4ccb228bde
Also added LBFactory::setTableAlias() for consistency with this Change-Id: Ie49003ff8fd5b99f75db9fae8fe0a184444254d4
1837 lines
59 KiB
PHP
1837 lines
59 KiB
PHP
<?php
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/**
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* Database load balancing manager
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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namespace Wikimedia\Rdbms;
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use Psr\Log\LoggerInterface;
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use Psr\Log\NullLogger;
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use Wikimedia\ScopedCallback;
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use BagOStuff;
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use EmptyBagOStuff;
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use WANObjectCache;
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use ArrayUtils;
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use InvalidArgumentException;
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use RuntimeException;
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use Exception;
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/**
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* Database connection, tracking, load balancing, and transaction manager for a cluster
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*
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* @ingroup Database
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*/
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class LoadBalancer implements ILoadBalancer {
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/** @var array[] Map of (server index => server config array) */
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private $servers;
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/** @var Database[][][] Map of (connection category => server index => IDatabase[]) */
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private $conns;
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/** @var float[] Map of (server index => weight) */
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private $loads;
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/** @var array[] Map of (group => server index => weight) */
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private $groupLoads;
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/** @var bool Whether to disregard replica DB lag as a factor in replica DB selection */
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private $allowLagged;
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/** @var int Seconds to spend waiting on replica DB lag to resolve */
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private $waitTimeout;
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/** @var array The LoadMonitor configuration */
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private $loadMonitorConfig;
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/** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
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private $tableAliases = [];
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/** @var string[] Map of (index alias => index) */
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private $indexAliases = [];
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/** @var ILoadMonitor */
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private $loadMonitor;
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/** @var ChronologyProtector|null */
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private $chronProt;
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/** @var BagOStuff */
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private $srvCache;
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/** @var WANObjectCache */
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private $wanCache;
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/** @var object|string Class name or object With profileIn/profileOut methods */
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protected $profiler;
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/** @var TransactionProfiler */
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protected $trxProfiler;
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/** @var LoggerInterface */
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protected $replLogger;
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/** @var LoggerInterface */
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protected $connLogger;
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/** @var LoggerInterface */
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protected $queryLogger;
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/** @var LoggerInterface */
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protected $perfLogger;
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/** @var Database DB connection object that caused a problem */
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private $errorConnection;
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/** @var int The generic (not query grouped) replica DB index (of $mServers) */
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private $readIndex;
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/** @var bool|DBMasterPos False if not set */
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private $waitForPos;
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/** @var bool Whether the generic reader fell back to a lagged replica DB */
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private $laggedReplicaMode = false;
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/** @var bool Whether the generic reader fell back to a lagged replica DB */
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private $allReplicasDownMode = false;
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/** @var string The last DB selection or connection error */
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private $lastError = 'Unknown error';
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/** @var string|bool Reason the LB is read-only or false if not */
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private $readOnlyReason = false;
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/** @var int Total connections opened */
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private $connsOpened = 0;
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/** @var string|bool String if a requested DBO_TRX transaction round is active */
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private $trxRoundId = false;
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/** @var array[] Map of (name => callable) */
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private $trxRecurringCallbacks = [];
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/** @var DatabaseDomain Local Domain ID and default for selectDB() calls */
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private $localDomain;
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/** @var string Alternate ID string for the domain instead of DatabaseDomain::getId() */
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private $localDomainIdAlias;
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/** @var string Current server name */
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private $host;
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/** @var bool Whether this PHP instance is for a CLI script */
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protected $cliMode;
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/** @var string Agent name for query profiling */
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protected $agent;
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/** @var callable Exception logger */
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private $errorLogger;
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/** @var bool */
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private $disabled = false;
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/** @var bool */
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private $chronProtInitialized = false;
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/** @var int */
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private $maxLag = self::MAX_LAG_DEFAULT;
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/** @var int Warn when this many connection are held */
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const CONN_HELD_WARN_THRESHOLD = 10;
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/** @var int Default 'maxLag' when unspecified */
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const MAX_LAG_DEFAULT = 10;
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/** @var int Default 'waitTimeout' when unspecified */
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const MAX_WAIT_DEFAULT = 10;
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/** @var int Seconds to cache master server read-only status */
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const TTL_CACHE_READONLY = 5;
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const KEY_LOCAL = 'local';
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const KEY_FOREIGN_FREE = 'foreignFree';
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const KEY_FOREIGN_INUSE = 'foreignInUse';
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const KEY_LOCAL_NOROUND = 'localAutoCommit';
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const KEY_FOREIGN_FREE_NOROUND = 'foreignFreeAutoCommit';
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const KEY_FOREIGN_INUSE_NOROUND = 'foreignInUseAutoCommit';
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public function __construct( array $params ) {
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if ( !isset( $params['servers'] ) ) {
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throw new InvalidArgumentException( __CLASS__ . ': missing servers parameter' );
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}
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$this->servers = $params['servers'];
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foreach ( $this->servers as $i => $server ) {
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if ( $i == 0 ) {
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$this->servers[$i]['master'] = true;
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} else {
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$this->servers[$i]['replica'] = true;
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}
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}
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$localDomain = isset( $params['localDomain'] )
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? DatabaseDomain::newFromId( $params['localDomain'] )
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: DatabaseDomain::newUnspecified();
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$this->setLocalDomain( $localDomain );
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$this->waitTimeout = isset( $params['waitTimeout'] )
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? $params['waitTimeout']
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: self::MAX_WAIT_DEFAULT;
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$this->readIndex = -1;
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$this->conns = [
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// Connection were transaction rounds may be applied
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self::KEY_LOCAL => [],
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self::KEY_FOREIGN_INUSE => [],
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self::KEY_FOREIGN_FREE => [],
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// Auto-committing counterpart connections that ignore transaction rounds
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self::KEY_LOCAL_NOROUND => [],
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self::KEY_FOREIGN_INUSE_NOROUND => [],
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self::KEY_FOREIGN_FREE_NOROUND => []
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];
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$this->loads = [];
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$this->waitForPos = false;
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$this->allowLagged = false;
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if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) {
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$this->readOnlyReason = $params['readOnlyReason'];
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}
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if ( isset( $params['maxLag'] ) ) {
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$this->maxLag = $params['maxLag'];
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}
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if ( isset( $params['loadMonitor'] ) ) {
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$this->loadMonitorConfig = $params['loadMonitor'];
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} else {
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$this->loadMonitorConfig = [ 'class' => 'LoadMonitorNull' ];
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}
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$this->loadMonitorConfig += [ 'lagWarnThreshold' => $this->maxLag ];
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foreach ( $params['servers'] as $i => $server ) {
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$this->loads[$i] = $server['load'];
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if ( isset( $server['groupLoads'] ) ) {
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foreach ( $server['groupLoads'] as $group => $ratio ) {
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if ( !isset( $this->groupLoads[$group] ) ) {
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$this->groupLoads[$group] = [];
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}
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$this->groupLoads[$group][$i] = $ratio;
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}
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}
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}
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if ( isset( $params['srvCache'] ) ) {
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$this->srvCache = $params['srvCache'];
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} else {
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$this->srvCache = new EmptyBagOStuff();
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}
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if ( isset( $params['wanCache'] ) ) {
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$this->wanCache = $params['wanCache'];
