ if ( $i === false ) {
+ $this->mLastError = 'No working replica DB server: ' . $this->mLastError;
+
+ return $this->reportConnectionError();
+ }
+ }
+
+ # Now we have an explicit index into the servers array
+ $conn = $this->openConnection( $i, $domain );
+ if ( !$conn ) {
+ return $this->reportConnectionError();
+ }
+
+ # Profile any new connections that happen
+ if ( $this->connsOpened > $oldConnsOpened ) {
+ $host = $conn->getServer();
+ $dbname = $conn->getDBname();
+ $this->trxProfiler->recordConnection( $host, $dbname, $masterOnly );
+ }
+
+ if ( $masterOnly ) {
+ # Make master-requested DB handles inherit any read-only mode setting
+ $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $domain, $conn ) );
+ }
+
+ return $conn;
+ }
+
+ public function reuseConnection( $conn ) {
+ $serverIndex = $conn->getLBInfo( 'serverIndex' );
+ $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
+ if ( $serverIndex === null || $refCount === null ) {
+ /**
+ * This can happen in code like:
+ * foreach ( $dbs as $db ) {
+ * $conn = $lb->getConnection( DB_REPLICA, [], $db );
+ * ...
+ * $lb->reuseConnection( $conn );
+ * }
+ * When a connection to the local DB is opened in this way, reuseConnection()
+ * should be ignored
+ */
+ return;
+ }
+
+ $dbName = $conn->getDBname();
+ $prefix = $conn->tablePrefix();
+ if ( strval( $prefix ) !== '' ) {
+ $domain = "$dbName-$prefix";
+ } else {
+ $domain = $dbName;
+ }
+ if ( $this->mConns['foreignUsed'][$serverIndex][$domain] !== $conn ) {
+ throw new InvalidArgumentException( __METHOD__ . ": connection not found, has " .
+ "the connection been freed already?" );
+ }
+ $conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
+ if ( $refCount <= 0 ) {
+ $this->mConns['foreignFree'][$serverIndex][$domain] = $conn;
+ unset( $this->mConns['foreignUsed'][$serverIndex][$domain] );
+ $this->connLogger->debug( __METHOD__ . ": freed connection $serverIndex/$domain" );
+ } else {
+ $this->connLogger->debug( __METHOD__ .
+ ": reference count for $serverIndex/$domain reduced to $refCount" );
+ }
+ }
+
+ /**
+ * Get a database connection handle reference
+ *
+ * The handle's methods wrap simply wrap those of a IDatabase handle
+ *
+ * @see LoadBalancer::getConnection() for parameter information
+ *
+ * @param int $db
+ * @param array|string|bool $groups Query group(s), or false for the generic reader
+ * @param string|bool $domain Domain ID, or false for the current domain
+ * @return DBConnRef
+ * @since 1.22
+ */
+ public function getConnectionRef( $db, $groups = [], $domain = false ) {
+ return new DBConnRef( $this, $this->getConnection( $db, $groups, $domain ) );
+ }
+
+ /**
+ * Get a database connection handle reference without connecting yet
+ *
+ * The handle's methods wrap simply wrap those of a IDatabase handle
+ *
+ * @see LoadBalancer::getConnection() for parameter information
+ *
+ * @param int $db
+ * @param array|string|bool $groups Query group(s), or false for the generic reader
+ * @param string|bool $domain Domain ID, or false for the current domain
+ * @return DBConnRef
+ * @since 1.22
+ */
+ public function getLazyConnectionRef( $db, $groups = [], $domain = false ) {
+ $domain = ( $domain !== false ) ? $domain : $this->localDomain;
+
+ return new DBConnRef( $this, [ $db, $groups, $domain ] );
+ }
+
+ public function openConnection( $i, $domain = false ) {
+ if ( $domain !== false ) {
+ $conn = $this->openForeignConnection( $i, $domain );
+ } elseif ( 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 );
+ $serverName = $this->getServerName( $i );
+ if ( $conn->isOpen() ) {
+ $this->connLogger->debug( "Connected to database $i at '$serverName'." );
+ $this->mConns['local'][$i][0] = $conn;
+ } else {
+ $this->connLogger->warning( "Failed to connect to database $i at '$serverName'." );
+ $this->mErrorConnection = $conn;
+ $conn = false;
+ }
+ }
+
+ if ( $conn && !$conn->isOpen() ) {
+ // Connection was made but later unrecoverably lost for some reason.
