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
  26 /**
  27  * An interface for generating database load balancers
  28  * @ingroup Database
  29  */
  30 abstract class LBFactory {
  31         /** @var ChronologyProtector */
  32         protected $chronProt;
  33         /** @var TransactionProfiler */
  34         protected $trxProfiler;
  35         /** @var LoggerInterface */
  36         protected $replLogger;
  37         /** @var LoggerInterface */
  38         protected $connLogger;
  39         /** @var LoggerInterface */
  40         protected $queryLogger;
  41         /** @var LoggerInterface */
  42         protected $perfLogger;
  43         /** @var callable Error logger */
  44         protected $errorLogger;
  45         /** @var BagOStuff */
  46         protected $srvCache;
  47         /** @var BagOStuff */
  48         protected $memCache;
  49         /** @var WANObjectCache */
  50         protected $wanCache;
  51
  52         /** @var string Local domain */
  53         protected $domain;
  54         /** @var string Local hostname of the app server */
  55         protected $hostname;
  56         /** @var mixed */
  57         protected $ticket;
  58         /** @var string|bool String if a requested DBO_TRX transaction round is active */
  59         protected $trxRoundId = false;
  60         /** @var string|bool Reason all LBs are read-only or false if not */
  61         protected $readOnlyReason = false;
  62         /** @var callable[] */
  63         protected $replicationWaitCallbacks = [];
  64
  65         const SHUTDOWN_NO_CHRONPROT = 0; // don't save DB positions at all
  66         const SHUTDOWN_CHRONPROT_ASYNC = 1; // save DB positions, but don't wait on remote DCs
  67         const SHUTDOWN_CHRONPROT_SYNC = 2; // save DB positions, waiting on all DCs
  68
  69         private static $loggerFields =
  70                 [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];
  71
  72         /**
  73          * @TODO: document base params here
  74          * @param array $conf
  75          */
  76         public function __construct( array $conf ) {
  77                 $this->domain = isset( $conf['domain'] ) ? $conf['domain'] : '';
  78                 if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
  79                         $this->readOnlyReason = $conf['readOnlyReason'];
  80                 }
  81
  82                 $this->srvCache = isset( $conf['srvCache'] ) ? $conf['srvCache'] : new EmptyBagOStuff();
  83                 $this->memCache = isset( $conf['memCache'] ) ? $conf['memCache'] : new EmptyBagOStuff();
  84                 $this->wanCache = isset( $conf['wanCache'] )
  85                         ? $conf['wanCache']
  86                         : WANObjectCache::newEmpty();
  87
  88                 foreach ( self::$loggerFields as $key ) {
  89                         $this->$key = isset( $conf[$key] ) ? $conf[$key] : new \Psr\Log\NullLogger();
  90                 }
  91                 $this->errorLogger = isset( $conf['errorLogger'] )
  92                         ? $conf['errorLogger']
  93                         : function ( Exception $e ) {
  94                                 trigger_error( E_WARNING, $e->getMessage() );
  95                         };
  96                 $this->hostname = isset( $conf['hostname'] )
  97                         ? $conf['hostname']
  98                         : gethostname();
  99
 100                 $this->chronProt = isset( $conf['chronProt'] )
 101                         ? $conf['chronProt']
 102                         : $this->newChronologyProtector();
 103                 $this->trxProfiler = isset( $conf['trxProfiler'] )
 104                         ? $conf['trxProfiler']
 105                         : new TransactionProfiler();
 106
 107                 $this->ticket = mt_rand();
 108         }
 109
 110         /**
 111          * Disables all load balancers. All connections are closed, and any attempt to
 112          * open a new connection will result in a DBAccessError.
 113          * @see LoadBalancer::disable()
 114          */
 115         public function destroy() {
 116                 $this->shutdown( self::SHUTDOWN_NO_CHRONPROT );
 117                 $this->forEachLBCallMethod( 'disable' );
 118         }
 119
 120         /**
 121          * Create a new load balancer object. The resulting object will be untracked,
 122          * not chronology-protected, and the caller is responsible for cleaning it up.
 123          *
 124          * @param bool|string $domain Wiki ID, or false for the current wiki
 125          * @return ILoadBalancer
 126          */
 127         abstract public function newMainLB( $domain = false );
 128
 129         /**
 130          * Get a cached (tracked) load balancer object.
