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                 /** @noinspection PhpUnusedLocalVariableInspection */
 164                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 165
 166                 $this->forEachLBCallMethod( 'disable' );
 167         }
 168
 169         public function getLocalDomainID() {
 170                 return $this->localDomain->getId();
 171         }
 172
 173         public function resolveDomainID( $domain ) {
 174                 return ( $domain !== false ) ? (string)$domain : $this->getLocalDomainID();
 175         }
 176
 177         public function shutdown(
 178                 $mode = self::SHUTDOWN_CHRONPROT_SYNC,
 179                 callable $workCallback = null,
 180                 &$cpIndex = null,
 181                 &$cpClientId = null
 182         ) {
 183                 /** @noinspection PhpUnusedLocalVariableInspection */
 184                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 185
 186                 $chronProt = $this->getChronologyProtector();
 187                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 188                         $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync', $cpIndex );
 189                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 190                         $this->shutdownChronologyProtector( $chronProt, null, 'async', $cpIndex );
 191                 }
 192
 193                 $cpClientId = $chronProt->getClientId();
 194
 195                 $this->commitMasterChanges( __METHOD__ ); // sanity
 196         }
 197
 198         /**
 199          * @see ILBFactory::newMainLB()
 200          * @param bool $domain
 201          * @return ILoadBalancer
 202          */
 203         abstract public function newMainLB( $domain = false );
 204
 205         /**
 206          * @see ILBFactory::getMainLB()
 207          * @param bool $domain
 208          * @return ILoadBalancer
 209          */
 210         abstract public function getMainLB( $domain = false );
 211
 212         /**
 213          * @see ILBFactory::newExternalLB()
 214          * @param string $cluster
 215          * @return ILoadBalancer
 216          */
 217         abstract public function newExternalLB( $cluster );
 218
 219         /**
 220          * @see ILBFactory::getExternalLB()
 221          * @param string $cluster
 222          * @return ILoadBalancer
 223          */
 224         abstract public function getExternalLB( $cluster );
 225
 226         /**
 227          * Call a method of each tracked load balancer
 228          *
 229          * @param string $methodName
 230          * @param array $args
 231          */
 232         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 233                 $this->forEachLB(
 234                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 235                                 $loadBalancer->$methodName( ...$args );
 236                         },
 237                         [ $methodName, $args ]
 238                 );
 239         }
 240
 241         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 242                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 243                         $this->queryLogger->warning(
 244                                 "$fname: transaction round '{$this->trxRoundId}' still running",
 245                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 246                         );
 247                 }
 248                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 249         }
 250
 251         final public function commitAll( $fname = __METHOD__, array $options = [] ) {
 252                 $this->commitMasterChanges( $fname, $options );
 253                 $this->forEachLBCallMethod( 'flushMasterSnapshots', [ $fname ] );
 254                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 255         }
 256
 257         final public function beginMasterChanges( $fname = __METHOD__ ) {
 258                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 259                 /** @noinspection PhpUnusedLocalVariableInspection */
 260                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 261
 262                 $this->trxRoundStage = self::ROUND_BEGINNING;
 263                 if ( $this->trxRoundId !== false ) {
 264                         throw new DBTransactionError(
 265                                 null,
 266                                 "$fname: transaction round '{$this->trxRoundId}' already started"
 267                         );
 268                 }
 269                 $this->trxRoundId = $fname;
 270                 // Set DBO_TRX flags on all appropriate DBs
 271                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname, $this->id ] );
 272                 $this->trxRoundStage = self::ROUND_CURSORY;
 273         }
 274
 275         final public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 276                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 277                 /** @noinspection PhpUnusedLocalVariableInspection */
 278                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 279
 280                 $this->trxRoundStage = self::ROUND_COMMITTING;
 281                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 282                         throw new DBTransactionError(
 283                                 null,
 284                                 "$fname: transaction round '{$this->trxRoundId}' still running"
 285                         );
 286                 }
 287                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 288                 do {
 289                         $count = 0; // number of callbacks executed this iteration
 290                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$count, $fname ) {
 291                                 $count += $lb->finalizeMasterChanges( $fname, $this->id );
 292                         } );
 293                 } while ( $count > 0 );
 294                 $this->trxRoundId = false;
 295                 // Perform pre-commit checks, aborting on failure
 296                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options, $fname, $this->id ] );
 297                 // Log the DBs and methods involved in multi-DB transactions
