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 Psr\Log\NullLogger;
  28 use Wikimedia\ScopedCallback;
  29 use BagOStuff;
  30 use EmptyBagOStuff;
  31 use WANObjectCache;
  32 use Exception;
  33 use RuntimeException;
  34 use LogicException;
  35
  36 /**
  37  * An interface for generating database load balancers
  38  * @ingroup Database
  39  */
  40 abstract class LBFactory implements ILBFactory {
  41         /** @var ChronologyProtector */
  42         private $chronProt;
  43         /** @var object|string Class name or object With profileIn/profileOut methods */
  44         private $profiler;
  45         /** @var TransactionProfiler */
  46         private $trxProfiler;
  47         /** @var LoggerInterface */
  48         private $replLogger;
  49         /** @var LoggerInterface */
  50         private $connLogger;
  51         /** @var LoggerInterface */
  52         private $queryLogger;
  53         /** @var LoggerInterface */
  54         private $perfLogger;
  55         /** @var callable Error logger */
  56         private $errorLogger;
  57         /** @var callable Deprecation logger */
  58         private $deprecationLogger;
  59
  60         /** @var BagOStuff */
  61         protected $srvCache;
  62         /** @var BagOStuff */
  63         protected $memStash;
  64         /** @var WANObjectCache */
  65         protected $wanCache;
  66
  67         /** @var DatabaseDomain Local domain */
  68         protected $localDomain;
  69
  70         /** @var string Local hostname of the app server */
  71         private $hostname;
  72         /** @var array Web request information about the client */
  73         private $requestInfo;
  74         /** @var bool Whether this PHP instance is for a CLI script */
  75         private $cliMode;
  76         /** @var string Agent name for query profiling */
  77         private $agent;
  78         /** @var string Secret string for HMAC hashing */
  79         private $secret;
  80
  81         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  82         private $tableAliases = [];
  83         /** @var string[] Map of (index alias => index) */
  84         private $indexAliases = [];
  85         /** @var callable[] */
  86         private $replicationWaitCallbacks = [];
  87
  88         /** var int An identifier for this class instance */
  89         private $id;
  90         /** @var int|null Ticket used to delegate transaction ownership */
  91         private $ticket;
  92         /** @var string|bool String if a requested DBO_TRX transaction round is active */
  93         private $trxRoundId = false;
  94         /** @var string One of the ROUND_* class constants */
  95         private $trxRoundStage = self::ROUND_CURSORY;
  96
  97         /** @var string|bool Reason all LBs are read-only or false if not */
  98         protected $readOnlyReason = false;
  99
 100         /** @var string|null */
 101         private $defaultGroup = null;
 102
 103         /** @var int|null */
 104         protected $maxLag;
 105
 106         const ROUND_CURSORY = 'cursory';
 107         const ROUND_BEGINNING = 'within-begin';
 108         const ROUND_COMMITTING = 'within-commit';
 109         const ROUND_ROLLING_BACK = 'within-rollback';
 110         const ROUND_COMMIT_CALLBACKS = 'within-commit-callbacks';
 111         const ROUND_ROLLBACK_CALLBACKS = 'within-rollback-callbacks';
 112
 113         private static $loggerFields =
 114                 [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];
 115
 116         public function __construct( array $conf ) {
 117                 $this->localDomain = isset( $conf['localDomain'] )
 118                         ? DatabaseDomain::newFromId( $conf['localDomain'] )
 119                         : DatabaseDomain::newUnspecified();
 120
 121                 $this->maxLag = $conf['maxLag'] ?? null;
 122                 if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
 123                         $this->readOnlyReason = $conf['readOnlyReason'];
 124                 }
 125
 126                 $this->srvCache = $conf['srvCache'] ?? new EmptyBagOStuff();
 127                 $this->memStash = $conf['memStash'] ?? new EmptyBagOStuff();
 128                 $this->wanCache = $conf['wanCache'] ?? WANObjectCache::newEmpty();
 129
 130                 foreach ( self::$loggerFields as $key ) {
 131                         $this->$key = $conf[$key] ?? new NullLogger();
 132                 }
 133                 $this->errorLogger = $conf['errorLogger'] ?? function ( Exception $e ) {
 134                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 135                 };
 136                 $this->deprecationLogger = $conf['deprecationLogger'] ?? function ( $msg ) {
 137                         trigger_error( $msg, E_USER_DEPRECATED );
 138                 };
 139
 140                 $this->profiler = $conf['profiler'] ?? null;