+ // Do not return a handle that will just throw exceptions on use,
+ // but let the calling code (e.g. getReaderIndex) try another server.
+ // See DatabaseMyslBase::ping() for how this can happen.
+ $this->mErrorConnection = $conn;
+ $conn = false;
+ }
+
+ 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 domain. 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.
+ *
+ * @note If disable() was called on this LoadBalancer, this method will throw a DBAccessError.
+ *
+ * @param int $i Server index
+ * @param string $domain Domain ID to open
+ * @return IDatabase
+ */
+ private function openForeignConnection( $i, $domain ) {
+ list( $dbName, $prefix ) = explode( '-', $domain, 2 ) + [ '', '' ];
+
+ if ( isset( $this->mConns['foreignUsed'][$i][$domain] ) ) {
+ // Reuse an already-used connection
+ $conn = $this->mConns['foreignUsed'][$i][$domain];
+ $this->connLogger->debug( __METHOD__ . ": reusing connection $i/$domain" );
+ } elseif ( isset( $this->mConns['foreignFree'][$i][$domain] ) ) {
+ // Reuse a free connection for the same domain
+ $conn = $this->mConns['foreignFree'][$i][$domain];
+ unset( $this->mConns['foreignFree'][$i][$domain] );
+ $this->mConns['foreignUsed'][$i][$domain] = $conn;
+ $this->connLogger->debug( __METHOD__ . ": reusing free connection $i/$domain" );
+ } elseif ( !empty( $this->mConns['foreignFree'][$i] ) ) {
+ // Reuse a connection from another domain
+ $conn = reset( $this->mConns['foreignFree'][$i] );
+ $oldDomain = key( $this->mConns['foreignFree'][$i] );
+
+ // The empty string as a DB name means "don't care".
+ // DatabaseMysqlBase::open() already handle this on connection.
+ if ( $dbName !== '' && !$conn->selectDB( $dbName ) ) {
+ $this->mLastError = "Error selecting database $dbName on server " .
+ $conn->getServer() . " from client host {$this->host}";
+ $this->mErrorConnection = $conn;
+ $conn = false;
+ } else {
+ $conn->tablePrefix( $prefix );
+ unset( $this->mConns['foreignFree'][$i][$oldDomain] );
+ $this->mConns['foreignUsed'][$i][$domain] = $conn;
+ $this->connLogger->debug( __METHOD__ .
+ ": reusing free connection from $oldDomain for $domain" );
+ }
+ } 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() ) {
+ $this->connLogger->warning( __METHOD__ . ": connection error for $i/$domain" );
+ $this->mErrorConnection = $conn;
+ $conn = false;
+ } else {
+ $conn->tablePrefix( $prefix );
+ $this->mConns['foreignUsed'][$i][$domain] = $conn;
+ $this->connLogger->debug( __METHOD__ . ": opened new connection for $i/$domain" );
+ }
+ }
+
+ // Increment reference count
+ if ( $conn ) {
+ $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
+ $conn->setLBInfo( 'foreignPoolRefCount', $refCount + 1 );
+ }
+
+ return $conn;
+ }
+
+ /**
+ * Test if the specified index represents an open connection
+ *
+ * @param int $index Server index
+ * @access private
+ * @return bool
+ */
+ 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
+ *
+ * @param array $server
+ * @param bool $dbNameOverride
+ * @return IDatabase
+ * @throws DBAccessError
+ * @throws MWException
+ */
+ protected function reallyOpenConnection( $server, $dbNameOverride = false ) {
+ if ( $this->disabled ) {
+ throw new DBAccessError();
+ }
+
+ if ( !is_array( $server ) ) {
+ throw new InvalidArgumentException(
+ 'You must update your load-balancing configuration. ' .
+ 'See DefaultSettings.php entry for $wgDBservers.' );
+ }
+
+ if ( $dbNameOverride !== false ) {
+ $server['dbname'] = $dbNameOverride;
+ }
+
+ // Let the handle know what the cluster master is (e.g. "db1052")
+ $masterName = $this->getServerName( $this->getWriterIndex() );
+ $server['clusterMasterHost'] = $masterName;
+
+ // Log when many connection are made on requests
+ if ( ++$this->connsOpened >= self::CONN_HELD_WARN_THRESHOLD ) {
+ $this->perfLogger->warning( __METHOD__ . ": " .