 131          *
 132          * @param bool|string $domain Wiki ID, or false for the current wiki
 133          * @return ILoadBalancer
 134          */
 135         abstract public function getMainLB( $domain = false );
 136
 137         /**
 138          * Create a new load balancer for external storage. The resulting object will be
 139          * untracked, not chronology-protected, and the caller is responsible for
 140          * cleaning it up.
 141          *
 142          * @param string $cluster External storage cluster, or false for core
 143          * @param bool|string $domain Wiki ID, or false for the current wiki
 144          * @return ILoadBalancer
 145          */
 146         abstract protected function newExternalLB( $cluster, $domain = false );
 147
 148         /**
 149          * Get a cached (tracked) load balancer for external storage
 150          *
 151          * @param string $cluster External storage cluster, or false for core
 152          * @param bool|string $domain Wiki ID, or false for the current wiki
 153          * @return ILoadBalancer
 154          */
 155         abstract public function getExternalLB( $cluster, $domain = false );
 156
 157         /**
 158          * Execute a function for each tracked load balancer
 159          * The callback is called with the load balancer as the first parameter,
 160          * and $params passed as the subsequent parameters.
 161          *
 162          * @param callable $callback
 163          * @param array $params
 164          */
 165         abstract public function forEachLB( $callback, array $params = [] );
 166
 167         /**
 168          * Prepare all tracked load balancers for shutdown
 169          * @param integer $mode One of the class SHUTDOWN_* constants
 170          * @param callable|null $workCallback Work to mask ChronologyProtector writes
 171          */
 172         public function shutdown(
 173                 $mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null
 174         ) {
 175                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 176                         $this->shutdownChronologyProtector( $this->chronProt, $workCallback, 'sync' );
 177                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 178                         $this->shutdownChronologyProtector( $this->chronProt, null, 'async' );
 179                 }
 180
 181                 $this->commitMasterChanges( __METHOD__ ); // sanity
 182         }
 183
 184         /**
 185          * Call a method of each tracked load balancer
 186          *
 187          * @param string $methodName
 188          * @param array $args
 189          */
 190         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 191                 $this->forEachLB(
 192                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 193                                 call_user_func_array( [ $loadBalancer, $methodName ], $args );
 194                         },
 195                         [ $methodName, $args ]
 196                 );
 197         }
 198
 199         /**
 200          * Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot
 201          *
 202          * @param string $fname Caller name
 203          * @since 1.28
 204          */
 205         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 206                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 207         }
 208
 209         /**
 210          * Commit on all connections. Done for two reasons:
 211          * 1. To commit changes to the masters.
 212          * 2. To release the snapshot on all connections, master and replica DB.
 213          * @param string $fname Caller name
 214          * @param array $options Options map:
 215          *   - maxWriteDuration: abort if more than this much time was spent in write queries
 216          */
 217         public function commitAll( $fname = __METHOD__, array $options = [] ) {
 218                 $this->commitMasterChanges( $fname, $options );
 219                 $this->forEachLBCallMethod( 'commitAll', [ $fname ] );
 220         }
 221
 222         /**
 223          * Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set)
 224          *
 225          * The DBO_TRX setting will be reverted to the default in each of these methods:
 226          *   - commitMasterChanges()
 227          *   - rollbackMasterChanges()
 228          *   - commitAll()
 229          *
 230          * This allows for custom transaction rounds from any outer transaction scope.
 231          *
 232          * @param string $fname
 233          * @throws DBTransactionError
 234          * @since 1.28
 235          */
 236         public function beginMasterChanges( $fname = __METHOD__ ) {
 237                 if ( $this->trxRoundId !== false ) {
 238                         throw new DBTransactionError(
 239                                 null,
 240                                 "$fname: transaction round '{$this->trxRoundId}' already started."
 241                         );
 242                 }
 243                 $this->trxRoundId = $fname;
 244                 // Set DBO_TRX flags on all appropriate DBs
 245                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname ] );
 246         }
 247
 248         /**
 249          * Commit changes on all master connections
 250          * @param string $fname Caller name
 251          * @param array $options Options map:
 252          *   - maxWriteDuration: abort if more than this much time was spent in write queries
 253          * @throws Exception
 254          */
 255         public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 256                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 257                         throw new DBTransactionError(
 258                                 null,
 259                                 "$fname: transaction round '{$this->trxRoundId}' still running."
