includes/libs/rdbms/lbfactory/LBFactory.php

   1 <?php
   2 /**
   3  * Generator and manager of database load balancing objects
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23
  24 namespace Wikimedia\Rdbms;
  25
  26 use Psr\Log\LoggerInterface;
  27 use Wikimedia\ScopedCallback;
  28 use BagOStuff;
  29 use EmptyBagOStuff;
  30 use WANObjectCache;
  31 use Exception;
  32 use RuntimeException;
  33 use LogicException;
  34
  35 /**
  36  * An interface for generating database load balancers
  37  * @ingroup Database
  38  */
  39 abstract class LBFactory implements ILBFactory {
  40         /** @var ChronologyProtector */
  41         protected $chronProt;
  42         /** @var object|string Class name or object With profileIn/profileOut methods */
  43         protected $profiler;
  44         /** @var TransactionProfiler */
  45         protected $trxProfiler;
  46         /** @var LoggerInterface */
  47         protected $replLogger;
  48         /** @var LoggerInterface */
  49         protected $connLogger;
  50         /** @var LoggerInterface */
  51         protected $queryLogger;
  52         /** @var LoggerInterface */
  53         protected $perfLogger;
  54         /** @var callable Error logger */
  55         protected $errorLogger;
  56         /** @var callable Deprecation logger */
  57         protected $deprecationLogger;
  58         /** @var BagOStuff */
  59         protected $srvCache;
  60         /** @var BagOStuff */
  61         protected $memStash;
  62         /** @var WANObjectCache */
  63         protected $wanCache;
  64
  65         /** @var DatabaseDomain Local domain */
  66         protected $localDomain;
  67         /** @var string Local hostname of the app server */
  68         protected $hostname;
  69         /** @var array Web request information about the client */
  70         protected $requestInfo;
  71
  72         /** @var mixed */
  73         protected $ticket;
  74         /** @var string|bool String if a requested DBO_TRX transaction round is active */
  75         protected $trxRoundId = false;
  76         /** @var string|bool Reason all LBs are read-only or false if not */
  77         protected $readOnlyReason = false;
  78         /** @var callable[] */
  79         protected $replicationWaitCallbacks = [];
  80
  81         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  82         protected $tableAliases = [];
  83         /** @var string[] Map of (index alias => index) */
  84         protected $indexAliases = [];
  85
  86         /** @var bool Whether this PHP instance is for a CLI script */
  87         protected $cliMode;
  88         /** @var string Agent name for query profiling */
  89         protected $agent;
  90
  91         private static $loggerFields =
  92                 [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];
  93
  94         public function __construct( array $conf ) {
  95                 $this->localDomain = isset( $conf['localDomain'] )
  96                         ? DatabaseDomain::newFromId( $conf['localDomain'] )
  97                         : DatabaseDomain::newUnspecified();
  98
  99                 if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
 100                         $this->readOnlyReason = $conf['readOnlyReason'];
 101                 }
 102
 103                 $this->srvCache = isset( $conf['srvCache'] ) ? $conf['srvCache'] : new EmptyBagOStuff();
 104                 $this->memStash = isset( $conf['memStash'] ) ? $conf['memStash'] : new EmptyBagOStuff();
 105                 $this->wanCache = isset( $conf['wanCache'] )
 106                         ? $conf['wanCache']
 107                         : WANObjectCache::newEmpty();
 108
 109                 foreach ( self::$loggerFields as $key ) {
 110                         $this->$key = isset( $conf[$key] ) ? $conf[$key] : new \Psr\Log\NullLogger();
 111                 }
 112                 $this->errorLogger = isset( $conf['errorLogger'] )
 113                         ? $conf['errorLogger']
 114                         : function ( Exception $e ) {
 115                                 trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 116                         };
 117                 $this->deprecationLogger = isset( $conf['deprecationLogger'] )
 118                         ? $conf['deprecationLogger']
 119                         : function ( $msg ) {
 120                                 trigger_error( $msg, E_USER_DEPRECATED );
 121                         };
 122
 123                 $this->profiler = isset( $conf['profiler'] ) ? $conf['profiler'] : null;
 124                 $this->trxProfiler = isset( $conf['trxProfiler'] )
 125                         ? $conf['trxProfiler']