 141                 $this->trxProfiler = $conf['trxProfiler'] ?? new TransactionProfiler();
 142
 143                 $this->requestInfo = [
 144                         'IPAddress' => $_SERVER[ 'REMOTE_ADDR' ] ?? '',
 145                         'UserAgent' => $_SERVER['HTTP_USER_AGENT'] ?? '',
 146                         // Headers application can inject via LBFactory::setRequestInfo()
 147                         'ChronologyProtection' => null,
 148                         'ChronologyClientId' => null, // prior $cpClientId value from LBFactory::shutdown()
 149                         'ChronologyPositionIndex' => null // prior $cpIndex value from LBFactory::shutdown()
 150                 ];
 151
 152                 $this->cliMode = $conf['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 153                 $this->hostname = $conf['hostname'] ?? gethostname();
 154                 $this->agent = $conf['agent'] ?? '';
 155                 $this->defaultGroup = $conf['defaultGroup'] ?? null;
 156                 $this->secret = $conf['secret'] ?? '';
 157
 158                 $this->id = mt_rand();
 159                 $this->ticket = mt_rand();
 160         }
 161
 162         public function destroy() {
 163                 $this->shutdown( self::SHUTDOWN_NO_CHRONPROT );
 164                 $this->forEachLBCallMethod( 'disable' );
 165         }
 166
 167         public function getLocalDomainID() {
 168                 return $this->localDomain->getId();
 169         }
 170
 171         public function resolveDomainID( $domain ) {
 172                 return ( $domain !== false ) ? (string)$domain : $this->getLocalDomainID();
 173         }
 174
 175         public function shutdown(
 176                 $mode = self::SHUTDOWN_CHRONPROT_SYNC,
 177                 callable $workCallback = null,
 178                 &$cpIndex = null,
 179                 &$cpClientId = null
 180         ) {
 181                 $chronProt = $this->getChronologyProtector();
 182                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 183                         $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync', $cpIndex );
 184                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 185                         $this->shutdownChronologyProtector( $chronProt, null, 'async', $cpIndex );
 186                 }
 187
 188                 $cpClientId = $chronProt->getClientId();
 189
 190                 $this->commitMasterChanges( __METHOD__ ); // sanity
 191         }
 192
 193         /**
 194          * @see ILBFactory::newMainLB()
 195          * @param bool $domain
 196          * @return ILoadBalancer
 197          */
 198         abstract public function newMainLB( $domain = false );
 199
 200         /**
 201          * @see ILBFactory::getMainLB()
 202          * @param bool $domain
 203          * @return ILoadBalancer
 204          */
 205         abstract public function getMainLB( $domain = false );
 206
 207         /**
 208          * @see ILBFactory::newExternalLB()
 209          * @param string $cluster
 210          * @return ILoadBalancer
 211          */
 212         abstract public function newExternalLB( $cluster );
 213
 214         /**
 215          * @see ILBFactory::getExternalLB()
 216          * @param string $cluster
 217          * @return ILoadBalancer
 218          */
 219         abstract public function getExternalLB( $cluster );
 220
 221         /**
 222          * Call a method of each tracked load balancer
 223          *
 224          * @param string $methodName
 225          * @param array $args
 226          */
 227         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 228                 $this->forEachLB(
 229                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 230                                 $loadBalancer->$methodName( ...$args );
 231                         },
 232                         [ $methodName, $args ]
 233                 );
 234         }
 235
 236         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 237                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 238                         $this->queryLogger->warning(
 239                                 "$fname: transaction round '{$this->trxRoundId}' still running",
 240                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 241                         );
 242                 }
 243                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 244         }
 245
 246         final public function commitAll( $fname = __METHOD__, array $options = [] ) {
 247                 $this->commitMasterChanges( $fname, $options );
 248                 $this->forEachLBCallMethod( 'flushMasterSnapshots', [ $fname ] );
 249                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 250         }
 251