 298                 $this->logIfMultiDbTransaction();
 299                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 300                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname, $this->id ] );
 301                 // Run all post-commit callbacks in a separate step
 302                 $this->trxRoundStage = self::ROUND_COMMIT_CALLBACKS;
 303                 $e = $this->executePostTransactionCallbacks();
 304                 $this->trxRoundStage = self::ROUND_CURSORY;
 305                 // Throw any last post-commit callback error
 306                 if ( $e instanceof Exception ) {
 307                         throw $e;
 308                 }
 309         }
 310
 311         final public function rollbackMasterChanges( $fname = __METHOD__ ) {
 312                 /** @noinspection PhpUnusedLocalVariableInspection */
 313                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 314
 315                 $this->trxRoundStage = self::ROUND_ROLLING_BACK;
 316                 $this->trxRoundId = false;
 317                 // Actually perform the rollback on all master DB connections and revert DBO_TRX
 318                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname, $this->id ] );
 319                 // Run all post-commit callbacks in a separate step
 320                 $this->trxRoundStage = self::ROUND_ROLLBACK_CALLBACKS;
 321                 $this->executePostTransactionCallbacks();
 322                 $this->trxRoundStage = self::ROUND_CURSORY;
 323         }
 324
 325         /**
 326          * @return Exception|null
 327          */
 328         private function executePostTransactionCallbacks() {
 329                 $fname = __METHOD__;
 330                 // Run all post-commit callbacks until new ones stop getting added
 331                 $e = null; // first callback exception
 332                 do {
 333                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
 334                                 $ex = $lb->runMasterTransactionIdleCallbacks( $fname, $this->id );
 335                                 $e = $e ?: $ex;
 336                         } );
 337                 } while ( $this->hasMasterChanges() );
 338                 // Run all listener callbacks once
 339                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
 340                         $ex = $lb->runMasterTransactionListenerCallbacks( $fname, $this->id );
 341                         $e = $e ?: $ex;
 342                 } );
 343
 344                 return $e;
 345         }
 346
 347         public function hasTransactionRound() {
 348                 return ( $this->trxRoundId !== false );
 349         }
 350
 351         public function isReadyForRoundOperations() {
 352                 return ( $this->trxRoundStage === self::ROUND_CURSORY );
 353         }
 354
 355         /**
 356          * Log query info if multi DB transactions are going to be committed now
 357          */
 358         private function logIfMultiDbTransaction() {
 359                 $callersByDB = [];
 360                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 361                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 362                         $callers = $lb->pendingMasterChangeCallers();
 363                         if ( $callers ) {
 364                                 $callersByDB[$masterName] = $callers;
 365                         }
 366                 } );
 367
 368                 if ( count( $callersByDB ) >= 2 ) {
 369                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 370                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 371                         foreach ( $callersByDB as $db => $callers ) {
 372                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 373                         }
 374                         $this->queryLogger->info( $msg );
 375                 }
 376         }
 377
 378         public function hasMasterChanges() {
 379                 $ret = false;
 380                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 381                         $ret = $ret || $lb->hasMasterChanges();
 382                 } );
 383
 384                 return $ret;
 385         }
 386
 387         public function laggedReplicaUsed() {
 388                 $ret = false;
 389                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 390                         $ret = $ret || $lb->laggedReplicaUsed();
 391                 } );
 392
 393                 return $ret;
 394         }
 395
 396         public function hasOrMadeRecentMasterChanges( $age = null ) {
 397                 $ret = false;
 398                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 399                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 400                 } );
 401                 return $ret;
 402         }
 403
 404         public function waitForReplication( array $opts = [] ) {
 405                 $opts += [
 406                         'domain' => false,
 407                         'cluster' => false,
 408                         'timeout' => $this->cliMode ? 60 : 1,
 409                         'ifWritesSince' => null
 410                 ];
 411
 412                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 413                         $opts['domain'] = $opts['wiki']; // b/c
 414                 }
 415
 416                 // Figure out which clusters need to be checked
 417                 /** @var ILoadBalancer[] $lbs */
 418                 $lbs = [];
 419                 if ( $opts['cluster'] !== false ) {
 420                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 421                 } elseif ( $opts['domain'] !== false ) {
 422                         $lbs[] = $this->getMainLB( $opts['domain'] );
 423                 } else {
 424                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 425                                 $lbs[] = $lb;
 426                         } );
 427                         if ( !$lbs ) {
 428                                 return true; // nothing actually used
 429                         }
 430                 }
 431
 432                 // Get all the master positions of applicable DBs right now.