 260                         );
 261                 }
 262                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 263                 $this->forEachLBCallMethod( 'finalizeMasterChanges' );
 264                 $this->trxRoundId = false;
 265                 // Perform pre-commit checks, aborting on failure
 266                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] );
 267                 // Log the DBs and methods involved in multi-DB transactions
 268                 $this->logIfMultiDbTransaction();
 269                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 270                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 271                 // Run all post-commit callbacks
 272                 /** @var Exception $e */
 273                 $e = null; // first callback exception
 274                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
 275                         $ex = $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_COMMIT );
 276                         $e = $e ?: $ex;
 277                 } );
 278                 // Commit any dangling DBO_TRX transactions from callbacks on one DB to another DB
 279                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 280                 // Throw any last post-commit callback error
 281                 if ( $e instanceof Exception ) {
 282                         throw $e;
 283                 }
 284         }
 285
 286         /**
 287          * Rollback changes on all master connections
 288          * @param string $fname Caller name
 289          * @since 1.23
 290          */
 291         public function rollbackMasterChanges( $fname = __METHOD__ ) {
 292                 $this->trxRoundId = false;
 293                 $this->forEachLBCallMethod( 'suppressTransactionEndCallbacks' );
 294                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] );
 295                 // Run all post-rollback callbacks
 296                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 297                         $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_ROLLBACK );
 298                 } );
 299         }
 300
 301         /**
 302          * Log query info if multi DB transactions are going to be committed now
 303          */
 304         private function logIfMultiDbTransaction() {
 305                 $callersByDB = [];
 306                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 307                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 308                         $callers = $lb->pendingMasterChangeCallers();
 309                         if ( $callers ) {
 310                                 $callersByDB[$masterName] = $callers;
 311                         }
 312                 } );
 313
 314                 if ( count( $callersByDB ) >= 2 ) {
 315                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 316                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 317                         foreach ( $callersByDB as $db => $callers ) {
 318                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 319                         }
 320                         $this->queryLogger->info( $msg );
 321                 }
 322         }
 323
 324         /**
 325          * Determine if any master connection has pending changes
 326          * @return bool
 327          * @since 1.23
 328          */
 329         public function hasMasterChanges() {
 330                 $ret = false;
 331                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 332                         $ret = $ret || $lb->hasMasterChanges();
 333                 } );
 334
 335                 return $ret;
 336         }
 337
 338         /**
 339          * Detemine if any lagged replica DB connection was used
 340          * @return bool
 341          * @since 1.28
 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         /**
 353          * Determine if any master connection has pending/written changes from this request
 354          * @param float $age How many seconds ago is "recent" [defaults to LB lag wait timeout]
 355          * @return bool
 356          * @since 1.27
 357          */
 358         public function hasOrMadeRecentMasterChanges( $age = null ) {
 359                 $ret = false;
 360                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 361                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 362                 } );
 363                 return $ret;
 364         }
 365
 366         /**
 367          * Waits for the replica DBs to catch up to the current master position
 368          *
 369          * Use this when updating very large numbers of rows, as in maintenance scripts,
 370          * to avoid causing too much lag. Of course, this is a no-op if there are no replica DBs.
 371          *
 372          * By default this waits on all DB clusters actually used in this request.
 373          * This makes sense when lag being waiting on is caused by the code that does this check.
 374          * In that case, setting "ifWritesSince" can avoid the overhead of waiting for clusters
 375          * that were not changed since the last wait check. To forcefully wait on a specific cluster
 376          * for a given wiki, use the 'wiki' parameter. To forcefully wait on an "external" cluster,
 377          * use the "cluster" parameter.
 378          *
 379          * Never call this function after a large DB write that is *still* in a transaction.
 380          * It only makes sense to call this after the possible lag inducing changes were committed.
 381          *
 382          * @param array $opts Optional fields that include:
 383          *   - wiki : wait on the load balancer DBs that handles the given wiki
 384          *   - cluster : wait on the given external load balancer DBs
 385          *   - timeout : Max wait time. Default: ~60 seconds
 386          *   - ifWritesSince: Only wait if writes were done since this UNIX timestamp
 387          * @throws DBReplicationWaitError If a timeout or error occured waiting on a DB cluster
 388          * @since 1.27
 389          */
 390         public function waitForReplication( array $opts = [] ) {
 391                 $opts += [
 392                         'wiki' => false,
 393                         'cluster' => false,
 394                         'timeout' => 60,
 395                         'ifWritesSince' => null
 396                 ];
 397
 398                 // Figure out which clusters need to be checked
 399                 /** @var ILoadBalancer[] $lbs */
 400                 $lbs = [];
 401                 if ( $opts['cluster'] !== false ) {
 402                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 403                 } elseif ( $opts['wiki'] !== false ) {
 404                         $lbs[] = $this->getMainLB( $opts['wiki'] );
 405                 } else {
 406                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 407                                 $lbs[] = $lb;
 408                         } );
 409                         if ( !$lbs ) {
 410                                 return; // nothing actually used
 411                         }
 412                 }
 413
 414                 // Get all the master positions of applicable DBs right now.