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} else {
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$this->wanCache = WANObjectCache::newEmpty();
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}
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$this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
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if ( isset( $params['trxProfiler'] ) ) {
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$this->trxProfiler = $params['trxProfiler'];
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} else {
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$this->trxProfiler = new TransactionProfiler();
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}
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$this->errorLogger = isset( $params['errorLogger'] )
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? $params['errorLogger']
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: function ( Exception $e ) {
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trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
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};
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foreach ( [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ] as $key ) {
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$this->$key = isset( $params[$key] ) ? $params[$key] : new NullLogger();
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}
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$this->host = isset( $params['hostname'] )
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? $params['hostname']
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: ( gethostname() ?: 'unknown' );
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$this->cliMode = isset( $params['cliMode'] )
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? $params['cliMode']
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: ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
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$this->agent = isset( $params['agent'] ) ? $params['agent'] : '';
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if ( isset( $params['chronologyProtector'] ) ) {
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$this->chronProt = $params['chronologyProtector'];
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}
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}
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/**
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* Get the local (and default) database domain ID of connection handles
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*
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* @see DatabaseDomain
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* @return string Database domain ID; this specifies DB name, schema, and table prefix
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* @since 1.31
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*/
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public function getLocalDomainID() {
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return $this->localDomain->getId();
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}
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/**
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* Get a LoadMonitor instance
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*
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* @return ILoadMonitor
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*/
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private function getLoadMonitor() {
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if ( !isset( $this->loadMonitor ) ) {
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$compat = [
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'LoadMonitor' => LoadMonitor::class,
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'LoadMonitorNull' => LoadMonitorNull::class,
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'LoadMonitorMySQL' => LoadMonitorMySQL::class,
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];
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$class = $this->loadMonitorConfig['class'];
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if ( isset( $compat[$class] ) ) {
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$class = $compat[$class];
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}
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$this->loadMonitor = new $class(
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$this, $this->srvCache, $this->wanCache, $this->loadMonitorConfig );
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$this->loadMonitor->setLogger( $this->replLogger );
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}
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return $this->loadMonitor;
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}
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/**
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* @param array $loads
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* @param bool|string $domain Domain to get non-lagged for
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* @param int $maxLag Restrict the maximum allowed lag to this many seconds
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* @return bool|int|string
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*/
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private function getRandomNonLagged( array $loads, $domain = false, $maxLag = INF ) {
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$lags = $this->getLagTimes( $domain );
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# Unset excessively lagged servers
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foreach ( $lags as $i => $lag ) {
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if ( $i != 0 ) {
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# How much lag this server nominally is allowed to have
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$maxServerLag = isset( $this->servers[$i]['max lag'] )
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? $this->servers[$i]['max lag']
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: $this->maxLag; // default
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# Constrain that futher by $maxLag argument
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$maxServerLag = min( $maxServerLag, $maxLag );
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$host = $this->getServerName( $i );
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if ( $lag === false && !is_infinite( $maxServerLag ) ) {
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$this->replLogger->error(
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__METHOD__ .
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": server {host} is not replicating?", [ 'host' => $host ] );
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unset( $loads[$i] );
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} elseif ( $lag > $maxServerLag ) {
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$this->replLogger->info(
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__METHOD__ .
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": server {host} has {lag} seconds of lag (>= {maxlag})",
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[ 'host' => $host, 'lag' => $lag, 'maxlag' => $maxServerLag ]
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);
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unset( $loads[$i] );
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}
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}
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}
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# Find out if all the replica DBs with non-zero load are lagged
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$sum = 0;
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foreach ( $loads as $load ) {
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$sum += $load;
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}
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if ( $sum == 0 ) {
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# No appropriate DB servers except maybe the master and some replica DBs with zero load
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# Do NOT use the master
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# Instead, this function will return false, triggering read-only mode,
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# and a lagged replica DB will be used instead.
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return false;
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}
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if ( count( $loads ) == 0 ) {
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return false;
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}
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# Return a random representative of the remainder
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return ArrayUtils::pickRandom( $loads );
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}
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public function getReaderIndex( $group = false, $domain = false ) {
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if ( count( $this->servers ) == 1 ) {
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// Skip the load balancing if there's only one server
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return $this->getWriterIndex();
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} elseif ( $group === false && $this->readIndex >= 0 ) {
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// Shortcut if the generic reader index was already cached
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return $this->readIndex;
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}
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if ( $group !== false ) {
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// Use the server weight array for this load group
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if ( isset( $this->groupLoads[$group] ) ) {
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$loads = $this->groupLoads[$group];
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} else {
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// No loads for this group, return false and the caller can use some other group
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$this->connLogger->info( __METHOD__ . ": no loads for group $group" );
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return false;
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}
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} else {
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// Use the generic load group
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$loads = $this->loads;
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}
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// Scale the configured load ratios according to each server's load and state
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$this->getLoadMonitor()->scaleLoads( $loads, $domain );
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// Pick a server to use, accounting for weights, load, lag, and mWaitForPos
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list( $i, $laggedReplicaMode ) = $this->pickReaderIndex( $loads, $domain );
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if ( $i === false ) {
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// Replica DB connection unsuccessful
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return false;
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}
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if ( $this->waitForPos && $i != $this->getWriterIndex() ) {
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// Before any data queries are run, wait for the server to catch up to the
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// specified position. This is used to improve session consistency. Note that
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// when LoadBalancer::waitFor() sets mWaitForPos, the waiting triggers here,
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// so update laggedReplicaMode as needed for consistency.
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if ( !$this->doWait( $i ) ) {
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$laggedReplicaMode = true;
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}
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}
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if ( $this->readIndex <= 0 && $this->loads[$i] > 0 && $group === false ) {
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// Cache the generic reader index for future ungrouped DB_REPLICA handles
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$this->readIndex = $i;
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// Record if the generic reader index is in "lagged replica DB" mode
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if ( $laggedReplicaMode ) {
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$this->laggedReplicaMode = true;
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}
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}
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$serverName = $this->getServerName( $i );
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$this->connLogger->debug( __METHOD__ . ": using server $serverName for group '$group'" );
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return $i;
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}
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/**
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* @param array $loads List of server weights
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* @param string|bool $domain
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* @return array (reader index, lagged replica mode) or false on failure
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*/
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private function pickReaderIndex( array $loads, $domain = false ) {
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if ( !count( $loads ) ) {
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throw new InvalidArgumentException( "Empty server array given to LoadBalancer" );
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}
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/** @var int|bool $i Index of selected server */
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$i = false;
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/** @var bool $laggedReplicaMode Whether server is considered lagged */
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$laggedReplicaMode = false;
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// Quickly look through the available servers for a server that meets criteria...