 433                 // This can be faster since waiting on one cluster reduces the
 434                 // time needed to wait on the next clusters.
 435                 $masterPositions = array_fill( 0, count( $lbs ), false );
 436                 foreach ( $lbs as $i => $lb ) {
 437                         if (
 438                                 // No writes to wait on getting replicated
 439                                 !$lb->hasMasterConnection() ||
 440                                 // No replication; avoid getMasterPos() permissions errors (T29975)
 441                                 !$lb->hasStreamingReplicaServers() ||
 442                                 // No writes since the last replication wait
 443                                 (
 444                                         $opts['ifWritesSince'] &&
 445                                         $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 446                                 )
 447                         ) {
 448                                 continue; // no need to wait
 449                         }
 450
 451                         $masterPositions[$i] = $lb->getMasterPos();
 452                 }
 453
 454                 // Run any listener callbacks *after* getting the DB positions. The more
 455                 // time spent in the callbacks, the less time is spent in waitForAll().
 456                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 457                         $callback();
 458                 }
 459
 460                 $failed = [];
 461                 foreach ( $lbs as $i => $lb ) {
 462                         if ( $masterPositions[$i] ) {
 463                                 // The RDBMS may not support getMasterPos()
 464                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 465                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 466                                 }
 467                         }
 468                 }
 469
 470                 return !$failed;
 471         }
 472
 473         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 474                 if ( $callback ) {
 475                         $this->replicationWaitCallbacks[$name] = $callback;
 476                 } else {
 477                         unset( $this->replicationWaitCallbacks[$name] );
 478                 }
 479         }
 480
 481         public function getEmptyTransactionTicket( $fname ) {
 482                 if ( $this->hasMasterChanges() ) {
 483                         $this->queryLogger->error(
 484                                 __METHOD__ . ": $fname does not have outer scope",
 485                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 486                         );
 487
 488                         return null;
 489                 }
 490
 491                 return $this->ticket;
 492         }
 493
 494         final public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 495                 if ( $ticket !== $this->ticket ) {
 496                         $this->perfLogger->error(
 497                                 __METHOD__ . ": $fname does not have outer scope",
 498                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 499                         );
 500
 501                         return false;
 502                 }
 503
 504                 // The transaction owner and any caller with the empty transaction ticket can commit
 505                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 506                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 507                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}" );
 508                         $fnameEffective = $this->trxRoundId;
 509                 } else {
 510                         $fnameEffective = $fname;
 511                 }
 512
 513                 $this->commitMasterChanges( $fnameEffective );
 514                 $waitSucceeded = $this->waitForReplication( $opts );
 515                 // If a nested caller committed on behalf of $fname, start another empty $fname
 516                 // transaction, leaving the caller with the same empty transaction state as before.
 517                 if ( $fnameEffective !== $fname ) {
 518                         $this->beginMasterChanges( $fnameEffective );
 519                 }
 520
 521                 return $waitSucceeded;
 522         }
 523
 524         public function getChronologyProtectorTouched( $dbName ) {
 525                 return $this->getChronologyProtector()->getTouched( $dbName );
 526         }
 527
 528         public function disableChronologyProtection() {
 529                 $this->getChronologyProtector()->setEnabled( false );
 530         }
 531
 532         /**
 533          * @return ChronologyProtector
 534          */
 535         protected function getChronologyProtector() {
 536                 if ( $this->chronProt ) {
 537                         return $this->chronProt;
 538                 }
 539
 540                 $this->chronProt = new ChronologyProtector(
 541                         $this->memStash,
 542                         [
 543                                 'ip' => $this->requestInfo['IPAddress'],
 544                                 'agent' => $this->requestInfo['UserAgent'],
 545                                 'clientId' => $this->requestInfo['ChronologyClientId'] ?: null
 546                         ],
 547                         $this->requestInfo['ChronologyPositionIndex'],
 548                         $this->secret
 549                 );
 550                 $this->chronProt->setLogger( $this->replLogger );
 551
 552                 if ( $this->cliMode ) {
 553                         $this->chronProt->setEnabled( false );
 554                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 555                         // Request opted out of using position wait logic. This is useful for requests
 556                         // done by the job queue or background ETL that do not have a meaningful session.
