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                 static $nextId, $nextTicket;
 159                 $this->id = $nextId = ( is_int( $nextId ) ? $nextId++ : mt_rand() );
 160                 $this->ticket = $nextTicket = ( is_int( $nextTicket ) ? $nextTicket++ : mt_rand() );
 161         }
 162
 163         public function destroy() {
 164                 /** @noinspection PhpUnusedLocalVariableInspection */
 165                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 166
 167                 $this->forEachLBCallMethod( 'disable', [ __METHOD__, $this->id ] );
 168         }
 169
 170         public function getLocalDomainID() {
 171                 return $this->localDomain->getId();
 172         }
 173
 174         public function resolveDomainID( $domain ) {
 175                 return ( $domain !== false ) ? (string)$domain : $this->getLocalDomainID();
 176         }
 177
 178         public function shutdown(
 179                 $mode = self::SHUTDOWN_CHRONPROT_SYNC,
 180                 callable $workCallback = null,
 181                 &$cpIndex = null,
 182                 &$cpClientId = null
 183         ) {
 184                 /** @noinspection PhpUnusedLocalVariableInspection */
 185                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 186
 187                 $chronProt = $this->getChronologyProtector();
 188                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 189                         $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync', $cpIndex );
 190                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 191                         $this->shutdownChronologyProtector( $chronProt, null, 'async', $cpIndex );
 192                 }
 193
 194                 $cpClientId = $chronProt->getClientId();
 195
 196                 $this->commitMasterChanges( __METHOD__ ); // sanity
 197         }
 198
 199         /**
 200          * Call a method of each tracked load balancer
 201          *
 202          * @param string $methodName
 203          * @param array $args
 204          */
 205         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 206                 $this->forEachLB(
 207                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 208                                 $loadBalancer->$methodName( ...$args );
 209                         },
 210                         [ $methodName, $args ]
 211                 );
 212         }
 213
 214         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 215                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 216                         $this->queryLogger->warning(
 217                                 "$fname: transaction round '{$this->trxRoundId}' still running",
 218                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 219                         );
 220                 }
 221                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname, $this->id ] );
 222         }
 223
 224         final public function commitAll( $fname = __METHOD__, array $options = [] ) {
 225                 $this->commitMasterChanges( $fname, $options );
 226                 $this->forEachLBCallMethod( 'flushMasterSnapshots', [ $fname, $this->id ] );
 227                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname, $this->id ] );
 228         }
 229
 230         final public function beginMasterChanges( $fname = __METHOD__ ) {
 231                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 232                 /** @noinspection PhpUnusedLocalVariableInspection */
 233                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 234
 235                 $this->trxRoundStage = self::ROUND_BEGINNING;
 236                 if ( $this->trxRoundId !== false ) {
 237                         throw new DBTransactionError(
 238                                 null,
 239                                 "$fname: transaction round '{$this->trxRoundId}' already started"
 240                         );
 241                 }
 242                 $this->trxRoundId = $fname;
 243                 // Set DBO_TRX flags on all appropriate DBs
 244                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname, $this->id ] );
 245                 $this->trxRoundStage = self::ROUND_CURSORY;
 246         }
 247
 248         final public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 249                 $this->assertTransactionRoundStage( self::ROUND_CURSORY );
 250                 /** @noinspection PhpUnusedLocalVariableInspection */
 251                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 252
 253                 $this->trxRoundStage = self::ROUND_COMMITTING;
 254                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 255                         throw new DBTransactionError(
 256                                 null,
 257                                 "$fname: transaction round '{$this->trxRoundId}' still running"
 258                         );
 259                 }
 260                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 261                 do {
 262                         $count = 0; // number of callbacks executed this iteration
 263                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$count, $fname ) {
 264                                 $count += $lb->finalizeMasterChanges( $fname, $this->id );
 265                         } );
 266                 } while ( $count > 0 );
 267                 $this->trxRoundId = false;
 268                 // Perform pre-commit checks, aborting on failure
 269                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options, $fname, $this->id ] );
 270                 // Log the DBs and methods involved in multi-DB transactions
 271                 $this->logIfMultiDbTransaction();
 272                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 273                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname, $this->id ] );
 274                 // Run all post-commit callbacks in a separate step
