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 use Psr\Log\LoggerInterface;
  25 use Wikimedia\ScopedCallback;
  26
  27 /**
  28  * An interface for generating database load balancers
  29  * @ingroup Database
  30  */
  31 abstract class LBFactory implements ILBFactory {
  32         /** @var ChronologyProtector */
  33         protected $chronProt;
  34         /** @var object|string Class name or object With profileIn/profileOut methods */
  35         protected $profiler;
  36         /** @var TransactionProfiler */
  37         protected $trxProfiler;
  38         /** @var LoggerInterface */
  39         protected $replLogger;
  40         /** @var LoggerInterface */
  41         protected $connLogger;
  42         /** @var LoggerInterface */
  43         protected $queryLogger;
  44         /** @var LoggerInterface */
  45         protected $perfLogger;
  46         /** @var callable Error logger */
  47         protected $errorLogger;
  48         /** @var BagOStuff */
  49         protected $srvCache;
  50         /** @var BagOStuff */
  51         protected $memCache;
  52         /** @var WANObjectCache */
  53         protected $wanCache;
  54
  55         /** @var DatabaseDomain Local domain */
  56         protected $localDomain;
  57         /** @var string Local hostname of the app server */
  58         protected $hostname;
  59         /** @var array Web request information about the client */
  60         protected $requestInfo;
  61
  62         /** @var bool[] Map of (section ID => true) for usage section IDs */
  63         protected $usageSections = [];
  64
  65         /** @var mixed */
  66         protected $ticket;
  67         /** @var string|bool String if a requested DBO_TRX transaction round is active */
  68         protected $trxRoundId = false;
  69         /** @var string|bool Reason all LBs are read-only or false if not */
  70         protected $readOnlyReason = false;
  71         /** @var callable[] */
  72         protected $replicationWaitCallbacks = [];
  73
  74         /** @var bool Whether this PHP instance is for a CLI script */
  75         protected $cliMode;
  76         /** @var string Agent name for query profiling */
  77         protected $agent;
  78
  79         private static $loggerFields =
  80                 [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];
  81
  82         public function __construct( array $conf ) {
  83                 $this->localDomain = isset( $conf['localDomain'] )
  84                         ? DatabaseDomain::newFromId( $conf['localDomain'] )
  85                         : DatabaseDomain::newUnspecified();
  86
  87                 if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
  88                         $this->readOnlyReason = $conf['readOnlyReason'];
  89                 }
  90
  91                 $this->srvCache = isset( $conf['srvCache'] ) ? $conf['srvCache'] : new EmptyBagOStuff();
  92                 $this->memCache = isset( $conf['memCache'] ) ? $conf['memCache'] : new EmptyBagOStuff();
  93                 $this->wanCache = isset( $conf['wanCache'] )
  94                         ? $conf['wanCache']
  95                         : WANObjectCache::newEmpty();
  96
  97                 foreach ( self::$loggerFields as $key ) {
  98                         $this->$key = isset( $conf[$key] ) ? $conf[$key] : new \Psr\Log\NullLogger();
  99                 }
 100                 $this->errorLogger = isset( $conf['errorLogger'] )
 101                         ? $conf['errorLogger']
 102                         : function ( Exception $e ) {
 103                                 trigger_error( E_USER_WARNING, get_class( $e ) . ': ' . $e->getMessage() );
 104                         };
 105
 106                 $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
 107                 $this->trxProfiler = isset( $conf['trxProfiler'] )
 108                         ? $conf['trxProfiler']
 109                         : new TransactionProfiler();
 110
 111                 $this->requestInfo = [
 112                         'IPAddress' => isset( $_SERVER[ 'REMOTE_ADDR' ] ) ? $_SERVER[ 'REMOTE_ADDR' ] : '',
 113                         'UserAgent' => isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : '',
 114                         'ChronologyProtection' => 'true'
 115                 ];
 116
 117                 $this->cliMode = isset( $params['cliMode'] ) ? $params['cliMode'] : PHP_SAPI === 'cli';
 118                 $this->hostname = isset( $conf['hostname'] ) ? $conf['hostname'] : gethostname();
 119                 $this->agent = isset( $params['agent'] ) ? $params['agent'] : '';
 120
 121                 $this->ticket = mt_rand();
 122         }
 123
 124         public function destroy() {
 125                 $this->shutdown( self::SHUTDOWN_NO_CHRONPROT );
 126                 $this->forEachLBCallMethod( 'disable' );
 127         }
 128
 129         public function shutdown(
 130                 $mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null
 131         ) {
 132                 $chronProt = $this->getChronologyProtector();
 133                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 134                         $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync' );