 126                         : new TransactionProfiler();
 127
 128                 $this->requestInfo = [
 129                         'IPAddress' => isset( $_SERVER[ 'REMOTE_ADDR' ] ) ? $_SERVER[ 'REMOTE_ADDR' ] : '',
 130                         'UserAgent' => isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : '',
 131                         'ChronologyProtection' => 'true',
 132                         'ChronologyPositionIndex' => isset( $_GET['cpPosIndex'] ) ? $_GET['cpPosIndex'] : null
 133                 ];
 134
 135                 $this->cliMode = isset( $conf['cliMode'] )
 136                         ? $conf['cliMode']
 137                         : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 138                 $this->hostname = isset( $conf['hostname'] ) ? $conf['hostname'] : gethostname();
 139                 $this->agent = isset( $conf['agent'] ) ? $conf['agent'] : '';
 140
 141                 $this->ticket = mt_rand();
 142         }
 143
 144         public function destroy() {
 145                 $this->shutdown( self::SHUTDOWN_NO_CHRONPROT );
 146                 $this->forEachLBCallMethod( 'disable' );
 147         }
 148
 149         public function shutdown(
 150                 $mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null, &$cpIndex = null
 151         ) {
 152                 $chronProt = $this->getChronologyProtector();
 153                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 154                         $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync', $cpIndex );
 155                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 156                         $this->shutdownChronologyProtector( $chronProt, null, 'async', $cpIndex );
 157                 }
 158
 159                 $this->commitMasterChanges( __METHOD__ ); // sanity
 160         }
 161
 162         /**
 163          * @see ILBFactory::newMainLB()
 164          * @param bool $domain
 165          * @return LoadBalancer
 166          */
 167         abstract public function newMainLB( $domain = false );
 168
 169         /**
 170          * @see ILBFactory::getMainLB()
 171          * @param bool $domain
 172          * @return LoadBalancer
 173          */
 174         abstract public function getMainLB( $domain = false );
 175
 176         /**
 177          * @see ILBFactory::newExternalLB()
 178          * @param string $cluster
 179          * @return LoadBalancer
 180          */
 181         abstract public function newExternalLB( $cluster );
 182
 183         /**
 184          * @see ILBFactory::getExternalLB()
 185          * @param string $cluster
 186          * @return LoadBalancer
 187          */
 188         abstract public function getExternalLB( $cluster );
 189
 190         /**
 191          * Call a method of each tracked load balancer
 192          *
 193          * @param string $methodName
 194          * @param array $args
 195          */
 196         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 197                 $this->forEachLB(
 198                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 199                                 call_user_func_array( [ $loadBalancer, $methodName ], $args );
 200                         },
 201                         [ $methodName, $args ]
 202                 );
 203         }
 204
 205         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 206                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 207         }
 208
 209         public function commitAll( $fname = __METHOD__, array $options = [] ) {
 210                 $this->commitMasterChanges( $fname, $options );
 211                 $this->forEachLBCallMethod( 'commitAll', [ $fname ] );
 212         }
 213
 214         public function beginMasterChanges( $fname = __METHOD__ ) {
 215                 if ( $this->trxRoundId !== false ) {
 216                         throw new DBTransactionError(
 217                                 null,
 218                                 "$fname: transaction round '{$this->trxRoundId}' already started."
 219                         );
 220                 }
 221                 $this->trxRoundId = $fname;
 222                 // Set DBO_TRX flags on all appropriate DBs
 223                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname ] );
 224         }
 225
 226         public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 227                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 228                         throw new DBTransactionError(
 229                                 null,
 230                                 "$fname: transaction round '{$this->trxRoundId}' still running."