+ "{$this->connsOpened}+ connections made (master=$masterName)" );
+ }
+
+ // Set loggers
+ $server['connLogger'] = $this->connLogger;
+ $server['queryLogger'] = $this->queryLogger;
+ $server['trxProfiler'] = $this->trxProfiler;
+
+ // Create a live connection 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 );
+ $db->setLazyMasterHandle(
+ $this->getLazyConnectionRef( DB_MASTER, [], $db->getWikiID() )
+ );
+
+ if ( $server['serverIndex'] === $this->getWriterIndex() ) {
+ if ( $this->trxRoundId !== false ) {
+ $this->applyTransactionRoundFlags( $db );
+ }
+ foreach ( $this->trxRecurringCallbacks as $name => $callback ) {
+ $db->setTransactionListener( $name, $callback );
+ }
+ }
+
+ return $db;
+ }
+
+ /**
+ * @throws DBConnectionError
+ * @return bool
+ */
+ private function reportConnectionError() {
+ $conn = $this->mErrorConnection; // The connection which caused the error
+ $context = [
+ 'method' => __METHOD__,
+ 'last_error' => $this->mLastError,
+ ];
+
+ if ( !is_object( $conn ) ) {
+ // No last connection, probably due to all servers being too busy
+ $this->connLogger->error(
+ "LB failure with no last connection. Connection error: {last_error}",
+ $context
+ );
+
+ // If all servers were busy, mLastError will contain something sensible
+ throw new DBConnectionError( null, $this->mLastError );
+ } else {
+ $context['db_server'] = $conn->getProperty( 'mServer' );
+ $this->connLogger->warning(
+ "Connection error: {last_error} ({db_server})",
+ $context
+ );
+
+ // throws DBConnectionError
+ $conn->reportConnectionError( "{$this->mLastError} ({$context['db_server']})" );
+ }
+
+ return false; /* not reached */
+ }
+
+ public function getWriterIndex() {
+ return 0;
+ }
+
+ public function haveIndex( $i ) {
+ return array_key_exists( $i, $this->mServers );
+ }
+
+ public function isNonZeroLoad( $i ) {
+ return array_key_exists( $i, $this->mServers ) && $this->mLoads[$i] != 0;
+ }
+
+ public function getServerCount() {
+ return count( $this->mServers );
+ }
+
+ public function getServerName( $i ) {
+ if ( isset( $this->mServers[$i]['hostName'] ) ) {
+ $name = $this->mServers[$i]['hostName'];
+ } elseif ( isset( $this->mServers[$i]['host'] ) ) {
+ $name = $this->mServers[$i]['host'];
+ } else {
+ $name = '';
+ }
+
+ return ( $name != '' ) ? $name : 'localhost';
+ }
+
+ public function getServerInfo( $i ) {
+ if ( isset( $this->mServers[$i] ) ) {
+ return $this->mServers[$i];
+ } else {
+ return false;
+ }
+ }
+
+ public function setServerInfo( $i, array $serverInfo ) {
+ $this->mServers[$i] = $serverInfo;
+ }
+
+ public function getMasterPos() {
+ # If this entire request was served from a replica DB without opening a connection to the
+ # master (however unlikely that may be), then we can fetch the position from the replica DB.
+ $masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
+ if ( !$masterConn ) {
+ $serverCount = count( $this->mServers );
+ for ( $i = 1; $i < $serverCount; $i++ ) {
+ $conn = $this->getAnyOpenConnection( $i );
+ if ( $conn ) {
+ return $conn->getSlavePos();
+ }
+ }
+ } else {
+ return $masterConn->getMasterPos();
+ }
+
+ return false;
+ }
+
+ /**
+ * Disable this load balancer. All connections are closed, and any attempt to
+ * open a new connection will result in a DBAccessError.
