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         /** @var string One of the ROUND_* class constants */
  92         private $trxRoundStage = self::ROUND_CURSORY;
  93
  94         const ROUND_CURSORY = 'cursory';
  95         const ROUND_BEGINNING = 'within-begin';
  96         const ROUND_COMMITTING = 'within-commit';
  97         const ROUND_ROLLING_BACK = 'within-rollback';
  98
  99         private static $loggerFields =
 100                 [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];
 101
 102         public function __construct( array $conf ) {
 103                 $this->localDomain = isset( $conf['localDomain'] )
 104                         ? DatabaseDomain::newFromId( $conf['localDomain'] )
 105                         : DatabaseDomain::newUnspecified();
 106
 107                 if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
 108                         $this->readOnlyReason = $conf['readOnlyReason'];
 109                 }
 110
 111                 $this->srvCache = isset( $conf['srvCache'] ) ? $conf['srvCache'] : new EmptyBagOStuff();
 112                 $this->memStash = isset( $conf['memStash'] ) ? $conf['memStash'] : new EmptyBagOStuff();
 113                 $this->wanCache = isset( $conf['wanCache'] )
 114                         ? $conf['wanCache']
 115                         : WANObjectCache::newEmpty();
 116
 117                 foreach ( self::$loggerFields as $key ) {
 118                         $this->$key = isset( $conf[$key] ) ? $conf[$key] : new \Psr\Log\NullLogger();
 119                 }
 120                 $this->errorLogger = isset( $conf['errorLogger'] )
 121                         ? $conf['errorLogger']
 122                         : function ( Exception $e ) {
 123                                 trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 124                         };
 125                 $this->deprecationLogger = isset( $conf['deprecationLogger'] )
 126                         ? $conf['deprecationLogger']
 127                         : function ( $msg ) {
 128                                 trigger_error( $msg, E_USER_DEPRECATED );
 129                         };
 130
 131                 $this->profiler = isset( $conf['profiler'] ) ? $conf['profiler'] : null;
 132                 $this->trxProfiler = isset( $conf['trxProfiler'] )
 133                         ? $conf['trxProfiler']
 134                         : new TransactionProfiler();
 135
 136                 $this->requestInfo = [
 137                         'IPAddress' => isset( $_SERVER[ 'REMOTE_ADDR' ] ) ? $_SERVER[ 'REMOTE_ADDR' ] : '',
 138                         'UserAgent' => isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : '',
 139                         'ChronologyProtection' => 'true',
 140                         'ChronologyPositionIndex' => isset( $_GET['cpPosIndex'] ) ? $_GET['cpPosIndex'] : null
 141                 ];
 142
 143                 $this->cliMode = isset( $conf['cliMode'] )
 144                         ? $conf['cliMode']
 145                         : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 146                 $this->hostname = isset( $conf['hostname'] ) ? $conf['hostname'] : gethostname();
 147                 $this->agent = isset( $conf['agent'] ) ? $conf['agent'] : '';
 148
 149                 $this->ticket = mt_rand();
 150         }
 151
 152         public function destroy() {
 153                 $this->shutdown( self::SHUTDOWN_NO_CHRONPROT );
 154                 $this->forEachLBCallMethod( 'disable' );
 155         }
 156
 157         public function shutdown(
 158                 $mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null, &$cpIndex = null
 159         ) {
 160                 $chronProt = $this->getChronologyProtector();
 161                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 162                         $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync', $cpIndex );
 163                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 164                         $this->shutdownChronologyProtector( $chronProt, null, 'async', $cpIndex );
 165                 }
 166
 167                 $this->commitMasterChanges( __METHOD__ ); // sanity
 168         }
 169
 170         /**
 171          * @see ILBFactory::newMainLB()
 172          * @param bool $domain
 173          * @return LoadBalancer
 174          */
 175         abstract public function newMainLB( $domain = false );
 176
 177         /**
 178          * @see ILBFactory::getMainLB()
 179          * @param bool $domain
 180          * @return LoadBalancer
 181          */
 182         abstract public function getMainLB( $domain = false );
 183
 184         /**
 185          * @see ILBFactory::newExternalLB()
 186          * @param string $cluster
 187          * @return LoadBalancer
 188          */
 189         abstract public function newExternalLB( $cluster );
 190
 191         /**
 192          * @see ILBFactory::getExternalLB()
 193          * @param string $cluster
 194          * @return LoadBalancer
 195          */
 196         abstract public function getExternalLB( $cluster );
 197
 198         /**
 199          * Call a method of each tracked load balancer
 200          *
 201          * @param string $methodName
 202          * @param array $args
 203          */
 204         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 205                 $this->forEachLB(