 135                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 136                         $this->shutdownChronologyProtector( $chronProt, null, 'async' );
 137                 }
 138
 139                 $this->commitMasterChanges( __METHOD__ ); // sanity
 140         }
 141
 142         /**
 143          * @see ILBFactory::newMainLB()
 144          * @param bool $domain
 145          * @return LoadBalancer
 146          */
 147         abstract public function newMainLB( $domain = false );
 148
 149         /**
 150          * @see ILBFactory::getMainLB()
 151          * @param bool $domain
 152          * @return LoadBalancer
 153          */
 154         abstract public function getMainLB( $domain = false );
 155
 156         /**
 157          * @see ILBFactory::newExternalLB()
 158          * @param string $cluster
 159          * @return LoadBalancer
 160          */
 161         abstract public function newExternalLB( $cluster );
 162
 163         /**
 164          * @see ILBFactory::getExternalLB()
 165          * @param string $cluster
 166          * @return LoadBalancer
 167          */
 168         abstract public function getExternalLB( $cluster );
 169
 170         /**
 171          * Call a method of each tracked load balancer
 172          *
 173          * @param string $methodName
 174          * @param array $args
 175          */
 176         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 177                 $this->forEachLB(
 178                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 179                                 call_user_func_array( [ $loadBalancer, $methodName ], $args );
 180                         },
 181                         [ $methodName, $args ]
 182                 );
 183         }
 184
 185         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 186                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 187         }
 188
 189         public function commitAll( $fname = __METHOD__, array $options = [] ) {
 190                 $this->commitMasterChanges( $fname, $options );
 191                 $this->forEachLBCallMethod( 'commitAll', [ $fname ] );
 192         }
 193
 194         public function beginMasterChanges( $fname = __METHOD__ ) {
 195                 if ( $this->trxRoundId !== false ) {
 196                         throw new DBTransactionError(
 197                                 null,
 198                                 "$fname: transaction round '{$this->trxRoundId}' already started."
 199                         );
 200                 }
 201                 $this->trxRoundId = $fname;
 202                 // Set DBO_TRX flags on all appropriate DBs
 203                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname ] );
 204         }
 205
 206         public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 207                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 208                         throw new DBTransactionError(
 209                                 null,
 210                                 "$fname: transaction round '{$this->trxRoundId}' still running."
 211                         );
 212                 }
 213                 /** @noinspection PhpUnusedLocalVariableInspection */
 214                 $scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
 215                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 216                 $this->forEachLBCallMethod( 'finalizeMasterChanges' );
 217                 $this->trxRoundId = false;
 218                 // Perform pre-commit checks, aborting on failure
 219                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] );
 220                 // Log the DBs and methods involved in multi-DB transactions
 221                 $this->logIfMultiDbTransaction();
 222                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 223                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 224                 // Run all post-commit callbacks
 225                 /** @var Exception $e */
 226                 $e = null; // first callback exception
 227                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
 228                         $ex = $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_COMMIT );
 229                         $e = $e ?: $ex;
 230                 } );
 231                 // Commit any dangling DBO_TRX transactions from callbacks on one DB to another DB
 232                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 233                 // Throw any last post-commit callback error
 234                 if ( $e instanceof Exception ) {
 235                         throw $e;
 236                 }
 237         }
 238
 239         public function rollbackMasterChanges( $fname = __METHOD__ ) {
 240                 $this->trxRoundId = false;
 241                 $this->forEachLBCallMethod( 'suppressTransactionEndCallbacks' );
 242                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] );
 243                 // Run all post-rollback callbacks
 244                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 245                         $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_ROLLBACK );
 246                 } );
 247         }
 248
 249         /**
 250          * Log query info if multi DB transactions are going to be committed now