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$currentLoads = $loads;
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while ( count( $currentLoads ) ) {
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if ( $this->allowLagged || $laggedReplicaMode ) {
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$i = ArrayUtils::pickRandom( $currentLoads );
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} else {
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$i = false;
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if ( $this->waitForPos && $this->waitForPos->asOfTime() ) {
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// ChronologyProtecter sets mWaitForPos for session consistency.
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// This triggers doWait() after connect, so it's especially good to
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// avoid lagged servers so as to avoid excessive delay in that method.
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$ago = microtime( true ) - $this->waitForPos->asOfTime();
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// Aim for <= 1 second of waiting (being too picky can backfire)
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$i = $this->getRandomNonLagged( $currentLoads, $domain, $ago + 1 );
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}
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if ( $i === false ) {
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// Any server with less lag than it's 'max lag' param is preferable
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$i = $this->getRandomNonLagged( $currentLoads, $domain );
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}
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if ( $i === false && count( $currentLoads ) != 0 ) {
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// All replica DBs lagged. Switch to read-only mode
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$this->replLogger->error(
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__METHOD__ . ": all replica DBs lagged. Switch to read-only mode" );
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$i = ArrayUtils::pickRandom( $currentLoads );
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$laggedReplicaMode = true;
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}
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}
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if ( $i === false ) {
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// pickRandom() returned false.
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// This is permanent and means the configuration or the load monitor
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// wants us to return false.
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$this->connLogger->debug( __METHOD__ . ": pickRandom() returned false" );
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return [ false, false ];
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}
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$serverName = $this->getServerName( $i );
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$this->connLogger->debug( __METHOD__ . ": Using reader #$i: $serverName..." );
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$conn = $this->openConnection( $i, $domain );
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if ( !$conn ) {
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$this->connLogger->warning( __METHOD__ . ": Failed connecting to $i/$domain" );
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unset( $currentLoads[$i] ); // avoid this server next iteration
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$i = false;
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continue;
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}
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// Decrement reference counter, we are finished with this connection.
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// It will be incremented for the caller later.
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if ( $domain !== false ) {
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$this->reuseConnection( $conn );
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}
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// Return this server
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break;
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}
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// If all servers were down, quit now
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if ( !count( $currentLoads ) ) {
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$this->connLogger->error( __METHOD__ . ": all servers down" );
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}
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return [ $i, $laggedReplicaMode ];
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}
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public function waitFor( $pos ) {
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$oldPos = $this->waitForPos;
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try {
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$this->waitForPos = $pos;
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// If a generic reader connection was already established, then wait now
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$i = $this->readIndex;
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if ( $i > 0 ) {
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if ( !$this->doWait( $i ) ) {
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$this->laggedReplicaMode = true;
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}
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}
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} finally {
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// Restore the older position if it was higher since this is used for lag-protection
|
|
$this->setWaitForPositionIfHigher( $oldPos );
|
|
}
|
|
}
|
|
|
|
public function waitForOne( $pos, $timeout = null ) {
|
|
$oldPos = $this->waitForPos;
|
|
try {
|
|
$this->waitForPos = $pos;
|
|
|
|
$i = $this->readIndex;
|
|
if ( $i <= 0 ) {
|
|
// Pick a generic replica DB if there isn't one yet
|
|
$readLoads = $this->loads;
|
|
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
|
|
}
|
|
} finally {
|
|
# Restore the old position, as this is not used for lag-protection but for throttling
|
|
$this->waitForPos = $oldPos;
|
|
}
|
|
|
|
return $ok;
|
|
}
|
|
|
|
public function waitForAll( $pos, $timeout = null ) {
|
|
$timeout = $timeout ?: $this->waitTimeout;
|
|
|
|
$oldPos = $this->waitForPos;
|
|
try {
|
|
$this->waitForPos = $pos;
|
|
$serverCount = count( $this->servers );
|
|
|
|
$ok = true;
|
|
for ( $i = 1; $i < $serverCount; $i++ ) {
|
|
if ( $this->loads[$i] > 0 ) {
|
|
$start = microtime( true );
|
|
$ok = $this->doWait( $i, true, $timeout ) && $ok;
|
|
$timeout -= ( microtime( true ) - $start );
|
|
if ( $timeout <= 0 ) {
|
|
break; // timeout reached
|
|
}
|
|
}
|
|
}
|
|
} finally {
|
|
# Restore the old position, as this is not used for lag-protection but for throttling
|
|
$this->waitForPos = $oldPos;
|
|
}
|
|
|
|
return $ok;
|
|
}
|
|
|
|
/**
|
|
* @param DBMasterPos|bool $pos
|
|
*/
|
|
private function setWaitForPositionIfHigher( $pos ) {
|
|
if ( !$pos ) {
|
|
return;
|
|
}
|
|
|
|
if ( !$this->waitForPos || $pos->hasReached( $this->waitForPos ) ) {
|
|
$this->waitForPos = $pos;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @param int $i
|
|
* @return IDatabase|bool
|
|
*/
|
|
public function getAnyOpenConnection( $i ) {
|
|
foreach ( $this->conns as $connsByServer ) {
|
|
if ( !empty( $connsByServer[$i] ) ) {
|
|
/** @var IDatabase[] $serverConns */
|
|
$serverConns = $connsByServer[$i];
|
|
|
|
return reset( $serverConns );
|
|
}
|
|
}
|
|
|
|
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 "waitTimeout" given to __construct()
|
|
* @return bool
|
|
*/
|
|
protected function doWait( $index, $open = false, $timeout = null ) {
|
|
$timeout = max( 1, $timeout ?: $this->waitTimeout );
|
|
|
|
// 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, 'v1' );
|
|
/** @var DBMasterPos $knownReachedPos */
|
|
$knownReachedPos = $this->srvCache->get( $key );
|
|
if (
|
|
$knownReachedPos instanceof DBMasterPos &&
|
|
$knownReachedPos->hasReached( $this->waitForPos )