 415                 // This can be faster since waiting on one cluster reduces the
 416                 // time needed to wait on the next clusters.
 417                 $masterPositions = array_fill( 0, count( $lbs ), false );
 418                 foreach ( $lbs as $i => $lb ) {
 419                         if ( $lb->getServerCount() <= 1 ) {
 420                                 // Bug 27975 - Don't try to wait for replica DBs if there are none
 421                                 // Prevents permission error when getting master position
 422                                 continue;
 423                         } elseif ( $opts['ifWritesSince']
 424                                 && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 425                         ) {
 426                                 continue; // no writes since the last wait
 427                         }
 428                         $masterPositions[$i] = $lb->getMasterPos();
 429                 }
 430
 431                 // Run any listener callbacks *after* getting the DB positions. The more
 432                 // time spent in the callbacks, the less time is spent in waitForAll().
 433                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 434                         $callback();
 435                 }
 436
 437                 $failed = [];
 438                 foreach ( $lbs as $i => $lb ) {
 439                         if ( $masterPositions[$i] ) {
 440                                 // The DBMS may not support getMasterPos() or the whole
 441                                 // load balancer might be fake (e.g. $wgAllDBsAreLocalhost).
 442                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 443                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 444                                 }
 445                         }
 446                 }
 447
 448                 if ( $failed ) {
 449                         throw new DBReplicationWaitError(
 450                                 "Could not wait for replica DBs to catch up to " .
 451                                 implode( ', ', $failed )
 452                         );
 453                 }
 454         }
 455
 456         /**
 457          * Add a callback to be run in every call to waitForReplication() before waiting
 458          *
 459          * Callbacks must clear any transactions that they start
 460          *
 461          * @param string $name Callback name
 462          * @param callable|null $callback Use null to unset a callback
 463          * @since 1.28
 464          */
 465         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 466                 if ( $callback ) {
 467                         $this->replicationWaitCallbacks[$name] = $callback;
 468                 } else {
 469                         unset( $this->replicationWaitCallbacks[$name] );
 470                 }
 471         }
 472
 473         /**
 474          * Get a token asserting that no transaction writes are active
 475          *
 476          * @param string $fname Caller name (e.g. __METHOD__)
 477          * @return mixed A value to pass to commitAndWaitForReplication()
 478          * @since 1.28
 479          */
 480         public function getEmptyTransactionTicket( $fname ) {
 481                 if ( $this->hasMasterChanges() ) {
 482                         $this->queryLogger->error( __METHOD__ . ": $fname does not have outer scope." );
 483                         return null;
 484                 }
 485
 486                 return $this->ticket;
 487         }
 488
 489         /**
 490          * Convenience method for safely running commitMasterChanges()/waitForReplication()
 491          *
 492          * This will commit and wait unless $ticket indicates it is unsafe to do so
 493          *
 494          * @param string $fname Caller name (e.g. __METHOD__)
 495          * @param mixed $ticket Result of getEmptyTransactionTicket()
 496          * @param array $opts Options to waitForReplication()
 497          * @throws DBReplicationWaitError
 498          * @since 1.28
 499          */
 500         public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 501                 if ( $ticket !== $this->ticket ) {
 502                         $this->perfLogger->error( __METHOD__ . ": $fname does not have outer scope." );
 503                         return;
 504                 }
 505
 506                 // The transaction owner and any caller with the empty transaction ticket can commit
 507                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 508                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 509                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
 510                         $fnameEffective = $this->trxRoundId;
 511                 } else {
 512                         $fnameEffective = $fname;
 513                 }
 514
 515                 $this->commitMasterChanges( $fnameEffective );
 516                 $this->waitForReplication( $opts );
 517                 // If a nested caller committed on behalf of $fname, start another empty $fname
 518                 // transaction, leaving the caller with the same empty transaction state as before.
