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