|
|
) {
|
|
$this->replLogger->debug(
|
|
__METHOD__ .
|
|
': replica DB {dbserver} known to be caught up (pos >= $knownReachedPos).',
|
|
[ 'dbserver' => $server ]
|
|
);
|
|
return true;
|
|
}
|
|
|
|
// Find a connection to wait on, creating one if needed and allowed
|
|
$close = false; // close the connection afterwards
|
|
$conn = $this->getAnyOpenConnection( $index );
|
|
if ( !$conn ) {
|
|
if ( !$open ) {
|
|
$this->replLogger->debug(
|
|
__METHOD__ . ': no connection open for {dbserver}',
|
|
[ 'dbserver' => $server ]
|
|
);
|
|
|
|
return false;
|
|
} else {
|
|
$conn = $this->openConnection( $index, self::DOMAIN_ANY );
|
|
if ( !$conn ) {
|
|
$this->replLogger->warning(
|
|
__METHOD__ . ': failed to connect to {dbserver}',
|
|
[ 'dbserver' => $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 {dbserver} to catch up...',
|
|
[ 'dbserver' => $server ]
|
|
);
|
|
|
|
$result = $conn->masterPosWait( $this->waitForPos, $timeout );
|
|
|
|
if ( $result === null ) {
|
|
$this->replLogger->warning(
|
|
__METHOD__ . ': Errored out waiting on {host} pos {pos}',
|
|
[
|
|
'host' => $server,
|
|
'pos' => $this->waitForPos,
|
|
'trace' => ( new RuntimeException() )->getTraceAsString()
|
|
]
|
|
);
|
|
$ok = false;
|
|
} elseif ( $result == -1 ) {
|
|
$this->replLogger->warning(
|
|
__METHOD__ . ': Timed out waiting on {host} pos {pos}',
|
|
[
|
|
'host' => $server,
|
|
'pos' => $this->waitForPos,
|
|
'trace' => ( new RuntimeException() )->getTraceAsString()
|
|
]
|
|
);
|
|
$ok = false;
|
|
} else {
|
|
$this->replLogger->debug( __METHOD__ . ": done waiting" );
|
|
$ok = true;
|
|
// Remember that the DB reached this point
|
|
$this->srvCache->set( $key, $this->waitForPos, BagOStuff::TTL_DAY );
|
|
}
|
|
|
|
if ( $close ) {
|
|
$this->closeConnection( $conn );
|
|
}
|
|
|
|
return $ok;
|
|
}
|
|
|
|
public function getConnection( $i, $groups = [], $domain = false, $flags = 0 ) {
|
|
if ( $i === null || $i === false ) {
|
|
throw new InvalidArgumentException( 'Attempt to call ' . __METHOD__ .
|
|
' with invalid server index' );
|
|
}
|
|
|
|
if ( $this->localDomain->equals( $domain ) || $domain === $this->localDomainIdAlias ) {
|
|
$domain = false; // local connection requested
|
|
}
|
|
|
|
if ( ( $flags & self::CONN_TRX_AUTO ) === self::CONN_TRX_AUTO ) {
|
|
// Assuming all servers are of the same type (or similar), which is overwhelmingly
|
|
// the case, use the master server information to get the attributes. The information
|
|
// for $i cannot be used since it might be DB_REPLICA, which might require connection
|
|
// attempts in order to be resolved into a real server index.
|
|
$attributes = $this->getServerAttributes( $this->getWriterIndex() );
|
|
if ( $attributes[Database::ATTR_DB_LEVEL_LOCKING] ) {
|
|
// Callers sometimes want to (a) escape REPEATABLE-READ stateness without locking
|
|
// rows (e.g. FOR UPDATE) or (b) make small commits during a larger transactions
|
|
// to reduce lock contention. None of these apply for sqlite and using separate
|
|
// connections just causes self-deadlocks.
|
|
$flags &= ~self::CONN_TRX_AUTO;
|
|
$this->connLogger->info( __METHOD__ . ': ignoring CONN_TRX_AUTO to avoid deadlocks.' );
|
|
}
|
|
}
|
|
|
|
$groups = ( $groups === false || $groups === [] )
|
|
? [ false ] // check one "group": the generic pool
|
|
: (array)$groups;
|
|
|
|
$masterOnly = ( $i == self::DB_MASTER || $i == $this->getWriterIndex() );
|
|
$oldConnsOpened = $this->connsOpened; // connections open now
|
|
|
|
if ( $i == self::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 == self::DB_REPLICA ) {
|
|
$this->lastError = 'Unknown error'; // reset error string
|
|
# Try the general server pool if $groups are unavailable.
|
|
$i = ( $groups === [ false ] )
|
|
? 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->lastError = 'No working replica DB server: ' . $this->lastError;
|
|
// Throw an exception
|
|
$this->reportConnectionError();
|
|
return null; // not reached
|
|
}
|
|
}
|
|
|
|
# Now we have an explicit index into the servers array
|
|
$conn = $this->openConnection( $i, $domain, $flags );
|
|
if ( !$conn ) {
|
|
// Throw an exception
|
|
$this->reportConnectionError();
|
|
return null; // not reached
|
|
}
|
|
|
|
# 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( IDatabase $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( $lb::DB_REPLICA, [], $db );
|
|
* ...
|
|
* $lb->reuseConnection( $conn );
|
|
* }
|
|
* When a connection to the local DB is opened in this way, reuseConnection()
|
|
* should be ignored
|
|
*/
|
|
return;
|
|
} elseif ( $conn instanceof DBConnRef ) {
|
|
// DBConnRef already handles calling reuseConnection() and only passes the live
|
|
// Database instance to this method. Any caller passing in a DBConnRef is broken.
|
|
$this->connLogger->error(
|
|
__METHOD__ . ": got DBConnRef instance.\n" .
|
|
( new RuntimeException() )->getTraceAsString() );
|
|
|
|
return;
|
|
}
|
|
|
|
if ( $this->disabled ) {
|
|
return; // DBConnRef handle probably survived longer than the LoadBalancer
|
|
}
|
|
|
|
if ( $conn->getLBInfo( 'autoCommitOnly' ) ) {
|
|
$connFreeKey = self::KEY_FOREIGN_FREE_NOROUND;
|
|
$connInUseKey = self::KEY_FOREIGN_INUSE_NOROUND;
|
|
} else {
|
|
$connFreeKey = self::KEY_FOREIGN_FREE;
|
|
$connInUseKey = self::KEY_FOREIGN_INUSE;
|
|
}
|
|
|
|
$domain = $conn->getDomainID();
|
|
if ( !isset( $this->conns[$connInUseKey][$serverIndex][$domain] ) ) {
|
|
throw new InvalidArgumentException( __METHOD__ .
|
|
": connection $serverIndex/$domain not found; it may have already been freed." );
|
|
} elseif ( $this->conns[$connInUseKey][$serverIndex][$domain] !== $conn ) {
|
|
throw new InvalidArgumentException( __METHOD__ .
|
|
": connection $serverIndex/$domain mismatched; it may have already been freed." );
|
|
}
|
|
|
|
$conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
|
|
if ( $refCount <= 0 ) {
|
|
$this->conns[$connFreeKey][$serverIndex][$domain] = $conn;
|
|
unset( $this->conns[$connInUseKey][$serverIndex][$domain] );
|
|
if ( !$this->conns[$connInUseKey][$serverIndex] ) {
|
|
unset( $this->conns[$connInUseKey][$serverIndex] ); // clean up
|
|
}
|
|
$this->connLogger->debug( __METHOD__ . ": freed connection $serverIndex/$domain" );
|
|
} else {
|
|
$this->connLogger->debug( __METHOD__ .