+ *
+ * @since 1.27
+ */
+ public function disable() {
+ $this->closeAll();
+ $this->disabled = true;
+ }
+
+ public function closeAll() {
+ $this->forEachOpenConnection( function ( IDatabase $conn ) {
+ $conn->close();
+ } );
+
+ $this->mConns = [
+ 'local' => [],
+ 'foreignFree' => [],
+ 'foreignUsed' => [],
+ ];
+ $this->connsOpened = 0;
+ }
+
+ public function closeConnection( IDatabase $conn ) {
+ $serverIndex = $conn->getLBInfo( 'serverIndex' ); // second index level of mConns
+ foreach ( $this->mConns as $type => $connsByServer ) {
+ if ( !isset( $connsByServer[$serverIndex] ) ) {
+ continue;
+ }
+
+ foreach ( $connsByServer[$serverIndex] as $i => $trackedConn ) {
+ if ( $conn === $trackedConn ) {
+ unset( $this->mConns[$type][$serverIndex][$i] );
+ --$this->connsOpened;
+ break 2;
+ }
+ }
+ }
+
+ $conn->close();
+ }
+
+ public function commitAll( $fname = __METHOD__ ) {
+ $failures = [];
+
+ $restore = ( $this->trxRoundId !== false );
+ $this->trxRoundId = false;
+ $this->forEachOpenConnection(
+ function ( IDatabase $conn ) use ( $fname, $restore, &$failures ) {
+ try {
+ $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS );
+ } catch ( DBError $e ) {
+ call_user_func( $this->errorLogger, $e );
+ $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
+ }
+ if ( $restore && $conn->getLBInfo( 'master' ) ) {
+ $this->undoTransactionRoundFlags( $conn );
+ }
+ }
+ );
+
+ if ( $failures ) {
+ throw new DBExpectedError(
+ null,
+ "Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
+ );
+ }
+ }
+
+ /**
+ * Perform all pre-commit callbacks that remain part of the atomic transactions
+ * and disable any post-commit callbacks until runMasterPostTrxCallbacks()
+ * @since 1.28
+ */
+ public function finalizeMasterChanges() {
+ $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) {
+ // Any error should cause all DB transactions to be rolled back together
+ $conn->setTrxEndCallbackSuppression( false );
+ $conn->runOnTransactionPreCommitCallbacks();
+ // Defer post-commit callbacks until COMMIT finishes for all DBs
+ $conn->setTrxEndCallbackSuppression( true );
+ } );
+ }
+
+ /**
+ * Perform all pre-commit checks for things like replication safety
+ * @param array $options Includes:
+ * - maxWriteDuration : max write query duration time in seconds
+ * @throws DBTransactionError
+ * @since 1.28
+ */
+ public function approveMasterChanges( array $options ) {
+ $limit = isset( $options['maxWriteDuration'] ) ? $options['maxWriteDuration'] : 0;
+ $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( $limit ) {
+ // If atomic sections or explicit transactions are still open, some caller must have
+ // caught an exception but failed to properly rollback any changes. Detect that and
+ // throw and error (causing rollback).
+ if ( $conn->explicitTrxActive() ) {
+ throw new DBTransactionError(
+ $conn,
+ "Explicit transaction still active. A caller may have caught an error."
+ );
+ }
+ // Assert that the time to replicate the transaction will be sane.
+ // If this fails, then all DB transactions will be rollback back together.
+ $time = $conn->pendingWriteQueryDuration( $conn::ESTIMATE_DB_APPLY );
+ if ( $limit > 0 && $time > $limit ) {
+ throw new DBTransactionSizeError(
+ $conn,
+ "Transaction spent $time second(s) in writes, exceeding the $limit limit.",
+ [ $time, $limit ]
+ );
+ }
+ // If a connection sits idle while slow queries execute on another, that connection
+ // may end up dropped before the commit round is reached. Ping servers to detect this.
+ if ( $conn->writesOrCallbacksPending() && !$conn->ping() ) {
+ throw new DBTransactionError(
+ $conn,
+ "A connection to the {$conn->getDBname()} database was lost before commit."
+ );
+ }
+ } );
+ }
+
+ /**
+ * Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set)
+ *
+ * The DBO_TRX setting will be reverted to the default in each of these methods:
+ * - commitMasterChanges()
+ * - rollbackMasterChanges()
+ * - commitAll()
+ * This allows for custom transaction rounds from any outer transaction scope.
+ *
+ * @param string $fname
+ * @throws DBExpectedError
+ * @since 1.28
+ */
+ public function beginMasterChanges( $fname = __METHOD__ ) {
+ if ( $this->trxRoundId !== false ) {
+ throw new DBTransactionError(
+ null,
+ "$fname: Transaction round '{$this->trxRoundId}' already started."