 231                         );
 232                 }
 233                 /** @noinspection PhpUnusedLocalVariableInspection */
 234                 $scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
 235                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 236                 $this->forEachLBCallMethod( 'finalizeMasterChanges' );
 237                 $this->trxRoundId = false;
 238                 // Perform pre-commit checks, aborting on failure
 239                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] );
 240                 // Log the DBs and methods involved in multi-DB transactions
 241                 $this->logIfMultiDbTransaction();
 242                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 243                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 244                 // Run all post-commit callbacks
 245                 /** @var Exception $e */
 246                 $e = null; // first callback exception
 247                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
 248                         $ex = $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_COMMIT );
 249                         $e = $e ?: $ex;
 250                 } );
 251                 // Commit any dangling DBO_TRX transactions from callbacks on one DB to another DB
 252                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 253                 // Throw any last post-commit callback error
 254                 if ( $e instanceof Exception ) {
 255                         throw $e;
 256                 }
 257         }
 258
 259         public function rollbackMasterChanges( $fname = __METHOD__ ) {
 260                 $this->trxRoundId = false;
 261                 $this->forEachLBCallMethod( 'suppressTransactionEndCallbacks' );
 262                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] );
 263                 // Run all post-rollback callbacks
 264                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 265                         $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_ROLLBACK );
 266                 } );
 267         }
 268
 269         public function hasTransactionRound() {
 270                 return ( $this->trxRoundId !== false );
 271         }
 272
 273         /**
 274          * Log query info if multi DB transactions are going to be committed now
 275          */
 276         private function logIfMultiDbTransaction() {
 277                 $callersByDB = [];
 278                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 279                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 280                         $callers = $lb->pendingMasterChangeCallers();
 281                         if ( $callers ) {
 282                                 $callersByDB[$masterName] = $callers;
 283                         }
 284                 } );
 285
 286                 if ( count( $callersByDB ) >= 2 ) {
 287                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 288                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 289                         foreach ( $callersByDB as $db => $callers ) {
 290                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 291                         }
 292                         $this->queryLogger->info( $msg );
 293                 }
 294         }
 295
 296         public function hasMasterChanges() {
 297                 $ret = false;
 298                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 299                         $ret = $ret || $lb->hasMasterChanges();
 300                 } );
 301
 302                 return $ret;
 303         }
 304
 305         public function laggedReplicaUsed() {
 306                 $ret = false;
 307                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 308                         $ret = $ret || $lb->laggedReplicaUsed();
 309                 } );
 310
 311                 return $ret;
 312         }
 313
 314         public function hasOrMadeRecentMasterChanges( $age = null ) {
 315                 $ret = false;
 316                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 317                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 318                 } );
 319                 return $ret;
 320         }
 321
 322         public function waitForReplication( array $opts = [] ) {
 323                 $opts += [
 324                         'domain' => false,
 325                         'cluster' => false,
 326                         'timeout' => $this->cliMode ? 60 : 10,
 327                         'ifWritesSince' => null
 328                 ];
 329
 330                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 331                         $opts['domain'] = $opts['wiki']; // b/c
 332                 }
 333
 334                 // Figure out which clusters need to be checked
 335                 /** @var ILoadBalancer[] $lbs */
 336                 $lbs = [];
 337                 if ( $opts['cluster'] !== false ) {
 338                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 339                 } elseif ( $opts['domain'] !== false ) {
 340                         $lbs[] = $this->getMainLB( $opts['domain'] );
 341                 } else {
 342                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 343                                 $lbs[] = $lb;
 344                         } );
 345                         if ( !$lbs ) {
 346                                 return; // nothing actually used
 347                         }
 348                 }
 349
 350                 // Get all the master positions of applicable DBs right now.
 351                 // This can be faster since waiting on one cluster reduces the
 352                 // time needed to wait on the next clusters.
 353                 $masterPositions = array_fill( 0, count( $lbs ), false );
 354                 foreach ( $lbs as $i => $lb ) {
 355                         if ( $lb->getServerCount() <= 1 ) {
 356                                 // T29975 - Don't try to wait for replica DBs if there are none
 357                                 // Prevents permission error when getting master position
 358                                 continue;
 359                         } elseif ( $opts['ifWritesSince']
 360                                 && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 361                         ) {
 362                                 continue; // no writes since the last wait
 363                         }
 364                         $masterPositions[$i] = $lb->getMasterPos();
 365                 }
 366
 367                 // Run any listener callbacks *after* getting the DB positions. The more
 368                 // time spent in the callbacks, the less time is spent in waitForAll().
 369                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 370                         $callback();
 371                 }
 372
 373                 $failed = [];
 374                 foreach ( $lbs as $i => $lb ) {
 375                         if ( $masterPositions[$i] ) {
 376                                 // The RDBMS may not support getMasterPos()
 377                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 378                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 379                                 }
 380                         }
 381                 }
 382
 383                 if ( $failed ) {
 384                         throw new DBReplicationWaitError(
 385                                 null,
 386                                 "Could not wait for replica DBs to catch up to " .