 275                 $this->trxRoundStage = self::ROUND_COMMIT_CALLBACKS;
 276                 $e = $this->executePostTransactionCallbacks();
 277                 $this->trxRoundStage = self::ROUND_CURSORY;
 278                 // Throw any last post-commit callback error
 279                 if ( $e instanceof Exception ) {
 280                         throw $e;
 281                 }
 282         }
 283
 284         final public function rollbackMasterChanges( $fname = __METHOD__ ) {
 285                 /** @noinspection PhpUnusedLocalVariableInspection */
 286                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 287
 288                 $this->trxRoundStage = self::ROUND_ROLLING_BACK;
 289                 $this->trxRoundId = false;
 290                 // Actually perform the rollback on all master DB connections and revert DBO_TRX
 291                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname, $this->id ] );
 292                 // Run all post-commit callbacks in a separate step
 293                 $this->trxRoundStage = self::ROUND_ROLLBACK_CALLBACKS;
 294                 $this->executePostTransactionCallbacks();
 295                 $this->trxRoundStage = self::ROUND_CURSORY;
 296         }
 297
 298         /**
 299          * @return Exception|null
 300          */
 301         private function executePostTransactionCallbacks() {
 302                 $fname = __METHOD__;
 303                 // Run all post-commit callbacks until new ones stop getting added
 304                 $e = null; // first callback exception
 305                 do {
 306                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
 307                                 $ex = $lb->runMasterTransactionIdleCallbacks( $fname, $this->id );
 308                                 $e = $e ?: $ex;
 309                         } );
 310                 } while ( $this->hasMasterChanges() );
 311                 // Run all listener callbacks once
 312                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
 313                         $ex = $lb->runMasterTransactionListenerCallbacks( $fname, $this->id );
 314                         $e = $e ?: $ex;
 315                 } );
 316
 317                 return $e;
 318         }
 319
 320         public function hasTransactionRound() {
 321                 return ( $this->trxRoundId !== false );
 322         }
 323
 324         public function isReadyForRoundOperations() {
 325                 return ( $this->trxRoundStage === self::ROUND_CURSORY );
 326         }
 327
 328         /**
 329          * Log query info if multi DB transactions are going to be committed now
 330          */
 331         private function logIfMultiDbTransaction() {
 332                 $callersByDB = [];
 333                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 334                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 335                         $callers = $lb->pendingMasterChangeCallers();
 336                         if ( $callers ) {
 337                                 $callersByDB[$masterName] = $callers;
 338                         }
 339                 } );
 340
 341                 if ( count( $callersByDB ) >= 2 ) {
 342                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 343                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 344                         foreach ( $callersByDB as $db => $callers ) {
 345                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 346                         }
 347                         $this->queryLogger->info( $msg );
 348                 }
 349         }
 350
 351         public function hasMasterChanges() {
 352                 $ret = false;
 353                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 354                         $ret = $ret || $lb->hasMasterChanges();
 355                 } );
 356
 357                 return $ret;
 358         }
 359
 360         public function laggedReplicaUsed() {
 361                 $ret = false;
 362                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 363                         $ret = $ret || $lb->laggedReplicaUsed();
 364                 } );
 365
 366                 return $ret;
 367         }
 368
 369         public function hasOrMadeRecentMasterChanges( $age = null ) {
 370                 $ret = false;
 371                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 372                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 373                 } );
 374                 return $ret;
 375         }
 376
 377         public function waitForReplication( array $opts = [] ) {
 378                 $opts += [
 379                         'domain' => false,
 380                         'cluster' => false,
 381                         'timeout' => $this->cliMode ? 60 : 1,
 382                         'ifWritesSince' => null
 383                 ];
 384
 385                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 386                         $opts['domain'] = $opts['wiki']; // b/c
 387                 }
 388
 389                 // Figure out which clusters need to be checked
 390                 /** @var ILoadBalancer[] $lbs */
 391                 $lbs = [];
 392                 if ( $opts['cluster'] !== false ) {
 393                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 394                 } elseif ( $opts['domain'] !== false ) {
 395                         $lbs[] = $this->getMainLB( $opts['domain'] );
 396                 } else {
 397                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 398                                 $lbs[] = $lb;
 399                         } );
 400                         if ( !$lbs ) {
 401                                 return true; // nothing actually used
 402                         }
 403                 }
 404
 405                 // Get all the master positions of applicable DBs right now.
 406                 // This can be faster since waiting on one cluster reduces the
 407                 // time needed to wait on the next clusters.