 557                         $this->chronProt->setWaitEnabled( false );
 558                 } elseif ( $this->memStash instanceof EmptyBagOStuff ) {
 559                         // No where to store any DB positions and wait for them to appear
 560                         $this->chronProt->setEnabled( false );
 561                         $this->replLogger->info( 'Cannot use ChronologyProtector with EmptyBagOStuff' );
 562                 }
 563
 564                 $this->replLogger->debug(
 565                         __METHOD__ . ': request info ' .
 566                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT )
 567                 );
 568
 569                 return $this->chronProt;
 570         }
 571
 572         /**
 573          * Get and record all of the staged DB positions into persistent memory storage
 574          *
 575          * @param ChronologyProtector $cp
 576          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 577          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 578          * @param int|null &$cpIndex DB position key write counter; incremented on update
 579          */
 580         protected function shutdownChronologyProtector(
 581                 ChronologyProtector $cp, $workCallback, $mode, &$cpIndex = null
 582         ) {
 583                 // Record all the master positions needed
 584                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 585                         $cp->storeSessionReplicationPosition( $lb );
 586                 } );
 587                 // Write them to the persistent stash. Try to do something useful by running $work
 588                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 589                 $unsavedPositions = $cp->shutdown( $workCallback, $mode, $cpIndex );
 590                 if ( $unsavedPositions && $workCallback ) {
 591                         // Invoke callback in case it did not cache the result yet
 592                         $workCallback(); // work now to block for less time in waitForAll()
 593                 }
 594                 // If the positions failed to write to the stash, at least wait on local datacenter
 595                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 596                 // the chance that the user will see their own changes immediately afterwards. As long
 597                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 598                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 599                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 600                         if ( isset( $unsavedPositions[$masterName] ) ) {
 601                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 602                         }
 603                 } );
 604         }
 605
 606         /**
 607          * Base parameters to ILoadBalancer::__construct()
 608          * @return array
 609          */
 610         final protected function baseLoadBalancerParams() {
 611                 if ( $this->trxRoundStage === self::ROUND_COMMIT_CALLBACKS ) {
 612                         $initStage = ILoadBalancer::STAGE_POSTCOMMIT_CALLBACKS;
 613                 } elseif ( $this->trxRoundStage === self::ROUND_ROLLBACK_CALLBACKS ) {
 614                         $initStage = ILoadBalancer::STAGE_POSTROLLBACK_CALLBACKS;
 615                 } else {
 616                         $initStage = null;
 617                 }
 618
 619                 return [
 620                         'localDomain' => $this->localDomain,
 621                         'readOnlyReason' => $this->readOnlyReason,
 622                         'srvCache' => $this->srvCache,
 623                         'wanCache' => $this->wanCache,
 624                         'profiler' => $this->profiler,
 625                         'trxProfiler' => $this->trxProfiler,
 626                         'queryLogger' => $this->queryLogger,
 627                         'connLogger' => $this->connLogger,
 628                         'replLogger' => $this->replLogger,
 629                         'errorLogger' => $this->errorLogger,
 630                         'deprecationLogger' => $this->deprecationLogger,
 631                         'hostname' => $this->hostname,
 632                         'cliMode' => $this->cliMode,
 633                         'agent' => $this->agent,
 634                         'maxLag' => $this->maxLag,
 635                         'defaultGroup' => $this->defaultGroup,
 636                         'chronologyCallback' => function ( ILoadBalancer $lb ) {
 637                                 // Defer ChronologyProtector construction in case setRequestInfo() ends up
 638                                 // being called later (but before the first connection attempt) (T192611)
 639                                 $this->getChronologyProtector()->applySessionReplicationPosition( $lb );
 640                         },
 641                         'roundStage' => $initStage,
 642                         'ownerId' => $this->id
 643                 ];
 644         }
 645
 646         /**
 647          * @param ILoadBalancer $lb
 648          */
 649         protected function initLoadBalancer( ILoadBalancer $lb ) {
 650                 if ( $this->trxRoundId !== false ) {