 252         final public function beginMasterChanges( $fname = __METHOD__ ) {
 253                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 254                 $this->trxRoundStage = self::ROUND_BEGINNING;
 255                 if ( $this->trxRoundId !== false ) {
 256                         throw new DBTransactionError(
 257                                 null,
 258                                 "$fname: transaction round '{$this->trxRoundId}' already started"
 259                         );
 260                 }
 261                 $this->trxRoundId = $fname;
 262                 // Set DBO_TRX flags on all appropriate DBs
 263                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname, $this->id ] );
 264                 $this->trxRoundStage = self::ROUND_CURSORY;
 265         }
 266
 267         final public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 268                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 269                 $this->trxRoundStage = self::ROUND_COMMITTING;
 270                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 271                         throw new DBTransactionError(
 272                                 null,
 273                                 "$fname: transaction round '{$this->trxRoundId}' still running"
 274                         );
 275                 }
 276                 /** @noinspection PhpUnusedLocalVariableInspection */
 277                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 278                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 279                 do {
 280                         $count = 0; // number of callbacks executed this iteration
 281                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$count, $fname ) {
 282                                 $count += $lb->finalizeMasterChanges( $fname, $this->id );
 283                         } );
 284                 } while ( $count > 0 );
 285                 $this->trxRoundId = false;
 286                 // Perform pre-commit checks, aborting on failure
 287                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options, $fname, $this->id ] );
 288                 // Log the DBs and methods involved in multi-DB transactions
 289                 $this->logIfMultiDbTransaction();
 290                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 291                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname, $this->id ] );
 292                 // Run all post-commit callbacks in a separate step
 293                 $this->trxRoundStage = self::ROUND_COMMIT_CALLBACKS;
 294                 $e = $this->executePostTransactionCallbacks();
 295                 $this->trxRoundStage = self::ROUND_CURSORY;
 296                 // Throw any last post-commit callback error
 297                 if ( $e instanceof Exception ) {
 298                         throw $e;
 299                 }
 300         }
 301
 302         final public function rollbackMasterChanges( $fname = __METHOD__ ) {
 303                 $this->trxRoundStage = self::ROUND_ROLLING_BACK;
 304                 $this->trxRoundId = false;
 305                 // Actually perform the rollback on all master DB connections and revert DBO_TRX
 306                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname, $this->id ] );
 307                 // Run all post-commit callbacks in a separate step
 308                 $this->trxRoundStage = self::ROUND_ROLLBACK_CALLBACKS;
 309                 $this->executePostTransactionCallbacks();
 310                 $this->trxRoundStage = self::ROUND_CURSORY;
 311         }
 312
 313         /**
 314          * @return Exception|null
 315          */
 316         private function executePostTransactionCallbacks() {
 317                 $fname = __METHOD__;
 318                 // Run all post-commit callbacks until new ones stop getting added
 319                 $e = null; // first callback exception
 320                 do {
 321                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
 322                                 $ex = $lb->runMasterTransactionIdleCallbacks( $fname, $this->id );
 323                                 $e = $e ?: $ex;
 324                         } );
 325                 } while ( $this->hasMasterChanges() );
 326                 // Run all listener callbacks once
 327                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
 328                         $ex = $lb->runMasterTransactionListenerCallbacks( $fname, $this->id );
 329                         $e = $e ?: $ex;
 330                 } );
 331
 332                 return $e;
 333         }
 334
 335         public function hasTransactionRound() {
 336                 return ( $this->trxRoundId !== false );
 337         }
 338
 339         public function isReadyForRoundOperations() {