+ );
+ }
+ $this->trxRoundId = $fname;
+
+ $failures = [];
+ $this->forEachOpenMasterConnection(
+ function ( DatabaseBase $conn ) use ( $fname, &$failures ) {
+ $conn->setTrxEndCallbackSuppression( true );
+ try {
+ $conn->flushSnapshot( $fname );
+ } catch ( DBError $e ) {
+ call_user_func( $this->errorLogger, $e );
+ $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
+ }
+ $conn->setTrxEndCallbackSuppression( false );
+ $this->applyTransactionRoundFlags( $conn );
+ }
+ );
+
+ if ( $failures ) {
+ throw new DBExpectedError(
+ null,
+ "$fname: Flush failed on server(s) " . implode( "\n", array_unique( $failures ) )
+ );
+ }
+ }
+
+ public function commitMasterChanges( $fname = __METHOD__ ) {
+ $failures = [];
+
+ $restore = ( $this->trxRoundId !== false );
+ $this->trxRoundId = false;
+ $this->forEachOpenMasterConnection(
+ function ( IDatabase $conn ) use ( $fname, $restore, &$failures ) {
+ try {
+ if ( $conn->writesOrCallbacksPending() ) {
+ $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS );
+ } elseif ( $restore ) {
+ $conn->flushSnapshot( $fname );
+ }
+ } catch ( DBError $e ) {
+ call_user_func( $this->errorLogger, $e );
+ $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
+ }
+ if ( $restore ) {
+ $this->undoTransactionRoundFlags( $conn );
+ }
+ }
+ );
+
+ if ( $failures ) {
+ throw new DBExpectedError(
+ null,
+ "$fname: Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
+ );
+ }
+ }
+
+ /**
+ * Issue all pending post-COMMIT/ROLLBACK callbacks
+ * @param integer $type IDatabase::TRIGGER_* constant
+ * @return Exception|null The first exception or null if there were none
+ * @since 1.28
+ */
+ public function runMasterPostTrxCallbacks( $type ) {
+ $e = null; // first exception
+ $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) use ( $type, &$e ) {
+ $conn->setTrxEndCallbackSuppression( false );
+ if ( $conn->writesOrCallbacksPending() ) {
+ // This happens if onTransactionIdle() callbacks leave callbacks on *another* DB
+ // (which finished its callbacks already). Warn and recover in this case. Let the
+ // callbacks run in the final commitMasterChanges() in LBFactory::shutdown().
+ $this->queryLogger->error( __METHOD__ . ": found writes/callbacks pending." );
+ return;
+ } elseif ( $conn->trxLevel() ) {
+ // This happens for single-DB setups where DB_REPLICA uses the master DB,
+ // thus leaving an implicit read-only transaction open at this point. It
+ // also happens if onTransactionIdle() callbacks leave implicit transactions
+ // open on *other* DBs (which is slightly improper). Let these COMMIT on the
+ // next call to commitMasterChanges(), possibly in LBFactory::shutdown().
+ return;
+ }
+ try {
+ $conn->runOnTransactionIdleCallbacks( $type );
+ } catch ( Exception $ex ) {
+ $e = $e ?: $ex;
+ }
+ try {
+ $conn->runTransactionListenerCallbacks( $type );
+ } catch ( Exception $ex ) {
+ $e = $e ?: $ex;
+ }
+ } );
+
+ return $e;
+ }
+
+ /**
+ * Issue ROLLBACK only on master, only if queries were done on connection
+ * @param string $fname Caller name
+ * @throws DBExpectedError
+ * @since 1.23
+ */
+ public function rollbackMasterChanges( $fname = __METHOD__ ) {
+ $restore = ( $this->trxRoundId !== false );
+ $this->trxRoundId = false;
+ $this->forEachOpenMasterConnection(
+ function ( IDatabase $conn ) use ( $fname, $restore ) {
+ if ( $conn->writesOrCallbacksPending() ) {
+ $conn->rollback( $fname, $conn::FLUSHING_ALL_PEERS );
+ }
+ if ( $restore ) {
+ $this->undoTransactionRoundFlags( $conn );
+ }
+ }
+ );
+ }
+
+ /**
+ * Suppress all pending post-COMMIT/ROLLBACK callbacks
+ * @return Exception|null The first exception or null if there were none
+ * @since 1.28
+ */
+ public function suppressTransactionEndCallbacks() {
+ $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) {
+ $conn->setTrxEndCallbackSuppression( true );
+ } );
+ }
+
+ /**
+ * @param IDatabase $conn
+ */
+ private function applyTransactionRoundFlags( IDatabase $conn ) {
+ if ( $conn->getFlag( DBO_DEFAULT ) ) {
+ // DBO_TRX is controlled entirely by CLI mode presence with DBO_DEFAULT.