|
|
": reference count for $serverIndex/$domain reduced to $refCount" );
|
|
}
|
|
}
|
|
|
|
public function getConnectionRef( $db, $groups = [], $domain = false, $flags = 0 ) {
|
|
$domain = ( $domain !== false ) ? $domain : $this->localDomain;
|
|
|
|
return new DBConnRef( $this, $this->getConnection( $db, $groups, $domain, $flags ) );
|
|
}
|
|
|
|
public function getLazyConnectionRef( $db, $groups = [], $domain = false, $flags = 0 ) {
|
|
$domain = ( $domain !== false ) ? $domain : $this->localDomain;
|
|
|
|
return new DBConnRef( $this, [ $db, $groups, $domain, $flags ] );
|
|
}
|
|
|
|
public function getMaintenanceConnectionRef( $db, $groups = [], $domain = false, $flags = 0 ) {
|
|
$domain = ( $domain !== false ) ? $domain : $this->localDomain;
|
|
|
|
return new MaintainableDBConnRef(
|
|
$this, $this->getConnection( $db, $groups, $domain, $flags ) );
|
|
}
|
|
|
|
public function openConnection( $i, $domain = false, $flags = 0 ) {
|
|
if ( $this->localDomain->equals( $domain ) || $domain === $this->localDomainIdAlias ) {
|
|
$domain = false; // local connection requested
|
|
}
|
|
|
|
if ( !$this->chronProtInitialized && $this->chronProt ) {
|
|
$this->connLogger->debug( __METHOD__ . ': calling initLB() before first connection.' );
|
|
// Load CP positions before connecting so that doWait() triggers later if needed
|
|
$this->chronProtInitialized = true;
|
|
$this->chronProt->initLB( $this );
|
|
}
|
|
|
|
// Check if an auto-commit connection is being requested. If so, it will not reuse the
|
|
// main set of DB connections but rather its own pool since:
|
|
// a) those are usually set to implicitly use transaction rounds via DBO_TRX
|
|
// b) those must support the use of explicit transaction rounds via beginMasterChanges()
|
|
$autoCommit = ( ( $flags & self::CONN_TRX_AUTO ) == self::CONN_TRX_AUTO );
|
|
|
|
if ( $domain !== false ) {
|
|
// Connection is to a foreign domain
|
|
$conn = $this->openForeignConnection( $i, $domain, $flags );
|
|
} else {
|
|
// Connection is to the local domain
|
|
$connKey = $autoCommit ? self::KEY_LOCAL_NOROUND : self::KEY_LOCAL;
|
|
if ( isset( $this->conns[$connKey][$i][0] ) ) {
|
|
$conn = $this->conns[$connKey][$i][0];
|
|
} else {
|
|
if ( !isset( $this->servers[$i] ) || !is_array( $this->servers[$i] ) ) {
|
|
throw new InvalidArgumentException( "No server with index '$i'." );
|
|
}
|
|
// Open a new connection
|
|
$server = $this->servers[$i];
|
|
$server['serverIndex'] = $i;
|
|
$server['autoCommitOnly'] = $autoCommit;
|
|
if ( $this->localDomain->getDatabase() !== null ) {
|
|
// Use the local domain table prefix if the local domain is specified
|
|
$server['tablePrefix'] = $this->localDomain->getTablePrefix();
|
|
}
|
|
$conn = $this->reallyOpenConnection( $server, $this->localDomain );
|
|
$host = $this->getServerName( $i );
|
|
if ( $conn->isOpen() ) {
|
|
$this->connLogger->debug(
|
|
__METHOD__ . ": connected to database $i at '$host'." );
|
|
$this->conns[$connKey][$i][0] = $conn;
|
|
} else {
|
|
$this->connLogger->warning(
|
|
__METHOD__ . ": failed to connect to database $i at '$host'." );
|
|
$this->errorConnection = $conn;
|
|
$conn = false;
|
|
}
|
|
}
|
|
}
|
|
|
|
if ( $conn instanceof IDatabase && !$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->errorConnection = $conn;
|
|
$conn = false;
|
|
}
|
|
|
|
if ( $autoCommit && $conn instanceof IDatabase ) {
|
|
$conn->clearFlag( $conn::DBO_TRX ); // auto-commit mode
|
|
}
|
|
|
|
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->errorConnection.
|
|
*
|
|
* @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
|
|
* @param int $flags Class CONN_* constant bitfield
|
|
* @return Database
|
|
*/
|
|
private function openForeignConnection( $i, $domain, $flags = 0 ) {
|
|
$domainInstance = DatabaseDomain::newFromId( $domain );
|
|
$dbName = $domainInstance->getDatabase();
|
|
$prefix = $domainInstance->getTablePrefix();
|
|
$autoCommit = ( ( $flags & self::CONN_TRX_AUTO ) == self::CONN_TRX_AUTO );
|
|
|
|
if ( $autoCommit ) {
|
|
$connFreeKey = self::KEY_FOREIGN_FREE_NOROUND;
|
|
$connInUseKey = self::KEY_FOREIGN_INUSE_NOROUND;
|
|
} else {
|
|
$connFreeKey = self::KEY_FOREIGN_FREE;
|
|
$connInUseKey = self::KEY_FOREIGN_INUSE;
|
|
}
|
|
|
|
if ( isset( $this->conns[$connInUseKey][$i][$domain] ) ) {
|
|
// Reuse an in-use connection for the same domain
|
|
$conn = $this->conns[$connInUseKey][$i][$domain];
|
|
$this->connLogger->debug( __METHOD__ . ": reusing connection $i/$domain" );
|
|
} elseif ( isset( $this->conns[$connFreeKey][$i][$domain] ) ) {
|
|
// Reuse a free connection for the same domain
|
|
$conn = $this->conns[$connFreeKey][$i][$domain];
|
|
unset( $this->conns[$connFreeKey][$i][$domain] );
|
|
$this->conns[$connInUseKey][$i][$domain] = $conn;
|
|
$this->connLogger->debug( __METHOD__ . ": reusing free connection $i/$domain" );
|
|
} elseif ( !empty( $this->conns[$connFreeKey][$i] ) ) {
|
|
// Reuse a free connection from another domain
|
|
$conn = reset( $this->conns[$connFreeKey][$i] );
|
|
$oldDomain = key( $this->conns[$connFreeKey][$i] );
|
|
if ( strlen( $dbName ) && !$conn->selectDB( $dbName ) ) {
|
|
$this->lastError = "Error selecting database '$dbName' on server " .
|
|
$conn->getServer() . " from client host {$this->host}";
|
|
$this->errorConnection = $conn;
|
|
$conn = false;
|
|
} else {
|
|
$conn->tablePrefix( $prefix );
|
|
unset( $this->conns[$connFreeKey][$i][$oldDomain] );
|
|
// Note that if $domain is an empty string, getDomainID() might not match it
|
|
$this->conns[$connInUseKey][$i][$conn->getDomainId()] = $conn;
|
|
$this->connLogger->debug( __METHOD__ .