 206                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 207                                 call_user_func_array( [ $loadBalancer, $methodName ], $args );
 208                         },
 209                         [ $methodName, $args ]
 210                 );
 211         }
 212
 213         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 214                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 215         }
 216
 217         final public function commitAll( $fname = __METHOD__, array $options = [] ) {
 218                 $this->commitMasterChanges( $fname, $options );
 219                 $this->forEachLBCallMethod( 'commitAll', [ $fname ] );
 220         }
 221
 222         final public function beginMasterChanges( $fname = __METHOD__ ) {
 223                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 224                 $this->trxRoundStage = self::ROUND_BEGINNING;
 225                 if ( $this->trxRoundId !== false ) {
 226                         throw new DBTransactionError(
 227                                 null,
 228                                 "$fname: transaction round '{$this->trxRoundId}' already started."
 229                         );
 230                 }
 231                 $this->trxRoundId = $fname;
 232                 // Set DBO_TRX flags on all appropriate DBs
 233                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname ] );
 234                 $this->trxRoundStage = self::ROUND_CURSORY;
 235         }
 236
 237         final public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 238                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 239                 $this->trxRoundStage = self::ROUND_COMMITTING;
 240                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 241                         throw new DBTransactionError(
 242                                 null,
 243                                 "$fname: transaction round '{$this->trxRoundId}' still running."
 244                         );
 245                 }
 246                 /** @noinspection PhpUnusedLocalVariableInspection */
 247                 $scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
 248                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 249                 do {
 250                         $count = 0; // number of callbacks executed this iteration
 251                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$count ) {
 252                                 $count += $lb->finalizeMasterChanges();
 253                         } );
 254                 } while ( $count > 0 );
 255                 $this->trxRoundId = false;
 256                 // Perform pre-commit checks, aborting on failure
 257                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] );
 258                 // Log the DBs and methods involved in multi-DB transactions
 259                 $this->logIfMultiDbTransaction();
 260                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 261                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 262                 // Run all post-commit callbacks in a separate step
 263                 $e = $this->executePostTransactionCallbacks();
 264                 $this->trxRoundStage = self::ROUND_CURSORY;
 265                 // Throw any last post-commit callback error
 266                 if ( $e instanceof Exception ) {
 267                         throw $e;
 268                 }
 269         }
 270
 271         final public function rollbackMasterChanges( $fname = __METHOD__ ) {
 272                 $this->trxRoundStage = self::ROUND_ROLLING_BACK;
 273                 $this->trxRoundId = false;
 274                 // Actually perform the rollback on all master DB connections and revert DBO_TRX
 275                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] );
 276                 // Run all post-commit callbacks in a separate step
 277                 $this->executePostTransactionCallbacks();
 278                 $this->trxRoundStage = self::ROUND_CURSORY;
 279         }
 280
 281         /**
 282          * @return Exception|null
 283          */
 284         private function executePostTransactionCallbacks() {
 285                 // Run all post-commit callbacks until new ones stop getting added
 286                 $e = null; // first callback exception
 287                 do {
 288                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
 289                                 $ex = $lb->runMasterTransactionIdleCallbacks();
 290                                 $e = $e ?: $ex;
 291                         } );
 292                 } while ( $this->hasMasterChanges() );
 293                 // Run all listener callbacks once
 294                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
 295                         $ex = $lb->runMasterTransactionListenerCallbacks();
 296                         $e = $e ?: $ex;
 297                 } );
 298
 299                 return $e;
 300         }
 301
 302         public function hasTransactionRound() {
 303                 return ( $this->trxRoundId !== false );
 304         }
 305
 306         public function isReadyForRoundOperations() {
 307                 return ( $this->trxRoundStage === self::ROUND_CURSORY );
 308         }
 309
 310         /**