+ // Force DBO_TRX even in CLI mode since a commit round is expected soon.
+ $conn->setFlag( DBO_TRX, $conn::REMEMBER_PRIOR );
+ // If config has explicitly requested DBO_TRX be either on or off by not
+ // setting DBO_DEFAULT, then respect that. Forcing no transactions is useful
+ // for things like blob stores (ExternalStore) which want auto-commit mode.
+ }
+ }
+
+ /**
+ * @param IDatabase $conn
+ */
+ private function undoTransactionRoundFlags( IDatabase $conn ) {
+ if ( $conn->getFlag( DBO_DEFAULT ) ) {
+ $conn->restoreFlags( $conn::RESTORE_PRIOR );
+ }
+ }
+
+ /**
+ * Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot
+ *
+ * @param string $fname Caller name
+ * @since 1.28
+ */
+ public function flushReplicaSnapshots( $fname = __METHOD__ ) {
+ $this->forEachOpenReplicaConnection( function ( IDatabase $conn ) {
+ $conn->flushSnapshot( __METHOD__ );
+ } );
+ }
+
+ /**
+ * @return bool Whether a master connection is already open
+ * @since 1.24
+ */
+ public function hasMasterConnection() {
+ return $this->isOpen( $this->getWriterIndex() );
+ }
+
+ /**
+ * Determine if there are pending changes in a transaction by this thread
+ * @since 1.23
+ * @return bool
+ */
+ public function hasMasterChanges() {
+ $pending = 0;
+ $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$pending ) {
+ $pending |= $conn->writesOrCallbacksPending();
+ } );
+
+ return (bool)$pending;
+ }
+
+ /**
+ * Get the timestamp of the latest write query done by this thread
+ * @since 1.25
+ * @return float|bool UNIX timestamp or false
+ */
+ public function lastMasterChangeTimestamp() {
+ $lastTime = false;
+ $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$lastTime ) {
+ $lastTime = max( $lastTime, $conn->lastDoneWrites() );
+ } );
+
+ return $lastTime;
+ }
+
+ /**
+ * Check if this load balancer object had any recent or still
+ * pending writes issued against it by this PHP thread
+ *
+ * @param float $age How many seconds ago is "recent" [defaults to mWaitTimeout]
+ * @return bool
+ * @since 1.25
+ */
+ public function hasOrMadeRecentMasterChanges( $age = null ) {
+ $age = ( $age === null ) ? $this->mWaitTimeout : $age;
+
+ return ( $this->hasMasterChanges()
+ || $this->lastMasterChangeTimestamp() > microtime( true ) - $age );
+ }
+
+ /**
+ * Get the list of callers that have pending master changes
+ *
+ * @return string[] List of method names
+ * @since 1.27
+ */
+ public function pendingMasterChangeCallers() {
+ $fnames = [];
+ $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$fnames ) {
+ $fnames = array_merge( $fnames, $conn->pendingWriteCallers() );
+ } );
+
+ return $fnames;
+ }
+
+ public function getLaggedReplicaMode( $domain = false ) {
+ // No-op if there is only one DB (also avoids recursion)
+ if ( !$this->laggedReplicaMode && $this->getServerCount() > 1 ) {
+ try {
+ // See if laggedReplicaMode gets set
+ $conn = $this->getConnection( DB_REPLICA, false, $domain );
+ $this->reuseConnection( $conn );
+ } catch ( DBConnectionError $e ) {
+ // Avoid expensive re-connect attempts and failures
+ $this->allReplicasDownMode = true;
+ $this->laggedReplicaMode = true;
+ }
+ }
+
+ return $this->laggedReplicaMode;
+ }
+
+ /**
+ * @param bool $domain
+ * @return bool
+ * @deprecated 1.28; use getLaggedReplicaMode()
+ */
+ public function getLaggedSlaveMode( $domain = false ) {
+ return $this->getLaggedReplicaMode( $domain );
+ }
+
+ /**
+ * @note This method will never cause a new DB connection
+ * @return bool Whether any generic connection used for reads was highly "lagged"
+ * @since 1.28
+ */
+ public function laggedReplicaUsed() {
+ return $this->laggedReplicaMode;
+ }
+
+ /**
+ * @return bool
+ * @since 1.27
+ * @deprecated Since 1.28; use laggedReplicaUsed()
+ */
+ public function laggedSlaveUsed() {
+ return $this->laggedReplicaUsed();
+ }
+
+ /**
+ * @note This method may trigger a DB connection if not yet done
+ * @param string|bool $domain Domain ID, or false for the current domain
+ * @param IDatabase|null DB master connection; used to avoid loops [optional]
+ * @return string|bool Reason the master is read-only or false if it is not
+ * @since 1.27
+ */
+ public function getReadOnlyReason( $domain = false, IDatabase $conn = null ) {
+ if ( $this->readOnlyReason !== false ) {
+ return $this->readOnlyReason;
+ } elseif ( $this->getLaggedReplicaMode( $domain ) ) {
+ if ( $this->allReplicasDownMode ) {
+ return 'The database has been automatically locked ' .