 340                 return ( $this->trxRoundStage === self::ROUND_CURSORY );
 341         }
 342
 343         /**
 344          * Log query info if multi DB transactions are going to be committed now
 345          */
 346         private function logIfMultiDbTransaction() {
 347                 $callersByDB = [];
 348                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 349                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 350                         $callers = $lb->pendingMasterChangeCallers();
 351                         if ( $callers ) {
 352                                 $callersByDB[$masterName] = $callers;
 353                         }
 354                 } );
 355
 356                 if ( count( $callersByDB ) >= 2 ) {
 357                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 358                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 359                         foreach ( $callersByDB as $db => $callers ) {
 360                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 361                         }
 362                         $this->queryLogger->info( $msg );
 363                 }
 364         }
 365
 366         public function hasMasterChanges() {
 367                 $ret = false;
 368                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 369                         $ret = $ret || $lb->hasMasterChanges();
 370                 } );
 371
 372                 return $ret;
 373         }
 374
 375         public function laggedReplicaUsed() {
 376                 $ret = false;
 377                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 378                         $ret = $ret || $lb->laggedReplicaUsed();
 379                 } );
 380
 381                 return $ret;
 382         }
 383
 384         public function hasOrMadeRecentMasterChanges( $age = null ) {
 385                 $ret = false;
 386                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 387                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 388                 } );
 389                 return $ret;
 390         }
 391
 392         public function waitForReplication( array $opts = [] ) {
 393                 $opts += [
 394                         'domain' => false,
 395                         'cluster' => false,
 396                         'timeout' => $this->cliMode ? 60 : 1,
 397                         'ifWritesSince' => null
 398                 ];
 399
 400                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 401                         $opts['domain'] = $opts['wiki']; // b/c
 402                 }
 403
 404                 // Figure out which clusters need to be checked
 405                 /** @var ILoadBalancer[] $lbs */
 406                 $lbs = [];
 407                 if ( $opts['cluster'] !== false ) {
 408                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 409                 } elseif ( $opts['domain'] !== false ) {
 410                         $lbs[] = $this->getMainLB( $opts['domain'] );
 411                 } else {
 412                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 413                                 $lbs[] = $lb;
 414                         } );
 415                         if ( !$lbs ) {
 416                                 return true; // nothing actually used
 417                         }
 418                 }
 419
 420                 // Get all the master positions of applicable DBs right now.
 421                 // This can be faster since waiting on one cluster reduces the
 422                 // time needed to wait on the next clusters.
 423                 $masterPositions = array_fill( 0, count( $lbs ), false );
 424                 foreach ( $lbs as $i => $lb ) {
 425                         if (
 426                                 // No writes to wait on getting replicated
 427                                 !$lb->hasMasterConnection() ||
 428                                 // No replication; avoid getMasterPos() permissions errors (T29975)
 429                                 !$lb->hasStreamingReplicaServers() ||
 430                                 // No writes since the last replication wait
 431                                 (
 432                                         $opts['ifWritesSince'] &&
 433                                         $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 434                                 )
 435                         ) {
 436                                 continue; // no need to wait
 437                         }
 438
 439                         $masterPositions[$i] = $lb->getMasterPos();
 440                 }
 441
 442                 // Run any listener callbacks *after* getting the DB positions. The more
 443                 // time spent in the callbacks, the less time is spent in waitForAll().