|
|
": reusing free connection from $oldDomain for $domain" );
|
|
}
|
|
} else {
|
|
if ( !isset( $this->servers[$i] ) || !is_array( $this->servers[$i] ) ) {
|
|
throw new InvalidArgumentException( "No server with index '$i'." );
|
|
}
|
|
// Open a new connection
|
|
$server = $this->servers[$i];
|
|
$server['serverIndex'] = $i;
|
|
$server['foreignPoolRefCount'] = 0;
|
|
$server['foreign'] = true;
|
|
$server['autoCommitOnly'] = $autoCommit;
|
|
$conn = $this->reallyOpenConnection( $server, $domainInstance );
|
|
if ( !$conn->isOpen() ) {
|
|
$this->connLogger->warning( __METHOD__ . ": connection error for $i/$domain" );
|
|
$this->errorConnection = $conn;
|
|
$conn = false;
|
|
} else {
|
|
$conn->tablePrefix( $prefix ); // as specified
|
|
// Note that if $domain is an empty string, getDomainID() might not match it
|
|
$this->conns[$connInUseKey][$i][$conn->getDomainID()] = $conn;
|
|
$this->connLogger->debug( __METHOD__ . ": opened new connection for $i/$domain" );
|
|
}
|
|
}
|
|
|
|
// Increment reference count
|
|
if ( $conn instanceof IDatabase ) {
|
|
$refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
|
|
$conn->setLBInfo( 'foreignPoolRefCount', $refCount + 1 );
|
|
}
|
|
|
|
return $conn;
|
|
}
|
|
|
|
public function getServerAttributes( $i ) {
|
|
return Database::attributesFromType(
|
|
$this->getServerType( $i ),
|
|
isset( $this->servers[$i]['driver'] ) ? $this->servers[$i]['driver'] : null
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Test if the specified index represents an open connection
|
|
*
|
|
* @param int $index Server index
|
|
* @access private
|
|
* @return bool
|
|
*/
|
|
private function isOpen( $index ) {
|
|
if ( !is_int( $index ) ) {
|
|
return false;
|
|
}
|
|
|
|
return (bool)$this->getAnyOpenConnection( $index );
|
|
}
|
|
|
|
/**
|
|
* Open a new network connection to a server (uncached)
|
|
*
|
|
* Returns a Database object whether or not the connection was successful.
|
|
*
|
|
* @param array $server
|
|
* @param DatabaseDomain $domainOverride Use an unspecified domain to not select any database
|
|
* @return Database
|
|
* @throws DBAccessError
|
|
* @throws InvalidArgumentException
|
|
*/
|
|
protected function reallyOpenConnection( array $server, DatabaseDomain $domainOverride ) {
|
|
if ( $this->disabled ) {
|
|
throw new DBAccessError();
|
|
}
|
|
|
|
// Handle $domainOverride being a specified or an unspecified domain
|
|
if ( $domainOverride->getDatabase() === null ) {
|
|
// Normally, an RDBMS requires a DB name specified on connection and the $server
|
|
// configuration array is assumed to already specify an appropriate DB name.
|
|
if ( $server['type'] === 'mysql' ) {
|
|
// For MySQL, DATABASE and SCHEMA are synonyms, connections need not specify a DB,
|
|
// and the DB name in $server might not exist due to legacy reasons (the default
|
|
// domain used to ignore the local LB domain, even when mismatched).
|
|
$server['dbname'] = null;
|
|
}
|
|
} else {
|
|
$server['dbname'] = $domainOverride->getDatabase();
|
|
$server['schema'] = $domainOverride->getSchema();
|
|
}
|
|
|
|
// 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)" );
|
|
}
|
|
|
|
$server['srvCache'] = $this->srvCache;
|
|
// Set loggers and profilers
|
|
$server['connLogger'] = $this->connLogger;
|
|
$server['queryLogger'] = $this->queryLogger;
|
|
$server['errorLogger'] = $this->errorLogger;
|
|
$server['profiler'] = $this->profiler;
|
|
$server['trxProfiler'] = $this->trxProfiler;
|
|
// Use the same agent and PHP mode for all DB handles
|
|
$server['cliMode'] = $this->cliMode;
|
|
$server['agent'] = $this->agent;
|
|
// Use DBO_DEFAULT flags by default for LoadBalancer managed databases. Assume that the
|
|
// application calls LoadBalancer::commitMasterChanges() before the PHP script completes.
|
|
$server['flags'] = isset( $server['flags'] ) ? $server['flags'] : IDatabase::DBO_DEFAULT;
|
|
|
|
// Create a live connection object
|
|
try {
|
|
$db = Database::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( self::DB_MASTER, [], $db->getDomainID() )
|
|
);
|
|
$db->setTableAliases( $this->tableAliases );
|
|
$db->setIndexAliases( $this->indexAliases );
|
|
|
|
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
|
|
*/
|
|
private function reportConnectionError() {
|
|
$conn = $this->errorConnection; // the connection which caused the error
|
|
$context = [
|
|
'method' => __METHOD__,
|
|
'last_error' => $this->lastError,
|
|
];
|
|
|
|
if ( $conn instanceof IDatabase ) {
|
|
$context['db_server'] = $conn->getServer();
|
|
$this->connLogger->warning(
|
|
__METHOD__ . ": connection error: {last_error} ({db_server})",
|
|
$context
|
|
);
|
|
|
|
// throws DBConnectionError
|
|
$conn->reportConnectionError( "{$this->lastError} ({$context['db_server']})" );
|
|
} else {
|
|
// No last connection, probably due to all servers being too busy
|
|
$this->connLogger->error(
|
|
__METHOD__ .
|
|
": 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->lastError );
|
|
}
|
|
}
|
|
|
|
public function getWriterIndex() {
|
|
return 0;
|
|
}
|
|
|
|
public function haveIndex( $i ) {
|
|
return array_key_exists( $i, $this->servers );
|
|
}
|
|
|
|
public function isNonZeroLoad( $i ) {
|
|
return array_key_exists( $i, $this->servers ) && $this->loads[$i] != 0;
|
|
}
|
|
|
|
public function getServerCount() {
|
|
return count( $this->servers );
|
|
}
|
|
|
|
public function getServerName( $i ) {
|
|
if ( isset( $this->servers[$i]['hostName'] ) ) {
|
|
$name = $this->servers[$i]['hostName'];
|
|
} elseif ( isset( $this->servers[$i]['host'] ) ) {
|
|
$name = $this->servers[$i]['host'];
|
|
} else {
|
|
$name = '';
|
|
}
|
|
|
|
return ( $name != '' ) ? $name : 'localhost';
|
|
}
|
|
|
|
public function getServerType( $i ) {
|
|
return isset( $this->servers[$i]['type'] ) ? $this->servers[$i]['type'] : 'unknown';
|
|
}
|
|
|
|
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->servers );
|
|
for ( $i = 1; $i < $serverCount; $i++ ) {
|
|
$conn = $this->getAnyOpenConnection( $i );
|
|
if ( $conn ) {
|
|
return $conn->getReplicaPos();
|
|
}
|
|
}
|
|
} else {
|
|
return $masterConn->getMasterPos();
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
public function disable() {
|
|
$this->closeAll();
|
|
$this->disabled = true;
|
|
}
|
|
|
|
public function closeAll() {
|
|
$this->forEachOpenConnection( function ( IDatabase $conn ) {
|
|
$host = $conn->getServer();
|
|
$this->connLogger->debug(
|
|
__METHOD__ . ": closing connection to database '$host'." );
|
|
$conn->close();
|
|
} );
|
|
|
|
$this->conns = [
|
|
self::KEY_LOCAL => [],
|
|
self::KEY_FOREIGN_INUSE => [],
|
|
self::KEY_FOREIGN_FREE => [],
|
|
self::KEY_LOCAL_NOROUND => [],
|
|
self::KEY_FOREIGN_INUSE_NOROUND => [],
|
|
self::KEY_FOREIGN_FREE_NOROUND => []
|
|
];
|
|
$this->connsOpened = 0;
|
|
}
|
|
|
|
public function closeConnection( IDatabase $conn ) {
|
|
$serverIndex = $conn->getLBInfo( 'serverIndex' ); // second index level of mConns
|
|
foreach ( $this->conns as $type => $connsByServer ) {
|
|
if ( !isset( $connsByServer[$serverIndex] ) ) {
|
|
continue;
|
|
}
|
|
|
|
foreach ( $connsByServer[$serverIndex] as $i => $trackedConn ) {
|
|
if ( $conn === $trackedConn ) {
|
|
$host = $this->getServerName( $i );
|
|
$this->connLogger->debug(
|
|
__METHOD__ . ": closing connection to database $i at '$host'." );
|
|
unset( $this->conns[$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 ) )
|
|
);
|
|
}
|
|
}
|
|
|
|
public function finalizeMasterChanges() {
|
|
$this->forEachOpenMasterConnection( function ( Database $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 );
|
|
} );
|
|
}
|
|
|
|
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 of $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."