 251          */
 252         private function logIfMultiDbTransaction() {
 253                 $callersByDB = [];
 254                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 255                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 256                         $callers = $lb->pendingMasterChangeCallers();
 257                         if ( $callers ) {
 258                                 $callersByDB[$masterName] = $callers;
 259                         }
 260                 } );
 261
 262                 if ( count( $callersByDB ) >= 2 ) {
 263                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 264                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 265                         foreach ( $callersByDB as $db => $callers ) {
 266                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 267                         }
 268                         $this->queryLogger->info( $msg );
 269                 }
 270         }
 271
 272         public function hasMasterChanges() {
 273                 $ret = false;
 274                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 275                         $ret = $ret || $lb->hasMasterChanges();
 276                 } );
 277
 278                 return $ret;
 279         }
 280
 281         public function laggedReplicaUsed() {
 282                 $ret = false;
 283                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 284                         $ret = $ret || $lb->laggedReplicaUsed();
 285                 } );
 286
 287                 return $ret;
 288         }
 289
 290         public function hasOrMadeRecentMasterChanges( $age = null ) {
 291                 $ret = false;
 292                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 293                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 294                 } );
 295                 return $ret;
 296         }
 297
 298         public function waitForReplication( array $opts = [] ) {
 299                 $opts += [
 300                         'domain' => false,
 301                         'cluster' => false,
 302                         'timeout' => 60,
 303                         'ifWritesSince' => null
 304                 ];
 305
 306                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 307                         $opts['domain'] = $opts['wiki']; // b/c
 308                 }
 309
 310                 // Figure out which clusters need to be checked
 311                 /** @var ILoadBalancer[] $lbs */
 312                 $lbs = [];
 313                 if ( $opts['cluster'] !== false ) {
 314                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 315                 } elseif ( $opts['domain'] !== false ) {
 316                         $lbs[] = $this->getMainLB( $opts['domain'] );
 317                 } else {
 318                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 319                                 $lbs[] = $lb;
 320                         } );
 321                         if ( !$lbs ) {
 322                                 return; // nothing actually used
 323                         }
 324                 }
 325
 326                 // Get all the master positions of applicable DBs right now.
 327                 // This can be faster since waiting on one cluster reduces the
 328                 // time needed to wait on the next clusters.
 329                 $masterPositions = array_fill( 0, count( $lbs ), false );
 330                 foreach ( $lbs as $i => $lb ) {
 331                         if ( $lb->getServerCount() <= 1 ) {
 332                                 // Bug 27975 - Don't try to wait for replica DBs if there are none
 333                                 // Prevents permission error when getting master position
 334                                 continue;
 335                         } elseif ( $opts['ifWritesSince']
 336                                 && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 337                         ) {
 338                                 continue; // no writes since the last wait
 339                         }
 340                         $masterPositions[$i] = $lb->getMasterPos();
 341                 }
 342
 343                 // Run any listener callbacks *after* getting the DB positions. The more
 344                 // time spent in the callbacks, the less time is spent in waitForAll().
 345                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 346                         $callback();
 347                 }
 348
 349                 $failed = [];
 350                 foreach ( $lbs as $i => $lb ) {
 351                         if ( $masterPositions[$i] ) {
 352                                 // The DBMS may not support getMasterPos()
 353                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 354                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 355                                 }
 356                         }
 357                 }
 358
 359                 if ( $failed ) {
 360                         throw new DBReplicationWaitError(
 361                                 null,
 362                                 "Could not wait for replica DBs to catch up to " .