 444                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 445                         $callback();
 446                 }
 447
 448                 $failed = [];
 449                 foreach ( $lbs as $i => $lb ) {
 450                         if ( $masterPositions[$i] ) {
 451                                 // The RDBMS may not support getMasterPos()
 452                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 453                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 454                                 }
 455                         }
 456                 }
 457
 458                 return !$failed;
 459         }
 460
 461         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 462                 if ( $callback ) {
 463                         $this->replicationWaitCallbacks[$name] = $callback;
 464                 } else {
 465                         unset( $this->replicationWaitCallbacks[$name] );
 466                 }
 467         }
 468
 469         public function getEmptyTransactionTicket( $fname ) {
 470                 if ( $this->hasMasterChanges() ) {
 471                         $this->queryLogger->error(
 472                                 __METHOD__ . ": $fname does not have outer scope",
 473                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 474                         );
 475
 476                         return null;
 477                 }
 478
 479                 return $this->ticket;
 480         }
 481
 482         final public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 483                 if ( $ticket !== $this->ticket ) {
 484                         $this->perfLogger->error(
 485                                 __METHOD__ . ": $fname does not have outer scope",
 486                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 487                         );
 488
 489                         return false;
 490                 }
 491
 492                 // The transaction owner and any caller with the empty transaction ticket can commit
 493                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 494                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 495                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}" );
 496                         $fnameEffective = $this->trxRoundId;
 497                 } else {
 498                         $fnameEffective = $fname;
 499                 }
 500
 501                 $this->commitMasterChanges( $fnameEffective );
 502                 $waitSucceeded = $this->waitForReplication( $opts );
 503                 // If a nested caller committed on behalf of $fname, start another empty $fname
 504                 // transaction, leaving the caller with the same empty transaction state as before.
 505                 if ( $fnameEffective !== $fname ) {
 506                         $this->beginMasterChanges( $fnameEffective );
 507                 }
 508
 509                 return $waitSucceeded;
 510         }
 511
 512         public function getChronologyProtectorTouched( $dbName ) {
 513                 return $this->getChronologyProtector()->getTouched( $dbName );
 514         }
 515
 516         public function disableChronologyProtection() {
 517                 $this->getChronologyProtector()->setEnabled( false );
 518         }
 519
 520         /**
 521          * @return ChronologyProtector
 522          */
 523         protected function getChronologyProtector() {
 524                 if ( $this->chronProt ) {
 525                         return $this->chronProt;
 526                 }
 527
 528                 $this->chronProt = new ChronologyProtector(
 529                         $this->memStash,
 530                         [
 531                                 'ip' => $this->requestInfo['IPAddress'],
 532                                 'agent' => $this->requestInfo['UserAgent'],
 533                                 'clientId' => $this->requestInfo['ChronologyClientId'] ?: null
 534                         ],
 535                         $this->requestInfo['ChronologyPositionIndex'],
 536                         $this->secret
 537                 );
 538                 $this->chronProt->setLogger( $this->replLogger );
 539
 540                 if ( $this->cliMode ) {
 541                         $this->chronProt->setEnabled( false );
 542                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 543                         // Request opted out of using position wait logic. This is useful for requests
 544                         // done by the job queue or background ETL that do not have a meaningful session.
 545                         $this->chronProt->setWaitEnabled( false );
 546                 } elseif ( $this->memStash instanceof EmptyBagOStuff ) {
 547                         // No where to store any DB positions and wait for them to appear
 548                         $this->chronProt->setEnabled( false );
 549                         $this->replLogger->info( 'Cannot use ChronologyProtector with EmptyBagOStuff' );
 550                 }
 551
 552                 $this->replLogger->debug(
 553                         __METHOD__ . ': request info ' .