|
|
);
|
|
}
|
|
} );
|
|
}
|
|
|
|
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 ( Database $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 = [];
|
|
|
|
/** @noinspection PhpUnusedLocalVariableInspection */
|
|
$scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
|
|
|
|
$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 ) )
|
|
);
|
|
}
|
|
}
|
|
|
|
public function runMasterPostTrxCallbacks( $type ) {
|
|
$e = null; // first exception
|
|
$this->forEachOpenMasterConnection( function ( Database $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->info( __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;
|
|
}
|
|
|
|
public function rollbackMasterChanges( $fname = __METHOD__ ) {
|
|
$restore = ( $this->trxRoundId !== false );
|
|
$this->trxRoundId = false;
|
|
$this->forEachOpenMasterConnection(
|
|
function ( IDatabase $conn ) use ( $fname, $restore ) {
|
|
if ( $conn->writesOrCallbacksPending() || $conn->explicitTrxActive() ) {
|
|
$conn->rollback( $fname, $conn::FLUSHING_ALL_PEERS );
|
|
}
|
|
if ( $restore ) {
|
|
$this->undoTransactionRoundFlags( $conn );
|
|
}
|
|
}
|
|
);
|
|
}
|
|
|
|
public function suppressTransactionEndCallbacks() {
|
|
$this->forEachOpenMasterConnection( function ( Database $conn ) {
|
|
$conn->setTrxEndCallbackSuppression( true );
|
|
} );
|
|
}
|
|
|
|
/**
|
|
* @param IDatabase $conn
|
|
*/
|
|
private function applyTransactionRoundFlags( IDatabase $conn ) {
|
|
if ( $conn->getLBInfo( 'autoCommitOnly' ) ) {
|
|
return; // transaction rounds do not apply to these connections
|
|
}
|
|
|
|
if ( $conn->getFlag( $conn::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( $conn::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->getLBInfo( 'autoCommitOnly' ) ) {
|
|
return; // transaction rounds do not apply to these connections
|
|
}
|
|
|
|
if ( $conn->getFlag( $conn::DBO_DEFAULT ) ) {
|
|
$conn->restoreFlags( $conn::RESTORE_PRIOR );
|
|
}
|
|
}
|
|
|
|
public function flushReplicaSnapshots( $fname = __METHOD__ ) {
|
|
$this->forEachOpenReplicaConnection( function ( IDatabase $conn ) {
|
|
$conn->flushSnapshot( __METHOD__ );
|
|
} );
|
|
}
|
|
|
|
public function hasMasterConnection() {
|
|
return $this->isOpen( $this->getWriterIndex() );
|
|
}
|
|
|
|
public function hasMasterChanges() {
|
|
$pending = 0;
|
|
$this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$pending ) {
|
|
$pending |= $conn->writesOrCallbacksPending();
|
|
} );
|
|
|
|
return (bool)$pending;
|
|
}
|
|
|
|
public function lastMasterChangeTimestamp() {
|
|
$lastTime = false;
|
|
$this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$lastTime ) {
|
|
$lastTime = max( $lastTime, $conn->lastDoneWrites() );
|
|
} );
|
|
|
|
return $lastTime;
|
|
}
|
|
|
|
public function hasOrMadeRecentMasterChanges( $age = null ) {
|
|
$age = ( $age === null ) ? $this->waitTimeout : $age;
|
|
|
|
return ( $this->hasMasterChanges()
|
|
|| $this->lastMasterChangeTimestamp() > microtime( true ) - $age );
|
|
}
|
|
|
|
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( self::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 );
|
|
}
|
|
|
|
public function laggedReplicaUsed() {
|
|
return $this->laggedReplicaMode;
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
* @since 1.27
|
|
* @deprecated Since 1.28; use laggedReplicaUsed()
|
|
*/
|
|
public function laggedSlaveUsed() {
|
|
return $this->laggedReplicaUsed();
|
|
}
|
|
|
|
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 $conn 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 ) {
|
|
$old = $this->trxProfiler->setSilenced( true );
|
|
try {
|
|
$dbw = $conn ?: $this->getConnection( self::DB_MASTER, [], $domain );
|
|
$readOnly = (int)$dbw->serverIsReadOnly();
|
|
if ( !$conn ) {
|
|
$this->reuseConnection( $dbw );
|
|
}
|
|
} catch ( DBError $e ) {
|
|
$readOnly = 0;
|
|
}
|
|
$this->trxProfiler->setSilenced( $old );
|
|
return $readOnly;
|
|
},
|
|
[ 'pcTTL' => $cache::TTL_PROC_LONG, 'busyValue' => 0 ]
|
|
);
|
|
}
|
|
|
|
public function allowLagged( $mode = null ) {
|
|
if ( $mode === null ) {
|
|
return $this->allowLagged;
|
|
}
|
|
$this->allowLagged = $mode;
|
|
|
|
return $this->allowLagged;
|
|
}
|
|
|
|
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->conns as $connsByServer ) {
|
|
foreach ( $connsByServer as $serverConns ) {
|
|
foreach ( $serverConns as $conn ) {
|
|
$mergedParams = array_merge( [ $conn ], $params );
|
|
call_user_func_array( $callback, $mergedParams );
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
public function forEachOpenMasterConnection( $callback, array $params = [] ) {
|
|
$masterIndex = $this->getWriterIndex();
|
|
foreach ( $this->conns 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 );
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
public function forEachOpenReplicaConnection( $callback, array $params = [] ) {
|
|
foreach ( $this->conns 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 ( $this->loads[$i] > 0 && $lag > $maxLag ) {
|
|
$maxLag = $lag;
|
|
$host = $this->servers[$i]['host'];
|
|
$maxIndex = $i;
|
|
}
|
|
}
|
|
|
|
return [ $host, $maxLag, $maxIndex ];
|
|
}
|
|
|
|
public function getLagTimes( $domain = false ) {
|
|