 387                                 implode( ', ', $failed )
 388                         );
 389                 }
 390         }
 391
 392         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 393                 if ( $callback ) {
 394                         $this->replicationWaitCallbacks[$name] = $callback;
 395                 } else {
 396                         unset( $this->replicationWaitCallbacks[$name] );
 397                 }
 398         }
 399
 400         public function getEmptyTransactionTicket( $fname ) {
 401                 if ( $this->hasMasterChanges() ) {
 402                         $this->queryLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 403                                 ( new RuntimeException() )->getTraceAsString() );
 404
 405                         return null;
 406                 }
 407
 408                 return $this->ticket;
 409         }
 410
 411         public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 412                 if ( $ticket !== $this->ticket ) {
 413                         $this->perfLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 414                                 ( new RuntimeException() )->getTraceAsString() );
 415
 416                         return;
 417                 }
 418
 419                 // The transaction owner and any caller with the empty transaction ticket can commit
 420                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 421                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 422                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
 423                         $fnameEffective = $this->trxRoundId;
 424                 } else {
 425                         $fnameEffective = $fname;
 426                 }
 427
 428                 $this->commitMasterChanges( $fnameEffective );
 429                 $this->waitForReplication( $opts );
 430                 // If a nested caller committed on behalf of $fname, start another empty $fname
 431                 // transaction, leaving the caller with the same empty transaction state as before.
 432                 if ( $fnameEffective !== $fname ) {
 433                         $this->beginMasterChanges( $fnameEffective );
 434                 }
 435         }
 436
 437         public function getChronologyProtectorTouched( $dbName ) {
 438                 return $this->getChronologyProtector()->getTouched( $dbName );
 439         }
 440
 441         public function disableChronologyProtection() {
 442                 $this->getChronologyProtector()->setEnabled( false );
 443         }
 444
 445         /**
 446          * @return ChronologyProtector
 447          */
 448         protected function getChronologyProtector() {
 449                 if ( $this->chronProt ) {
 450                         return $this->chronProt;
 451                 }
 452
 453                 $this->chronProt = new ChronologyProtector(
 454                         $this->memStash,
 455                         [
 456                                 'ip' => $this->requestInfo['IPAddress'],
 457                                 'agent' => $this->requestInfo['UserAgent'],
 458                         ],
 459                         $this->requestInfo['ChronologyPositionIndex']
 460                 );
 461                 $this->chronProt->setLogger( $this->replLogger );
 462
 463                 if ( $this->cliMode ) {
 464                         $this->chronProt->setEnabled( false );
 465                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 466                         // Request opted out of using position wait logic. This is useful for requests
 467                         // done by the job queue or background ETL that do not have a meaningful session.
 468                         $this->chronProt->setWaitEnabled( false );
 469                 }
 470
 471                 $this->replLogger->debug( __METHOD__ . ': using request info ' .