 651                         $lb->beginMasterChanges( $this->trxRoundId, $this->id ); // set DBO_TRX
 652                 }
 653
 654                 $lb->setTableAliases( $this->tableAliases );
 655                 $lb->setIndexAliases( $this->indexAliases );
 656         }
 657
 658         public function setTableAliases( array $aliases ) {
 659                 $this->tableAliases = $aliases;
 660         }
 661
 662         public function setIndexAliases( array $aliases ) {
 663                 $this->indexAliases = $aliases;
 664         }
 665
 666         public function setLocalDomainPrefix( $prefix ) {
 667                 $this->localDomain = new DatabaseDomain(
 668                         $this->localDomain->getDatabase(),
 669                         $this->localDomain->getSchema(),
 670                         $prefix
 671                 );
 672
 673                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $prefix ) {
 674                         $lb->setLocalDomainPrefix( $prefix );
 675                 } );
 676         }
 677
 678         public function redefineLocalDomain( $domain ) {
 679                 $this->closeAll();
 680
 681                 $this->localDomain = DatabaseDomain::newFromId( $domain );
 682
 683                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 684                         $lb->redefineLocalDomain( $this->localDomain );
 685                 } );
 686         }
 687
 688         public function closeAll() {
 689                 /** @noinspection PhpUnusedLocalVariableInspection */
 690                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 691
 692                 $this->forEachLBCallMethod( 'closeAll' );
 693         }
 694
 695         public function setAgentName( $agent ) {
 696                 $this->agent = $agent;
 697         }
 698
 699         public function appendShutdownCPIndexAsQuery( $url, $index ) {
 700                 $usedCluster = 0;
 701                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 702                         $usedCluster |= $lb->hasStreamingReplicaServers();
 703                 } );
 704
 705                 if ( !$usedCluster ) {
 706                         return $url; // no master/replica clusters touched
 707                 }
 708
 709                 return strpos( $url, '?' ) === false ? "$url?cpPosIndex=$index" : "$url&cpPosIndex=$index";
 710         }
 711
 712         public function getChronologyProtectorClientId() {
 713                 return $this->getChronologyProtector()->getClientId();
 714         }
 715
 716         /**
 717          * @param int $index Write index
 718          * @param int $time UNIX timestamp; can be used to detect stale cookies (T190082)
 719          * @param string $clientId Agent ID hash from ILBFactory::shutdown()
 720          * @return string Timestamp-qualified write index of the form "<index>@<timestamp>#<hash>"
 721          * @since 1.32
 722          */
 723         public static function makeCookieValueFromCPIndex( $index, $time, $clientId ) {
 724                 return "$index@$time#$clientId";
 725         }
 726
 727         /**
 728          * @param string $value Possible result of LBFactory::makeCookieValueFromCPIndex()
 729          * @param int $minTimestamp Lowest UNIX timestamp that a non-expired value can have
 730          * @return array (index: int or null, clientId: string or null)
 731          * @since 1.32
 732          */
 733         public static function getCPInfoFromCookieValue( $value, $minTimestamp ) {
 734                 static $placeholder = [ 'index' => null, 'clientId' => null ];
 735
 736                 if ( !preg_match( '/^(\d+)@(\d+)#([0-9a-f]{32})$/', $value, $m ) ) {
 737                         return $placeholder; // invalid
 738                 }
 739
 740                 $index = (int)$m[1];
 741                 if ( $index <= 0 ) {
 742                         return $placeholder; // invalid
 743                 } elseif ( isset( $m[2] ) && $m[2] !== '' && (int)$m[2] < $minTimestamp ) {
 744                         return $placeholder; // expired
 745                 }
 746
 747                 $clientId = ( isset( $m[3] ) && $m[3] !== '' ) ? $m[3] : null;
 748
 749                 return [ 'index' => $index, 'clientId' => $clientId ];
 750         }
 751
 752         public function setRequestInfo( array $info ) {
 753                 if ( $this->chronProt ) {
 754                         throw new LogicException( 'ChronologyProtector already initialized' );
 755                 }
 756
 757                 $this->requestInfo = $info + $this->requestInfo;
 758         }
 759
 760         /**
 761          * @param string $stage
 762          */
 763         private function assertTransactionRoundStage( $stage ) {
 764                 if ( $this->trxRoundStage !== $stage ) {
 765                         throw new DBTransactionError(
 766                                 null,
 767                                 "Transaction round stage must be '$stage' (not '{$this->trxRoundStage}')"
 768                         );
 769                 }
 770         }
 771
 772         function __destruct() {
 773                 $this->destroy();
 774         }
 775 }