 554                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT )
 555                 );
 556
 557                 return $this->chronProt;
 558         }
 559
 560         /**
 561          * Get and record all of the staged DB positions into persistent memory storage
 562          *
 563          * @param ChronologyProtector $cp
 564          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 565          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 566          * @param int|null &$cpIndex DB position key write counter; incremented on update
 567          */
 568         protected function shutdownChronologyProtector(
 569                 ChronologyProtector $cp, $workCallback, $mode, &$cpIndex = null
 570         ) {
 571                 // Record all the master positions needed
 572                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 573                         $cp->storeSessionReplicationPosition( $lb );
 574                 } );
 575                 // Write them to the persistent stash. Try to do something useful by running $work
 576                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 577                 $unsavedPositions = $cp->shutdown( $workCallback, $mode, $cpIndex );
 578                 if ( $unsavedPositions && $workCallback ) {
 579                         // Invoke callback in case it did not cache the result yet
 580                         $workCallback(); // work now to block for less time in waitForAll()
 581                 }
 582                 // If the positions failed to write to the stash, at least wait on local datacenter
 583                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 584                 // the chance that the user will see their own changes immediately afterwards. As long
 585                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 586                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 587                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 588                         if ( isset( $unsavedPositions[$masterName] ) ) {
 589                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 590                         }
 591                 } );
 592         }
 593
 594         /**
 595          * Base parameters to ILoadBalancer::__construct()
 596          * @return array
 597          */
 598         final protected function baseLoadBalancerParams() {
 599                 if ( $this->trxRoundStage === self::ROUND_COMMIT_CALLBACKS ) {
 600                         $initStage = ILoadBalancer::STAGE_POSTCOMMIT_CALLBACKS;
 601                 } elseif ( $this->trxRoundStage === self::ROUND_ROLLBACK_CALLBACKS ) {
 602                         $initStage = ILoadBalancer::STAGE_POSTROLLBACK_CALLBACKS;
 603                 } else {
 604                         $initStage = null;
 605                 }
 606
 607                 return [
 608                         'localDomain' => $this->localDomain,
 609                         'readOnlyReason' => $this->readOnlyReason,
 610                         'srvCache' => $this->srvCache,
 611                         'wanCache' => $this->wanCache,
 612                         'profiler' => $this->profiler,
 613                         'trxProfiler' => $this->trxProfiler,
 614                         'queryLogger' => $this->queryLogger,
 615                         'connLogger' => $this->connLogger,
 616                         'replLogger' => $this->replLogger,
 617                         'errorLogger' => $this->errorLogger,
 618                         'deprecationLogger' => $this->deprecationLogger,
 619                         'hostname' => $this->hostname,
 620                         'cliMode' => $this->cliMode,
 621                         'agent' => $this->agent,
 622                         'maxLag' => $this->maxLag,
 623                         'defaultGroup' => $this->defaultGroup,
 624                         'chronologyCallback' => function ( ILoadBalancer $lb ) {
 625                                 // Defer ChronologyProtector construction in case setRequestInfo() ends up
 626                                 // being called later (but before the first connection attempt) (T192611)
 627                                 $this->getChronologyProtector()->applySessionReplicationPosition( $lb );
 628                         },
 629                         'roundStage' => $initStage,
 630                         'ownerId' => $this->id
 631                 ];
 632         }
 633
 634         /**
 635          * @param ILoadBalancer $lb
 636          */
 637         protected function initLoadBalancer( ILoadBalancer $lb ) {
 638                 if ( $this->trxRoundId !== false ) {
 639                         $lb->beginMasterChanges( $this->trxRoundId, $this->id ); // set DBO_TRX
 640                 }
 641
 642                 $lb->setTableAliases( $this->tableAliases );
 643                 $lb->setIndexAliases( $this->indexAliases );
 644         }
 645