+ 'until the replica database servers become available';
+ } else {
+ return 'The database has been automatically locked ' .
+ 'while the replica database servers catch up to the master.';
+ }
+ } elseif ( $this->masterRunningReadOnly( $domain, $conn ) ) {
+ return 'The database master is running in read-only mode.';
+ }
+
+ return false;
+ }
+
+ /**
+ * @param string $domain Domain ID, or false for the current domain
+ * @param IDatabase|null DB master connectionl used to avoid loops [optional]
+ * @return bool
+ */
+ private function masterRunningReadOnly( $domain, IDatabase $conn = null ) {
+ $cache = $this->wanCache;
+ $masterServer = $this->getServerName( $this->getWriterIndex() );
+
+ return (bool)$cache->getWithSetCallback(
+ $cache->makeGlobalKey( __CLASS__, 'server-read-only', $masterServer ),
+ self::TTL_CACHE_READONLY,
+ function () use ( $domain, $conn ) {
+ $this->trxProfiler->setSilenced( true );
+ try {
+ $dbw = $conn ?: $this->getConnection( DB_MASTER, [], $domain );
+ $readOnly = (int)$dbw->serverIsReadOnly();
+ } catch ( DBError $e ) {
+ $readOnly = 0;
+ }
+ $this->trxProfiler->setSilenced( false );
+ return $readOnly;
+ },
+ [ 'pcTTL' => $cache::TTL_PROC_LONG, 'busyValue' => 0 ]
+ );
+ }
+
+ public function allowLagged( $mode = null ) {
+ if ( $mode === null ) {
+ return $this->mAllowLagged;
+ }
+ $this->mAllowLagged = $mode;
+
+ return $this->mAllowLagged;
+ }
+
+ public function pingAll() {
+ $success = true;
+ $this->forEachOpenConnection( function ( IDatabase $conn ) use ( &$success ) {
+ if ( !$conn->ping() ) {
+ $success = false;
+ }
+ } );
+
+ return $success;
+ }
+
+ public function forEachOpenConnection( $callback, array $params = [] ) {
+ foreach ( $this->mConns as $connsByServer ) {
+ foreach ( $connsByServer as $serverConns ) {
+ foreach ( $serverConns as $conn ) {
+ $mergedParams = array_merge( [ $conn ], $params );
+ call_user_func_array( $callback, $mergedParams );
+ }
+ }
+ }
+ }
+
+ /**
+ * Call a function with each open connection object to a master
+ * @param callable $callback
+ * @param array $params
+ * @since 1.28
+ */
+ public function forEachOpenMasterConnection( $callback, array $params = [] ) {
+ $masterIndex = $this->getWriterIndex();
+ foreach ( $this->mConns as $connsByServer ) {
+ if ( isset( $connsByServer[$masterIndex] ) ) {
+ /** @var IDatabase $conn */
+ foreach ( $connsByServer[$masterIndex] as $conn ) {
+ $mergedParams = array_merge( [ $conn ], $params );
+ call_user_func_array( $callback, $mergedParams );
+ }
+ }
+ }
+ }
+
+ /**
+ * Call a function with each open replica DB connection object
+ * @param callable $callback
+ * @param array $params
+ * @since 1.28
+ */
+ public function forEachOpenReplicaConnection( $callback, array $params = [] ) {
+ foreach ( $this->mConns as $connsByServer ) {
+ foreach ( $connsByServer as $i => $serverConns ) {
+ if ( $i === $this->getWriterIndex() ) {
+ continue; // skip master
+ }
+ foreach ( $serverConns as $conn ) {
+ $mergedParams = array_merge( [ $conn ], $params );
+ call_user_func_array( $callback, $mergedParams );
+ }
+ }
+ }
+ }
+
