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