 311          * Log query info if multi DB transactions are going to be committed now
 312          */
 313         private function logIfMultiDbTransaction() {
 314                 $callersByDB = [];
 315                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 316                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 317                         $callers = $lb->pendingMasterChangeCallers();
 318                         if ( $callers ) {
 319                                 $callersByDB[$masterName] = $callers;
 320                         }
 321                 } );
 322
 323                 if ( count( $callersByDB ) >= 2 ) {
 324                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 325                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 326                         foreach ( $callersByDB as $db => $callers ) {
 327                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 328                         }
 329                         $this->queryLogger->info( $msg );
 330                 }
 331         }
 332
 333         public function hasMasterChanges() {
 334                 $ret = false;
 335                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 336                         $ret = $ret || $lb->hasMasterChanges();
 337                 } );
 338
 339                 return $ret;
 340         }
 341
 342         public function laggedReplicaUsed() {
 343                 $ret = false;
 344                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 345                         $ret = $ret || $lb->laggedReplicaUsed();
 346                 } );
 347
 348                 return $ret;
 349         }
 350
 351         public function hasOrMadeRecentMasterChanges( $age = null ) {
 352                 $ret = false;
 353                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 354                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 355                 } );
 356                 return $ret;
 357         }
 358
 359         public function waitForReplication( array $opts = [] ) {
 360                 $opts += [
 361                         'domain' => false,
 362                         'cluster' => false,
 363                         'timeout' => $this->cliMode ? 60 : 10,
 364                         'ifWritesSince' => null
 365                 ];
 366
 367                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 368                         $opts['domain'] = $opts['wiki']; // b/c
 369                 }
 370
 371                 // Figure out which clusters need to be checked
 372                 /** @var ILoadBalancer[] $lbs */
 373                 $lbs = [];
 374                 if ( $opts['cluster'] !== false ) {
 375                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 376                 } elseif ( $opts['domain'] !== false ) {
 377                         $lbs[] = $this->getMainLB( $opts['domain'] );
 378                 } else {
 379                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 380                                 $lbs[] = $lb;
 381                         } );
 382                         if ( !$lbs ) {
 383                                 return; // nothing actually used
 384                         }
 385                 }
 386
 387                 // Get all the master positions of applicable DBs right now.
 388                 // This can be faster since waiting on one cluster reduces the
 389                 // time needed to wait on the next clusters.
 390                 $masterPositions = array_fill( 0, count( $lbs ), false );
 391                 foreach ( $lbs as $i => $lb ) {
 392                         if ( $lb->getServerCount() <= 1 ) {
 393                                 // T29975 - Don't try to wait for replica DBs if there are none
 394                                 // Prevents permission error when getting master position
 395                                 continue;
 396                         } elseif ( $opts['ifWritesSince']
 397                                 && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 398                         ) {
 399                                 continue; // no writes since the last wait
 400                         }
 401                         $masterPositions[$i] = $lb->getMasterPos();
 402                 }
 403
 404                 // Run any listener callbacks *after* getting the DB positions. The more
 405                 // time spent in the callbacks, the less time is spent in waitForAll().
 406                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 407                         $callback();
 408                 }
 409
 410                 $failed = [];
 411                 foreach ( $lbs as $i => $lb ) {
 412                         if ( $masterPositions[$i] ) {
 413                                 // The RDBMS may not support getMasterPos()
 414                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 415                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 416                                 }
 417                         }
 418                 }
 419
 420                 if ( $failed ) {
 421                         throw new DBReplicationWaitError(
 422                                 null,
 423                                 "Could not wait for replica DBs to catch up to " .