 408                 $masterPositions = array_fill( 0, count( $lbs ), false );
 409                 foreach ( $lbs as $i => $lb ) {
 410                         if (
 411                                 // No writes to wait on getting replicated
 412                                 !$lb->hasMasterConnection() ||
 413                                 // No replication; avoid getMasterPos() permissions errors (T29975)
 414                                 !$lb->hasStreamingReplicaServers() ||
 415                                 // No writes since the last replication wait
 416                                 (
 417                                         $opts['ifWritesSince'] &&
 418                                         $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 419                                 )
 420                         ) {
 421                                 continue; // no need to wait
 422                         }
 423
 424                         $masterPositions[$i] = $lb->getMasterPos();
 425                 }
 426
 427                 // Run any listener callbacks *after* getting the DB positions. The more
 428                 // time spent in the callbacks, the less time is spent in waitForAll().
 429                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 430                         $callback();
 431                 }
 432
 433                 $failed = [];
 434                 foreach ( $lbs as $i => $lb ) {
 435                         if ( $masterPositions[$i] ) {
 436                                 // The RDBMS may not support getMasterPos()
 437                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 438                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 439                                 }
 440                         }
 441                 }
 442
 443                 return !$failed;
 444         }
 445
 446         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 447                 if ( $callback ) {
 448                         $this->replicationWaitCallbacks[$name] = $callback;
 449                 } else {
 450                         unset( $this->replicationWaitCallbacks[$name] );
 451                 }
 452         }
 453
 454         public function getEmptyTransactionTicket( $fname ) {
 455                 if ( $this->hasMasterChanges() ) {
 456                         $this->queryLogger->error(
 457                                 __METHOD__ . ": $fname does not have outer scope",
 458                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 459                         );
 460
 461                         return null;
 462                 }
 463
 464                 return $this->ticket;
 465         }
 466
 467         final public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 468                 if ( $ticket !== $this->ticket ) {
 469                         $this->perfLogger->error(
 470                                 __METHOD__ . ": $fname does not have outer scope",
 471                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 472                         );
 473
 474                         return false;
 475                 }
 476
 477                 // The transaction owner and any caller with the empty transaction ticket can commit
 478                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 479                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 480                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}" );
 481                         $fnameEffective = $this->trxRoundId;
 482                 } else {
 483                         $fnameEffective = $fname;
 484                 }
 485
 486                 $this->commitMasterChanges( $fnameEffective );
 487                 $waitSucceeded = $this->waitForReplication( $opts );
 488                 // If a nested caller committed on behalf of $fname, start another empty $fname
 489                 // transaction, leaving the caller with the same empty transaction state as before.
 490                 if ( $fnameEffective !== $fname ) {
 491                         $this->beginMasterChanges( $fnameEffective );
 492                 }
 493
 494                 return $waitSucceeded;
 495         }
 496
 497         public function getChronologyProtectorTouched( $dbName ) {
 498                 return $this->getChronologyProtector()->getTouched( $dbName );
 499         }
 500
 501         public function disableChronologyProtection() {
 502                 $this->getChronologyProtector()->setEnabled( false );
 503         }
 504
 505         /**
 506          * @return ChronologyProtector
 507          */
 508         protected function getChronologyProtector() {
 509                 if ( $this->chronProt ) {
 510                         return $this->chronProt;
 511                 }
 512
 513                 $this->chronProt = new ChronologyProtector(
 514                         $this->memStash,
 515                         [
 516                                 'ip' => $this->requestInfo['IPAddress'],
 517                                 'agent' => $this->requestInfo['UserAgent'],
 518                                 'clientId' => $this->requestInfo['ChronologyClientId'] ?: null
 519                         ],
 520                         $this->requestInfo['ChronologyPositionIndex'],
 521                         $this->secret
 522                 );
 523                 $this->chronProt->setLogger( $this->replLogger );
 524
 525                 if ( $this->cliMode ) {
 526                         $this->chronProt->setEnabled( false );
 527                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 528                         // Request opted out of using position wait logic. This is useful for requests
 529                         // done by the job queue or background ETL that do not have a meaningful session.
 530                         $this->chronProt->setWaitEnabled( false );
 531                 } elseif ( $this->memStash instanceof EmptyBagOStuff ) {
 532                         // No where to store any DB positions and wait for them to appear
 533                         $this->chronProt->setEnabled( false );
 534                         $this->replLogger->info( 'Cannot use ChronologyProtector with EmptyBagOStuff' );
 535                 }
 536
 537                 $this->replLogger->debug(
 538                         __METHOD__ . ': request info ' .