 363                                 implode( ', ', $failed )
 364                         );
 365                 }
 366         }
 367
 368         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 369                 if ( $callback ) {
 370                         $this->replicationWaitCallbacks[$name] = $callback;
 371                 } else {
 372                         unset( $this->replicationWaitCallbacks[$name] );
 373                 }
 374         }
 375
 376         public function getEmptyTransactionTicket( $fname ) {
 377                 if ( $this->hasMasterChanges() ) {
 378                         $this->queryLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 379                                 ( new RuntimeException() )->getTraceAsString() );
 380
 381                         return null;
 382                 }
 383
 384                 return $this->ticket;
 385         }
 386
 387         public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 388                 if ( $ticket !== $this->ticket ) {
 389                         $this->perfLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 390                                 ( new RuntimeException() )->getTraceAsString() );
 391
 392                         return;
 393                 }
 394
 395                 // The transaction owner and any caller with the empty transaction ticket can commit
 396                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 397                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 398                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
 399                         $fnameEffective = $this->trxRoundId;
 400                 } else {
 401                         $fnameEffective = $fname;
 402                 }
 403
 404                 $this->commitMasterChanges( $fnameEffective );
 405                 $this->waitForReplication( $opts );
 406                 // If a nested caller committed on behalf of $fname, start another empty $fname
 407                 // transaction, leaving the caller with the same empty transaction state as before.
 408                 if ( $fnameEffective !== $fname ) {
 409                         $this->beginMasterChanges( $fnameEffective );
 410                 }
 411         }
 412
 413         public function getChronologyProtectorTouched( $dbName ) {
 414                 return $this->getChronologyProtector()->getTouched( $dbName );
 415         }
 416
 417         public function disableChronologyProtection() {
 418                 $this->getChronologyProtector()->setEnabled( false );
 419         }
 420
 421         /**
 422          * @return ChronologyProtector
 423          */
 424         protected function getChronologyProtector() {
 425                 if ( $this->chronProt ) {
 426                         return $this->chronProt;
 427                 }
 428
 429                 $this->chronProt = new ChronologyProtector(
 430                         $this->memCache,
 431                         [
 432                                 'ip' => $this->requestInfo['IPAddress'],
 433                                 'agent' => $this->requestInfo['UserAgent'],
 434                         ],
 435                         isset( $_GET['cpPosTime'] ) ? $_GET['cpPosTime'] : null
 436                 );
 437                 $this->chronProt->setLogger( $this->replLogger );
 438
 439                 if ( $this->cliMode ) {
 440                         $this->chronProt->setEnabled( false );
 441                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 442                         // Request opted out of using position wait logic. This is useful for requests
 443                         // done by the job queue or background ETL that do not have a meaningful session.
 444                         $this->chronProt->setWaitEnabled( false );
 445                 }
 446
 447                 $this->replLogger->debug( __METHOD__ . ': using request info ' .
 448                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT ) );
 449
 450                 return $this->chronProt;
 451         }
 452
 453         /**
 454          * Get and record all of the staged DB positions into persistent memory storage
 455          *
 456          * @param ChronologyProtector $cp
 457          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 458          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 459          */
 460         protected function shutdownChronologyProtector(
 461                 ChronologyProtector $cp, $workCallback, $mode
 462         ) {
 463                 // Record all the master positions needed
 464                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 465                         $cp->shutdownLB( $lb );
 466                 } );
 467                 // Write them to the persistent stash. Try to do something useful by running $work
 468                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 469                 $unsavedPositions = $cp->shutdown( $workCallback, $mode );
 470                 if ( $unsavedPositions && $workCallback ) {
 471                         // Invoke callback in case it did not cache the result yet
 472                         $workCallback(); // work now to block for less time in waitForAll()
 473                 }
 474                 // If the positions failed to write to the stash, at least wait on local datacenter
 475                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 476                 // the chance that the user will see their own changes immediately afterwards. As long
 477                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 478                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 479                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 480                         if ( isset( $unsavedPositions[$masterName] ) ) {