 472                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT ) );
 473
 474                 return $this->chronProt;
 475         }
 476
 477         /**
 478          * Get and record all of the staged DB positions into persistent memory storage
 479          *
 480          * @param ChronologyProtector $cp
 481          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 482          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 483          * @param int|null &$cpIndex DB position key write counter; incremented on update
 484          */
 485         protected function shutdownChronologyProtector(
 486                 ChronologyProtector $cp, $workCallback, $mode, &$cpIndex = null
 487         ) {
 488                 // Record all the master positions needed
 489                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 490                         $cp->shutdownLB( $lb );
 491                 } );
 492                 // Write them to the persistent stash. Try to do something useful by running $work
 493                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 494                 $unsavedPositions = $cp->shutdown( $workCallback, $mode, $cpIndex );
 495                 if ( $unsavedPositions && $workCallback ) {
 496                         // Invoke callback in case it did not cache the result yet
 497                         $workCallback(); // work now to block for less time in waitForAll()
 498                 }
 499                 // If the positions failed to write to the stash, at least wait on local datacenter
 500                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 501                 // the chance that the user will see their own changes immediately afterwards. As long
 502                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 503                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 504                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 505                         if ( isset( $unsavedPositions[$masterName] ) ) {
 506                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 507                         }
 508                 } );
 509         }
 510
 511         /**
 512          * Base parameters to LoadBalancer::__construct()
 513          * @return array
 514          */
 515         final protected function baseLoadBalancerParams() {
 516                 return [
 517                         'localDomain' => $this->localDomain,
 518                         'readOnlyReason' => $this->readOnlyReason,
 519                         'srvCache' => $this->srvCache,
 520                         'wanCache' => $this->wanCache,
 521                         'profiler' => $this->profiler,
 522                         'trxProfiler' => $this->trxProfiler,
 523                         'queryLogger' => $this->queryLogger,
 524                         'connLogger' => $this->connLogger,
 525                         'replLogger' => $this->replLogger,
 526                         'errorLogger' => $this->errorLogger,
 527                         'deprecationLogger' => $this->deprecationLogger,
 528                         'hostname' => $this->hostname,
 529                         'cliMode' => $this->cliMode,
 530                         'agent' => $this->agent,
 531                         'chronologyCallback' => function ( ILoadBalancer $lb ) {
 532                                 // Defer ChronologyProtector construction in case setRequestInfo() ends up
 533                                 // being called later (but before the first connection attempt) (T192611)
 534                                 $this->getChronologyProtector()->initLB( $lb );
 535                         }
 536                 ];
 537         }
 538
 539         /**
 540          * @param ILoadBalancer $lb
 541          */
 542         protected function initLoadBalancer( ILoadBalancer $lb ) {
 543                 if ( $this->trxRoundId !== false ) {
 544                         $lb->beginMasterChanges( $this->trxRoundId ); // set DBO_TRX
 545                 }
 546
 547                 $lb->setTableAliases( $this->tableAliases );
 548                 $lb->setIndexAliases( $this->indexAliases );
 549         }
 550
 551         public function setTableAliases( array $aliases ) {
 552                 $this->tableAliases = $aliases;
 553         }
 554
 555         public function setIndexAliases( array $aliases ) {
 556                 $this->indexAliases = $aliases;
 557         }
 558
 559         public function setDomainPrefix( $prefix ) {
 560                 $this->localDomain = new DatabaseDomain(
 561                         $this->localDomain->getDatabase(),
 562                         null,
 563                         $prefix
 564                 );
 565
 566                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $prefix ) {
 567                         $lb->setDomainPrefix( $prefix );
 568                 } );
 569         }
 570
 571         public function closeAll() {
 572                 $this->forEachLBCallMethod( 'closeAll', [] );
 573         }
 574
 575         public function setAgentName( $agent ) {
 576                 $this->agent = $agent;
 577         }
 578
 579         public function appendShutdownCPIndexAsQuery( $url, $index ) {
 580                 $usedCluster = 0;
 581                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 582                         $usedCluster |= ( $lb->getServerCount() > 1 );
 583                 } );
 584
 585                 if ( !$usedCluster ) {
 586                         return $url; // no master/replica clusters touched
 587                 }
 588
 589                 return strpos( $url, '?' ) === false ? "$url?cpPosIndex=$index" : "$url&cpPosIndex=$index";
 590         }
 591
 592         public function setRequestInfo( array $info ) {
 593                 if ( $this->chronProt ) {
 594                         throw new LogicException( 'ChronologyProtector already initialized.' );
 595                 }
 596
 597                 $this->requestInfo = $info + $this->requestInfo;
 598         }
 599
 600         /**
 601          * Make PHP ignore user aborts/disconnects until the returned
 602          * value leaves scope. This returns null and does nothing in CLI mode.
 603          *
 604          * @return ScopedCallback|null
 605          */
 606         final protected function getScopedPHPBehaviorForCommit() {
 607                 if ( PHP_SAPI != 'cli' ) { // https://bugs.php.net/bug.php?id=47540
 608                         $old = ignore_user_abort( true ); // avoid half-finished operations
 609                         return new ScopedCallback( function () use ( $old ) {
 610                                 ignore_user_abort( $old );
 611                         } );
 612                 }
 613
 614                 return null;
 615         }
 616
 617         function __destruct() {
 618                 $this->destroy();
 619         }
 620 }
 621
 622 class_alias( LBFactory::class, 'LBFactory' );