 519                 if ( $fnameEffective !== $fname ) {
 520                         $this->beginMasterChanges( $fnameEffective );
 521                 }
 522         }
 523
 524         /**
 525          * @param string $dbName DB master name (e.g. "db1052")
 526          * @return float|bool UNIX timestamp when client last touched the DB or false if not recent
 527          * @since 1.28
 528          */
 529         public function getChronologyProtectorTouched( $dbName ) {
 530                 return $this->chronProt->getTouched( $dbName );
 531         }
 532
 533         /**
 534          * Disable the ChronologyProtector for all load balancers
 535          *
 536          * This can be called at the start of special API entry points
 537          *
 538          * @since 1.27
 539          */
 540         public function disableChronologyProtection() {
 541                 $this->chronProt->setEnabled( false );
 542         }
 543
 544         /**
 545          * @return ChronologyProtector
 546          */
 547         protected function newChronologyProtector() {
 548                 $chronProt = new ChronologyProtector(
 549                         $this->memCache,
 550                         [
 551                                 'ip' => isset( $_SERVER[ 'REMOTE_ADDR' ] ) ? $_SERVER[ 'REMOTE_ADDR' ] : '',
 552                                 'agent' => isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : ''
 553                         ],
 554                         isset( $_GET['cpPosTime'] ) ? $_GET['cpPosTime'] : null
 555                 );
 556                 $chronProt->setLogger( $this->replLogger );
 557                 if ( PHP_SAPI === 'cli' ) {
 558                         $chronProt->setEnabled( false );
 559                 }
 560
 561                 return $chronProt;
 562         }
 563
 564         /**
 565          * Get and record all of the staged DB positions into persistent memory storage
 566          *
 567          * @param ChronologyProtector $cp
 568          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 569          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 570          */
 571         protected function shutdownChronologyProtector(
 572                 ChronologyProtector $cp, $workCallback, $mode
 573         ) {
 574                 // Record all the master positions needed
 575                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 576                         $cp->shutdownLB( $lb );
 577                 } );
 578                 // Write them to the persistent stash. Try to do something useful by running $work
 579                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 580                 $unsavedPositions = $cp->shutdown( $workCallback, $mode );
 581                 if ( $unsavedPositions && $workCallback ) {
 582                         // Invoke callback in case it did not cache the result yet
 583                         $workCallback(); // work now to block for less time in waitForAll()
 584                 }
 585                 // If the positions failed to write to the stash, at least wait on local datacenter
 586                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 587                 // the chance that the user will see their own changes immediately afterwards. As long
 588                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 589                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 590                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 591                         if ( isset( $unsavedPositions[$masterName] ) ) {
 592                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 593                         }
 594                 } );
 595         }
 596
 597         /**
 598          * Base parameters to LoadBalancer::__construct()
 599          * @return array
 600          */
 601         final protected function baseLoadBalancerParams() {
 602                 return [
 603                         'localDomain' => $this->domain,
 604                         'readOnlyReason' => $this->readOnlyReason,
 605                         'srvCache' => $this->srvCache,
 606                         'wanCache' => $this->wanCache,
 607                         'trxProfiler' => $this->trxProfiler,
 608                         'queryLogger' => $this->queryLogger,
 609                         'connLogger' => $this->connLogger,
 610                         'replLogger' => $this->replLogger,
 611                         'errorLogger' => $this->errorLogger,
 612                         'hostname' => $this->hostname
 613                 ];
 614         }
 615
 616         /**
 617          * @param ILoadBalancer $lb
 618          */
 619         protected function initLoadBalancer( ILoadBalancer $lb ) {
 620                 if ( $this->trxRoundId !== false ) {
 621                         $lb->beginMasterChanges( $this->trxRoundId ); // set DBO_TRX
 622                 }
 623         }
 624
 625         /**
 626          * Define a new local domain (for testing)
 627          *
 628          * Caller should make sure no local connection are open to the old local domain
 629          *
 630          * @param string $domain
 631          * @since 1.28
 632          */
 633         public function setDomainPrefix( $domain ) {
 634                 $this->domain = $domain;
 635         }
 636
 637         /**
 638          * Close all open database connections on all open load balancers.
 639          * @since 1.28
 640          */
 641         public function closeAll() {
 642                 $this->forEachLBCallMethod( 'closeAll', [] );
 643         }
 644 }