 481                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 482                         }
 483                 } );
 484         }
 485
 486         /**
 487          * Base parameters to LoadBalancer::__construct()
 488          * @return array
 489          */
 490         final protected function baseLoadBalancerParams() {
 491                 return [
 492                         'localDomain' => $this->localDomain,
 493                         'readOnlyReason' => $this->readOnlyReason,
 494                         'srvCache' => $this->srvCache,
 495                         'wanCache' => $this->wanCache,
 496                         'profiler' => $this->profiler,
 497                         'trxProfiler' => $this->trxProfiler,
 498                         'queryLogger' => $this->queryLogger,
 499                         'connLogger' => $this->connLogger,
 500                         'replLogger' => $this->replLogger,
 501                         'errorLogger' => $this->errorLogger,
 502                         'hostname' => $this->hostname,
 503                         'cliMode' => $this->cliMode,
 504                         'agent' => $this->agent
 505                 ];
 506         }
 507
 508         /**
 509          * Method called whenever a new LoadBalancer is created
 510          *
 511          * @param ILoadBalancer $lb
 512          */
 513         protected function initLoadBalancer( ILoadBalancer $lb ) {
 514                 if ( $this->trxRoundId !== false ) {
 515                         $lb->beginMasterChanges( $this->trxRoundId ); // set DBO_TRX
 516                 }
 517                 foreach ( $this->usageSections as $id => $unused ) {
 518                         $lb->declareUsageSectionStart( $id );
 519                 }
 520         }
 521
 522         public function setDomainPrefix( $prefix ) {
 523                 $this->localDomain = new DatabaseDomain(
 524                         $this->localDomain->getDatabase(),
 525                         null,
 526                         $prefix
 527                 );
 528
 529                 $this->forEachLB( function( ILoadBalancer $lb ) use ( $prefix ) {
 530                         $lb->setDomainPrefix( $prefix );
 531                 } );
 532         }
 533
 534         public function closeAll() {
 535                 $this->forEachLBCallMethod( 'closeAll', [] );
 536         }
 537
 538         public function setAgentName( $agent ) {
 539                 $this->agent = $agent;
 540         }
 541
 542         public function appendPreShutdownTimeAsQuery( $url, $time ) {
 543                 $usedCluster = 0;
 544                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 545                         $usedCluster |= ( $lb->getServerCount() > 1 );
 546                 } );
 547
 548                 if ( !$usedCluster ) {
 549                         return $url; // no master/replica clusters touched
 550                 }
 551
 552                 return strpos( $url, '?' ) === false ? "$url?cpPosTime=$time" : "$url&cpPosTime=$time";
 553         }
 554
 555         public function setRequestInfo( array $info ) {
 556                 $this->requestInfo = $info + $this->requestInfo;
 557         }
 558
 559         public function declareUsageSectionStart( $id = null ) {
 560                 static $nextId = 1;
 561                 if ( $id === null ) {
 562                         $id = $nextId;
 563                         ++$nextId;
 564                 }
 565                 // Handle existing load balancers
 566                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $id ) {
 567                         $lb->declareUsageSectionStart( $id );
 568                 } );
 569                 // Remember to set this for new load balancers
 570                 $this->usageSections[$id] = true;
 571
 572                 return $id;
 573         }
 574
 575         public function declareUsageSectionEnd( $id ) {
 576                 $info = [ 'readQueries' => 0, 'writeQueries' => 0, 'cacheSetOptions' => null ];
 577                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $id, &$info ) {
 578                         $lbInfo = $lb->declareUsageSectionEnd( $id );
 579                         $info['readQueries'] += $lbInfo['readQueries'];
 580                         $info['writeQueries'] += $lbInfo['writeQueries'];
 581                         $dbCacheOpts = $lbInfo['cacheSetOptions'];
 582                         if ( $dbCacheOpts ) {
 583                                 $info['cacheSetOptions'] = $info['cacheSetOptions']
 584                                         ? Database::mergeCacheSetOptions( $info['cacheSetOptions'], $dbCacheOpts )
 585                                         : $dbCacheOpts;
 586                         }
 587                 } );
 588                 unset( $this->usageSections[$id] );
 589
 590                 return $info;
 591         }
 592
 593         /**
 594          * Make PHP ignore user aborts/disconnects until the returned
 595          * value leaves scope. This returns null and does nothing in CLI mode.
 596          *
 597          * @return ScopedCallback|null
 598          */
 599         final protected function getScopedPHPBehaviorForCommit() {
 600                 if ( PHP_SAPI != 'cli' ) { // https://bugs.php.net/bug.php?id=47540
 601                         $old = ignore_user_abort( true ); // avoid half-finished operations
 602                         return new ScopedCallback( function () use ( $old ) {
 603                                 ignore_user_abort( $old );
 604                         } );
 605                 }
 606
 607                 return null;
 608         }
 609
 610         function __destruct() {
 611                 $this->destroy();
 612         }
 613 }