 539                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT )
 540                 );
 541
 542                 return $this->chronProt;
 543         }
 544
 545         /**
 546          * Get and record all of the staged DB positions into persistent memory storage
 547          *
 548          * @param ChronologyProtector $cp
 549          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 550          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 551          * @param int|null &$cpIndex DB position key write counter; incremented on update
 552          */
 553         protected function shutdownChronologyProtector(
 554                 ChronologyProtector $cp, $workCallback, $mode, &$cpIndex = null
 555         ) {
 556                 // Record all the master positions needed
 557                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 558                         $cp->storeSessionReplicationPosition( $lb );
 559                 } );
 560                 // Write them to the persistent stash. Try to do something useful by running $work
 561                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 562                 $unsavedPositions = $cp->shutdown( $workCallback, $mode, $cpIndex );
 563                 if ( $unsavedPositions && $workCallback ) {
 564                         // Invoke callback in case it did not cache the result yet
 565                         $workCallback(); // work now to block for less time in waitForAll()
 566                 }
 567                 // If the positions failed to write to the stash, at least wait on local datacenter
 568                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 569                 // the chance that the user will see their own changes immediately afterwards. As long
 570                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 571                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 572                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 573                         if ( isset( $unsavedPositions[$masterName] ) ) {
 574                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 575                         }
 576                 } );
 577         }
 578
 579         /**
 580          * Get parameters to ILoadBalancer::__construct()
 581          *
 582          * @param int|null $owner Use getOwnershipId() if this is for getMainLB()/getExternalLB()
 583          * @return array
 584          */
 585         final protected function baseLoadBalancerParams( $owner ) {
 586                 if ( $this->trxRoundStage === self::ROUND_COMMIT_CALLBACKS ) {
 587                         $initStage = ILoadBalancer::STAGE_POSTCOMMIT_CALLBACKS;
 588                 } elseif ( $this->trxRoundStage === self::ROUND_ROLLBACK_CALLBACKS ) {
 589                         $initStage = ILoadBalancer::STAGE_POSTROLLBACK_CALLBACKS;
 590                 } else {
 591                         $initStage = null;
 592                 }
 593
 594                 return [
 595                         'localDomain' => $this->localDomain,
 596                         'readOnlyReason' => $this->readOnlyReason,
 597                         'srvCache' => $this->srvCache,
 598                         'wanCache' => $this->wanCache,
 599                         'profiler' => $this->profiler,
 600                         'trxProfiler' => $this->trxProfiler,
 601                         'queryLogger' => $this->queryLogger,
 602                         'connLogger' => $this->connLogger,
 603                         'replLogger' => $this->replLogger,
 604                         'errorLogger' => $this->errorLogger,
 605                         'deprecationLogger' => $this->deprecationLogger,
 606                         'hostname' => $this->hostname,
 607                         'cliMode' => $this->cliMode,
 608                         'agent' => $this->agent,
 609                         'maxLag' => $this->maxLag,
 610                         'defaultGroup' => $this->defaultGroup,
 611                         'chronologyCallback' => function ( ILoadBalancer $lb ) {
 612                                 // Defer ChronologyProtector construction in case setRequestInfo() ends up
 613                                 // being called later (but before the first connection attempt) (T192611)
 614                                 $this->getChronologyProtector()->applySessionReplicationPosition( $lb );
 615                         },
 616                         'roundStage' => $initStage,
 617                         'ownerId' => $owner
 618                 ];
 619         }
 620
 621         /**
 622          * @param ILoadBalancer $lb
 623          */
 624         protected function initLoadBalancer( ILoadBalancer $lb ) {
 625                 if ( $this->trxRoundId !== false ) {
 626                         $lb->beginMasterChanges( $this->trxRoundId, $this->id ); // set DBO_TRX
 627                 }
 628
 629                 $lb->setTableAliases( $this->tableAliases );
 630                 $lb->setIndexAliases( $this->indexAliases );
 631         }
 632
 633         public function setTableAliases( array $aliases ) {