+ public function getMaxLag( $domain = false ) {
+ $maxLag = -1;
+ $host = '';
+ $maxIndex = 0;
+
+ if ( $this->getServerCount() <= 1 ) {
+ return [ $host, $maxLag, $maxIndex ]; // no replication = no lag
+ }
+
+ $lagTimes = $this->getLagTimes( $domain );
+ foreach ( $lagTimes as $i => $lag ) {
+ if ( $this->mLoads[$i] > 0 && $lag > $maxLag ) {
+ $maxLag = $lag;
+ $host = $this->mServers[$i]['host'];
+ $maxIndex = $i;
+ }
+ }
+
+ return [ $host, $maxLag, $maxIndex ];
+ }
+
+ public function getLagTimes( $domain = false ) {
+ if ( $this->getServerCount() <= 1 ) {
+ return [ 0 => 0 ]; // no replication = no lag
+ }
+
+ # Send the request to the load monitor
+ return $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $domain );
+ }
+
+ public function safeGetLag( IDatabase $conn ) {
+ if ( $this->getServerCount() == 1 ) {
+ return 0;
+ } else {
+ return $conn->getLag();
+ }
+ }
+
+ /**
+ * Wait for a replica DB to reach a specified master position
+ *
+ * This will connect to the master to get an accurate position if $pos is not given
+ *
+ * @param IDatabase $conn Replica DB
+ * @param DBMasterPos|bool $pos Master position; default: current position
+ * @param integer $timeout Timeout in seconds
+ * @return bool Success
+ * @since 1.27
+ */
+ public function safeWaitForMasterPos( IDatabase $conn, $pos = false, $timeout = 10 ) {
+ if ( $this->getServerCount() == 1 || !$conn->getLBInfo( 'replica' ) ) {
+ return true; // server is not a replica DB
+ }
+
+ $pos = $pos ?: $this->getConnection( DB_MASTER )->getMasterPos();
+ if ( !( $pos instanceof DBMasterPos ) ) {
+ return false; // something is misconfigured
+ }
+
+ $result = $conn->masterPosWait( $pos, $timeout );
+ if ( $result == -1 || is_null( $result ) ) {
+ $msg = __METHOD__ . ": Timed out waiting on {$conn->getServer()} pos {$pos}";
+ $this->replLogger->warning( "$msg" );
+ $ok = false;
+ } else {
+ $this->replLogger->info( __METHOD__ . ": Done" );
+ $ok = true;
+ }
+
+ return $ok;
+ }
+
+ /**
+ * Clear the cache for slag lag delay times
+ *
+ * This is only used for testing
+ * @since 1.26
+ */
+ public function clearLagTimeCache() {
+ $this->getLoadMonitor()->clearCaches();
+ }
+
+ /**
+ * Set a callback via IDatabase::setTransactionListener() on
+ * all current and future master connections of this load balancer
+ *
+ * @param string $name Callback name
+ * @param callable|null $callback
+ * @since 1.28
+ */
+ public function setTransactionListener( $name, callable $callback = null ) {
+ if ( $callback ) {
+ $this->trxRecurringCallbacks[$name] = $callback;
+ } else {
+ unset( $this->trxRecurringCallbacks[$name] );
+ }
+ $this->forEachOpenMasterConnection(
+ function ( IDatabase $conn ) use ( $name, $callback ) {
+ $conn->setTransactionListener( $name, $callback );
+ }
+ );
+ }
+
+ /**
+ * Set a new table prefix for the existing local domain ID for testing
+ *
+ * @param string $prefix
+ * @since 1.28
+ */
+ public function setDomainPrefix( $prefix ) {
+ list( $dbName, ) = explode( '-', $this->localDomain, 2 );
+
+ $this->localDomain = "{$dbName}-{$prefix}";
+ }
+}
dépôts / lhc / web / wiklou.git / commitdiff