if ( $this->getServerCount() <= 1 ) {
|
|
return [ $this->getWriterIndex() => 0 ]; // no replication = no lag
|
|
}
|
|
|
|
$knownLagTimes = []; // map of (server index => 0 seconds)
|
|
$indexesWithLag = [];
|
|
foreach ( $this->servers as $i => $server ) {
|
|
if ( empty( $server['is static'] ) ) {
|
|
$indexesWithLag[] = $i; // DB server might have replication lag
|
|
} else {
|
|
$knownLagTimes[$i] = 0; // DB server is a non-replicating and read-only archive
|
|
}
|
|
}
|
|
|
|
return $this->getLoadMonitor()->getLagTimes( $indexesWithLag, $domain ) + $knownLagTimes;
|
|
}
|
|
|
|
public function safeGetLag( IDatabase $conn ) {
|
|
if ( $this->getServerCount() <= 1 ) {
|
|
return 0;
|
|
} else {
|
|
return $conn->getLag();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @param IDatabase $conn
|
|
* @param DBMasterPos|bool $pos
|
|
* @param int|null $timeout
|
|
* @return bool
|
|
*/
|
|
public function safeWaitForMasterPos( IDatabase $conn, $pos = false, $timeout = null ) {
|
|
$timeout = max( 1, $timeout ?: $this->waitTimeout );
|
|
|
|
if ( $this->getServerCount() <= 1 || !$conn->getLBInfo( 'replica' ) ) {
|
|
return true; // server is not a replica DB
|
|
}
|
|
|
|
if ( !$pos ) {
|
|
// Get the current master position, opening a connection if needed
|
|
$masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
|
|
if ( $masterConn ) {
|
|
$pos = $masterConn->getMasterPos();
|
|
} else {
|
|
$masterConn = $this->openConnection( $this->getWriterIndex(), self::DOMAIN_ANY );
|
|
$pos = $masterConn->getMasterPos();
|
|
$this->closeConnection( $masterConn );
|
|
}
|
|
}
|
|
|
|
if ( $pos instanceof DBMasterPos ) {
|
|
$result = $conn->masterPosWait( $pos, $timeout );
|
|
if ( $result == -1 || is_null( $result ) ) {
|
|
$msg = __METHOD__ . ': timed out waiting on {host} pos {pos}';
|
|
$this->replLogger->warning( $msg, [
|
|
'host' => $conn->getServer(),
|
|
'pos' => $pos,
|
|
'trace' => ( new RuntimeException() )->getTraceAsString()
|
|
] );
|
|
$ok = false;
|
|
} else {
|
|
$this->replLogger->debug( __METHOD__ . ': done waiting' );
|
|
$ok = true;
|
|
}
|
|
} else {
|
|
$ok = false; // something is misconfigured
|
|
$this->replLogger->error(
|
|
__METHOD__ . ': could not get master pos for {host}',
|
|
[
|
|
'host' => $conn->getServer(),
|
|
'trace' => ( new RuntimeException() )->getTraceAsString()
|
|
]
|
|
);
|
|
}
|
|
|
|
return $ok;
|
|
}
|
|
|
|
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 );
|
|
}
|
|
);
|
|
}
|
|
|
|
public function setTableAliases( array $aliases ) {
|
|
$this->tableAliases = $aliases;
|
|
}
|
|
|
|
public function setIndexAliases( array $aliases ) {
|
|
$this->indexAliases = $aliases;
|
|
}
|
|
|
|
public function setDomainPrefix( $prefix ) {
|
|
// Find connections to explicit foreign domains still marked as in-use...
|
|
$domainsInUse = [];
|
|
$this->forEachOpenConnection( function ( IDatabase $conn ) use ( &$domainsInUse ) {
|
|
// Once reuseConnection() is called on a handle, its reference count goes from 1 to 0.
|
|
// Until then, it is still in use by the caller (explicitly or via DBConnRef scope).
|
|
if ( $conn->getLBInfo( 'foreignPoolRefCount' ) > 0 ) {
|
|
$domainsInUse[] = $conn->getDomainID();
|
|
}
|
|
} );
|
|
|
|
// Do not switch connections to explicit foreign domains unless marked as safe
|
|
if ( $domainsInUse ) {
|
|
$domains = implode( ', ', $domainsInUse );
|
|
throw new DBUnexpectedError( null,
|
|
"Foreign domain connections are still in use ($domains)." );
|
|
}
|
|
|
|
$oldDomain = $this->localDomain->getId();
|
|
$this->setLocalDomain( new DatabaseDomain(
|
|
$this->localDomain->getDatabase(),
|
|
$this->localDomain->getSchema(),
|
|
$prefix
|
|
) );
|
|
|
|
$this->forEachOpenConnection( function ( IDatabase $db ) use ( $prefix, $oldDomain ) {
|
|
if ( !$db->getLBInfo( 'foreign' ) ) {
|
|
$db->tablePrefix( $prefix );
|
|
}
|
|
} );
|
|
}
|
|
|
|
/**
|
|
* @param DatabaseDomain $domain
|
|
*/
|
|
private function setLocalDomain( DatabaseDomain $domain ) {
|
|
$this->localDomain = $domain;
|
|
// In case a caller assumes that the domain ID is simply <db>-<prefix>, which is almost
|
|
// always true, gracefully handle the case when they fail to account for escaping.
|
|
if ( $this->localDomain->getTablePrefix() != '' ) {
|
|
$this->localDomainIdAlias =
|
|
$this->localDomain->getDatabase() . '-' . $this->localDomain->getTablePrefix();
|
|
} else {
|
|
$this->localDomainIdAlias = $this->localDomain->getDatabase();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Make PHP ignore user aborts/disconnects until the returned
|
|
* value leaves scope. This returns null and does nothing in CLI mode.
|
|
*
|
|
* @return ScopedCallback|null
|
|
*/
|
|
final protected function getScopedPHPBehaviorForCommit() {
|
|
if ( PHP_SAPI != 'cli' ) { // https://bugs.php.net/bug.php?id=47540
|
|
$old = ignore_user_abort( true ); // avoid half-finished operations
|
|
return new ScopedCallback( function () use ( $old ) {
|
|
ignore_user_abort( $old );
|
|
} );
|
|
}
|
|
|
|
return null;
|
|
}
|
|
|
|
function __destruct() {
|
|
// Avoid connection leaks for sanity
|
|
$this->disable();
|
|
}
|
|
}
|
|
|
|
class_alias( LoadBalancer::class, 'LoadBalancer' );
|