 646         public function setTableAliases( array $aliases ) {
 647                 $this->tableAliases = $aliases;
 648         }
 649
 650         public function setIndexAliases( array $aliases ) {
 651                 $this->indexAliases = $aliases;
 652         }
 653
 654         /**
 655          * @param string $prefix
 656          * @deprecated Since 1.33
 657          */
 658         public function setDomainPrefix( $prefix ) {
 659                 $this->setLocalDomainPrefix( $prefix );
 660         }
 661
 662         public function setLocalDomainPrefix( $prefix ) {
 663                 $this->localDomain = new DatabaseDomain(
 664                         $this->localDomain->getDatabase(),
 665                         $this->localDomain->getSchema(),
 666                         $prefix
 667                 );
 668
 669                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $prefix ) {
 670                         $lb->setLocalDomainPrefix( $prefix );
 671                 } );
 672         }
 673
 674         public function redefineLocalDomain( $domain ) {
 675                 $this->closeAll();
 676
 677                 $this->localDomain = DatabaseDomain::newFromId( $domain );
 678
 679                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 680                         $lb->redefineLocalDomain( $this->localDomain );
 681                 } );
 682         }
 683
 684         public function closeAll() {
 685                 $this->forEachLBCallMethod( 'closeAll' );
 686         }
 687
 688         public function setAgentName( $agent ) {
 689                 $this->agent = $agent;
 690         }
 691
 692         public function appendShutdownCPIndexAsQuery( $url, $index ) {
 693                 $usedCluster = 0;
 694                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 695                         $usedCluster |= $lb->hasStreamingReplicaServers();
 696                 } );
 697
 698                 if ( !$usedCluster ) {
 699                         return $url; // no master/replica clusters touched
 700                 }
 701
 702                 return strpos( $url, '?' ) === false ? "$url?cpPosIndex=$index" : "$url&cpPosIndex=$index";
 703         }
 704
 705         public function getChronologyProtectorClientId() {
 706                 return $this->getChronologyProtector()->getClientId();
 707         }
 708
 709         /**
 710          * @param int $index Write index
 711          * @param int $time UNIX timestamp; can be used to detect stale cookies (T190082)
 712          * @param string $clientId Agent ID hash from ILBFactory::shutdown()
 713          * @return string Timestamp-qualified write index of the form "<index>@<timestamp>#<hash>"
 714          * @since 1.32
 715          */
 716         public static function makeCookieValueFromCPIndex( $index, $time, $clientId ) {
 717                 return "$index@$time#$clientId";
 718         }
 719
 720         /**
 721          * @param string $value Possible result of LBFactory::makeCookieValueFromCPIndex()
 722          * @param int $minTimestamp Lowest UNIX timestamp that a non-expired value can have
 723          * @return array (index: int or null, clientId: string or null)
 724          * @since 1.32
 725          */
 726         public static function getCPInfoFromCookieValue( $value, $minTimestamp ) {
 727                 static $placeholder = [ 'index' => null, 'clientId' => null ];
 728
 729                 if ( !preg_match( '/^(\d+)@(\d+)#([0-9a-f]{32})$/', $value, $m ) ) {
 730                         return $placeholder; // invalid
 731                 }
 732
 733                 $index = (int)$m[1];
 734                 if ( $index <= 0 ) {
 735                         return $placeholder; // invalid
 736                 } elseif ( isset( $m[2] ) && $m[2] !== '' && (int)$m[2] < $minTimestamp ) {
 737                         return $placeholder; // expired
 738                 }
 739
 740                 $clientId = ( isset( $m[3] ) && $m[3] !== '' ) ? $m[3] : null;
 741
 742                 return [ 'index' => $index, 'clientId' => $clientId ];
 743         }
 744
 745         public function setRequestInfo( array $info ) {
 746                 if ( $this->chronProt ) {
 747                         throw new LogicException( 'ChronologyProtector already initialized' );
 748                 }
 749
 750                 $this->requestInfo = $info + $this->requestInfo;
 751         }
 752
 753         /**
 754          * @param string $stage
 755          */
 756         private function assertTransactionRoundStage( $stage ) {
 757                 if ( $this->trxRoundStage !== $stage ) {
 758                         throw new DBTransactionError(
 759                                 null,
 760                                 "Transaction round stage must be '$stage' (not '{$this->trxRoundStage}')"
 761                         );
 762                 }
 763         }
 764
 765         function __destruct() {
 766                 $this->destroy();
 767         }
 768 }