 634                 $this->tableAliases = $aliases;
 635         }
 636
 637         public function setIndexAliases( array $aliases ) {
 638                 $this->indexAliases = $aliases;
 639         }
 640
 641         public function setLocalDomainPrefix( $prefix ) {
 642                 $this->localDomain = new DatabaseDomain(
 643                         $this->localDomain->getDatabase(),
 644                         $this->localDomain->getSchema(),
 645                         $prefix
 646                 );
 647
 648                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $prefix ) {
 649                         $lb->setLocalDomainPrefix( $prefix );
 650                 } );
 651         }
 652
 653         public function redefineLocalDomain( $domain ) {
 654                 $this->closeAll();
 655
 656                 $this->localDomain = DatabaseDomain::newFromId( $domain );
 657
 658                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 659                         $lb->redefineLocalDomain( $this->localDomain );
 660                 } );
 661         }
 662
 663         public function closeAll() {
 664                 /** @noinspection PhpUnusedLocalVariableInspection */
 665                 $scope = ScopedCallback::newScopedIgnoreUserAbort();
 666
 667                 $this->forEachLBCallMethod( 'closeAll', [ __METHOD__, $this->id ] );
 668         }
 669
 670         public function setAgentName( $agent ) {
 671                 $this->agent = $agent;
 672         }
 673
 674         public function appendShutdownCPIndexAsQuery( $url, $index ) {
 675                 $usedCluster = 0;
 676                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 677                         $usedCluster |= $lb->hasStreamingReplicaServers();
 678                 } );
 679
 680                 if ( !$usedCluster ) {
 681                         return $url; // no master/replica clusters touched
 682                 }
 683
 684                 return strpos( $url, '?' ) === false ? "$url?cpPosIndex=$index" : "$url&cpPosIndex=$index";
 685         }
 686
 687         public function getChronologyProtectorClientId() {
 688                 return $this->getChronologyProtector()->getClientId();
 689         }
 690
 691         /**
 692          * @param int $index Write index
 693          * @param int $time UNIX timestamp; can be used to detect stale cookies (T190082)
 694          * @param string $clientId Agent ID hash from ILBFactory::shutdown()
 695          * @return string Timestamp-qualified write index of the form "<index>@<timestamp>#<hash>"
 696          * @since 1.32
 697          */
 698         public static function makeCookieValueFromCPIndex( $index, $time, $clientId ) {
 699                 return "$index@$time#$clientId";
 700         }
 701
 702         /**
 703          * @param string $value Possible result of LBFactory::makeCookieValueFromCPIndex()
 704          * @param int $minTimestamp Lowest UNIX timestamp that a non-expired value can have
 705          * @return array (index: int or null, clientId: string or null)
 706          * @since 1.32
 707          */
 708         public static function getCPInfoFromCookieValue( $value, $minTimestamp ) {
 709                 static $placeholder = [ 'index' => null, 'clientId' => null ];
 710
 711                 if ( !preg_match( '/^(\d+)@(\d+)#([0-9a-f]{32})$/', $value, $m ) ) {
 712                         return $placeholder; // invalid
 713                 }
 714
 715                 $index = (int)$m[1];
 716                 if ( $index <= 0 ) {
 717                         return $placeholder; // invalid
 718                 } elseif ( isset( $m[2] ) && $m[2] !== '' && (int)$m[2] < $minTimestamp ) {
 719                         return $placeholder; // expired
 720                 }
 721
 722                 $clientId = ( isset( $m[3] ) && $m[3] !== '' ) ? $m[3] : null;
 723
 724                 return [ 'index' => $index, 'clientId' => $clientId ];
 725         }
 726
 727         public function setRequestInfo( array $info ) {
 728                 if ( $this->chronProt ) {
 729                         throw new LogicException( 'ChronologyProtector already initialized' );
 730                 }
 731
 732                 $this->requestInfo = $info + $this->requestInfo;
 733         }
 734
 735         /**
 736          * @return int Internal instance ID used to assert ownership of ILoadBalancer instances
 737          * @since 1.34
 738          */
 739         final protected function getOwnershipId() {
 740                 return $this->id;
 741         }
 742
 743         /**
 744          * @param string $stage
 745          */
 746         private function assertTransactionRoundStage( $stage ) {
 747                 if ( $this->trxRoundStage !== $stage ) {
 748                         throw new DBTransactionError(
 749                                 null,
 750                                 "Transaction round stage must be '$stage' (not '{$this->trxRoundStage}')"
 751                         );
 752                 }
 753         }
 754
 755         function __destruct() {
 756                 $this->destroy();
 757         }
 758 }