 424                                 implode( ', ', $failed )
 425                         );
 426                 }
 427         }
 428
 429         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 430                 if ( $callback ) {
 431                         $this->replicationWaitCallbacks[$name] = $callback;
 432                 } else {
 433                         unset( $this->replicationWaitCallbacks[$name] );
 434                 }
 435         }
 436
 437         public function getEmptyTransactionTicket( $fname ) {
 438                 if ( $this->hasMasterChanges() ) {
 439                         $this->queryLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 440                                 ( new RuntimeException() )->getTraceAsString() );
 441
 442                         return null;
 443                 }
 444
 445                 return $this->ticket;
 446         }
 447
 448         final public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 449                 if ( $ticket !== $this->ticket ) {
 450                         $this->perfLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 451                                 ( new RuntimeException() )->getTraceAsString() );
 452
 453                         return;
 454                 }
 455
 456                 // The transaction owner and any caller with the empty transaction ticket can commit
 457                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 458                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 459                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
 460                         $fnameEffective = $this->trxRoundId;
 461                 } else {
 462                         $fnameEffective = $fname;
 463                 }
 464
 465                 $this->commitMasterChanges( $fnameEffective );
 466                 $this->waitForReplication( $opts );
 467                 // If a nested caller committed on behalf of $fname, start another empty $fname
 468                 // transaction, leaving the caller with the same empty transaction state as before.
 469                 if ( $fnameEffective !== $fname ) {
 470                         $this->beginMasterChanges( $fnameEffective );
 471                 }
 472         }
 473
 474         public function getChronologyProtectorTouched( $dbName ) {
 475                 return $this->getChronologyProtector()->getTouched( $dbName );
 476         }
 477
 478         public function disableChronologyProtection() {
 479                 $this->getChronologyProtector()->setEnabled( false );
 480         }
 481
 482         /**
 483          * @return ChronologyProtector
 484          */
 485         protected function getChronologyProtector() {
 486                 if ( $this->chronProt ) {
 487                         return $this->chronProt;
 488                 }
 489
 490                 $this->chronProt = new ChronologyProtector(
 491                         $this->memStash,
 492                         [
 493                                 'ip' => $this->requestInfo['IPAddress'],
 494                                 'agent' => $this->requestInfo['UserAgent'],
 495                         ],
 496                         $this->requestInfo['ChronologyPositionIndex']
 497                 );
 498                 $this->chronProt->setLogger( $this->replLogger );
 499
 500                 if ( $this->cliMode ) {
 501                         $this->chronProt->setEnabled( false );
 502                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 503                         // Request opted out of using position wait logic. This is useful for requests
 504                         // done by the job queue or background ETL that do not have a meaningful session.
 505                         $this->chronProt->setWaitEnabled( false );
 506                 }
 507
 508                 $this->replLogger->debug( __METHOD__ . ': using request info ' .
 509                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT ) );
 510
 511                 return $this->chronProt;
 512         }
 513
 514         /**
 515          * Get and record all of the staged DB positions into persistent memory storage
 516          *
 517          * @param ChronologyProtector $cp
 518          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 519          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 520          * @param int|null &$cpIndex DB position key write counter; incremented on update
 521          */
 522         protected function shutdownChronologyProtector(
 523                 ChronologyProtector $cp, $workCallback, $mode, &$cpIndex = null
 524         ) {
 525                 // Record all the master positions needed
 526                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 527                         $cp->shutdownLB( $lb );
 528                 } );
 529                 // Write them to the persistent stash. Try to do something useful by running $work
 530                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 531                 $unsavedPositions = $cp->shutdown( $workCallback, $mode, $cpIndex );
 532                 if ( $unsavedPositions && $workCallback ) {
 533                         // Invoke callback in case it did not cache the result yet
 534                         $workCallback(); // work now to block for less time in waitForAll()
 535                 }
 536                 // If the positions failed to write to the stash, at least wait on local datacenter
 537                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 538                 // the chance that the user will see their own changes immediately afterwards. As long
 539                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 540                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 541                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 542                         if ( isset( $unsavedPositions[$masterName] ) ) {
 543                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 544                         }
 545                 } );
 546         }
 547
 548         /**
 549          * Base parameters to LoadBalancer::__construct()
 550          * @return array
 551          */
 552         final protected function baseLoadBalancerParams() {
 553                 return [
 554                         'localDomain' => $this->localDomain,
 555                         'readOnlyReason' => $this->readOnlyReason,
 556                         'srvCache' => $this->srvCache,
 557                         'wanCache' => $this->wanCache,
 558                         'profiler' => $this->profiler,
 559                         'trxProfiler' => $this->trxProfiler,
 560                         'queryLogger' => $this->queryLogger,
 561                         'connLogger' => $this->connLogger,
 562                         'replLogger' => $this->replLogger,
 563                         'errorLogger' => $this->errorLogger,
 564                         'deprecationLogger' => $this->deprecationLogger,
 565                         'hostname' => $this->hostname,
 566                         'cliMode' => $this->cliMode,
 567                         'agent' => $this->agent,
 568                         'chronologyCallback' => function ( ILoadBalancer $lb ) {
 569                                 // Defer ChronologyProtector construction in case setRequestInfo() ends up
 570                                 // being called later (but before the first connection attempt) (T192611)
 571                                 $this->getChronologyProtector()->initLB( $lb );
 572                         }
 573                 ];
 574         }
 575
 576         /**
 577          * @param ILoadBalancer $lb
 578          */
 579         protected function initLoadBalancer( ILoadBalancer $lb ) {
 580                 if ( $this->trxRoundId !== false ) {
 581                         $lb->beginMasterChanges( $this->trxRoundId ); // set DBO_TRX
 582                 }
 583
 584                 $lb->setTableAliases( $this->tableAliases );
 585                 $lb->setIndexAliases( $this->indexAliases );
 586         }
 587
 588         public function setTableAliases( array $aliases ) {
 589                 $this->tableAliases = $aliases;
 590         }
 591
 592         public function setIndexAliases( array $aliases ) {
 593                 $this->indexAliases = $aliases;
 594         }
 595
 596         public function setDomainPrefix( $prefix ) {
 597                 $this->localDomain = new DatabaseDomain(
 598                         $this->localDomain->getDatabase(),
 599                         null,
 600                         $prefix
 601                 );
 602
 603                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $prefix ) {
 604                         $lb->setDomainPrefix( $prefix );
 605                 } );
 606         }
 607
 608         public function closeAll() {
 609                 $this->forEachLBCallMethod( 'closeAll', [] );
 610         }
 611
 612         public function setAgentName( $agent ) {
 613                 $this->agent = $agent;
 614         }
 615
 616         public function appendShutdownCPIndexAsQuery( $url, $index ) {
 617                 $usedCluster = 0;
 618                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 619                         $usedCluster |= ( $lb->getServerCount() > 1 );
 620                 } );
 621
 622                 if ( !$usedCluster ) {
 623                         return $url; // no master/replica clusters touched
 624                 }
 625
 626                 return strpos( $url, '?' ) === false ? "$url?cpPosIndex=$index" : "$url&cpPosIndex=$index";
 627         }
 628
 629         public function setRequestInfo( array $info ) {
 630                 if ( $this->chronProt ) {
 631                         throw new LogicException( 'ChronologyProtector already initialized.' );
 632                 }
 633
 634                 $this->requestInfo = $info + $this->requestInfo;
 635         }
 636
 637         /**
 638          * @param string $stage
 639          */
 640         private function assertTransactionRoundStage( $stage ) {
 641                 if ( $this->trxRoundStage !== $stage ) {
 642                         throw new DBTransactionError(
 643                                 null,
 644                                 "Transaction round stage must be '$stage' (not '{$this->trxRoundStage}')"
 645                         );
 646                 }
 647         }
 648
 649         /**
 650          * Make PHP ignore user aborts/disconnects until the returned
 651          * value leaves scope. This returns null and does nothing in CLI mode.
 652          *
 653          * @return ScopedCallback|null
 654          */
 655         final protected function getScopedPHPBehaviorForCommit() {
 656                 if ( PHP_SAPI != 'cli' ) { // https://bugs.php.net/bug.php?id=47540
 657                         $old = ignore_user_abort( true ); // avoid half-finished operations
 658                         return new ScopedCallback( function () use ( $old ) {
 659                                 ignore_user_abort( $old );
 660                         } );
 661                 }
 662
 663                 return null;
 664         }
 665
 666         function __destruct() {
 667                 $this->destroy();
 668         }
 669 }
 670
 671 class_alias( LBFactory::class, 'LBFactory' );