includes/libs/rdbms/lbfactory/LBFactory.php

   1 <?php
   2 /**
   3  * Generator and manager of database load balancing objects
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23
  24 use Psr\Log\LoggerInterface;
  25
  26 /**
  27  * An interface for generating database load balancers
  28  * @ingroup Database
  29  */
  30 abstract class LBFactory implements ILBFactory {
  31         /** @var ChronologyProtector */
  32         protected $chronProt;
  33         /** @var object|string Class name or object With profileIn/profileOut methods */
  34         protected $profiler;
  35         /** @var TransactionProfiler */
  36         protected $trxProfiler;
  37         /** @var LoggerInterface */
  38         protected $replLogger;
  39         /** @var LoggerInterface */
  40         protected $connLogger;
  41         /** @var LoggerInterface */
  42         protected $queryLogger;
  43         /** @var LoggerInterface */
  44         protected $perfLogger;
  45         /** @var callable Error logger */
  46         protected $errorLogger;
  47         /** @var BagOStuff */
  48         protected $srvCache;
  49         /** @var BagOStuff */
  50         protected $memCache;
  51         /** @var WANObjectCache */
  52         protected $wanCache;
  53
  54         /** @var DatabaseDomain Local domain */
  55         protected $localDomain;
  56         /** @var string Local hostname of the app server */
  57         protected $hostname;
  58         /** @var array Web request information about the client */
  59         protected $requestInfo;
  60
  61         /** @var mixed */
  62         protected $ticket;
  63         /** @var string|bool String if a requested DBO_TRX transaction round is active */
  64         protected $trxRoundId = false;
  65         /** @var string|bool Reason all LBs are read-only or false if not */
  66         protected $readOnlyReason = false;
  67         /** @var callable[] */
  68         protected $replicationWaitCallbacks = [];
  69
  70         /** @var bool Whether this PHP instance is for a CLI script */
  71         protected $cliMode;
  72         /** @var string Agent name for query profiling */
  73         protected $agent;
  74
  75         private static $loggerFields =
  76                 [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];
  77
  78         public function __construct( array $conf ) {
  79                 $this->localDomain = isset( $conf['localDomain'] )
  80                         ? DatabaseDomain::newFromId( $conf['localDomain'] )
  81                         : DatabaseDomain::newUnspecified();
  82
  83                 if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
  84                         $this->readOnlyReason = $conf['readOnlyReason'];
  85                 }
  86
  87                 $this->srvCache = isset( $conf['srvCache'] ) ? $conf['srvCache'] : new EmptyBagOStuff();
  88                 $this->memCache = isset( $conf['memCache'] ) ? $conf['memCache'] : new EmptyBagOStuff();
  89                 $this->wanCache = isset( $conf['wanCache'] )
  90                         ? $conf['wanCache']
  91                         : WANObjectCache::newEmpty();
  92
  93                 foreach ( self::$loggerFields as $key ) {
  94                         $this->$key = isset( $conf[$key] ) ? $conf[$key] : new \Psr\Log\NullLogger();
  95                 }
  96                 $this->errorLogger = isset( $conf['errorLogger'] )
  97                         ? $conf['errorLogger']
  98                         : function ( Exception $e ) {
  99                                 trigger_error( E_WARNING, get_class( $e ) . ': ' . $e->getMessage() );
 100                         };
 101
 102                 $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
 103                 $this->trxProfiler = isset( $conf['trxProfiler'] )
 104                         ? $conf['trxProfiler']
 105                         : new TransactionProfiler();
 106
 107                 $this->requestInfo = [
 108                         'IPAddress' => isset( $_SERVER[ 'REMOTE_ADDR' ] ) ? $_SERVER[ 'REMOTE_ADDR' ] : '',
 109                         'UserAgent' => isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : '',
 110                         'ChronologyProtection' => 'true'
 111                 ];
 112
 113                 $this->cliMode = isset( $params['cliMode'] ) ? $params['cliMode'] : PHP_SAPI === 'cli';
 114                 $this->hostname = isset( $conf['hostname'] ) ? $conf['hostname'] : gethostname();
 115                 $this->agent = isset( $params['agent'] ) ? $params['agent'] : '';
 116
 117                 $this->ticket = mt_rand();
 118         }
 119
 120         public function destroy() {
 121                 $this->shutdown( self::SHUTDOWN_NO_CHRONPROT );
 122                 $this->forEachLBCallMethod( 'disable' );
 123         }
 124
 125         public function shutdown(
 126                 $mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null
 127         ) {
 128                 $chronProt = $this->getChronologyProtector();
 129                 if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) {
 130                         $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync' );
 131                 } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) {
 132                         $this->shutdownChronologyProtector( $chronProt, null, 'async' );
 133                 }
 134
 135                 $this->commitMasterChanges( __METHOD__ ); // sanity
 136         }
 137
 138         /**
 139          * Call a method of each tracked load balancer
 140          *
 141          * @param string $methodName
 142          * @param array $args
 143          */
 144         protected function forEachLBCallMethod( $methodName, array $args = [] ) {
 145                 $this->forEachLB(
 146                         function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
 147                                 call_user_func_array( [ $loadBalancer, $methodName ], $args );
 148                         },
 149                         [ $methodName, $args ]
 150                 );
 151         }
 152
 153         public function flushReplicaSnapshots( $fname = __METHOD__ ) {
 154                 $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] );
 155         }
 156
 157         public function commitAll( $fname = __METHOD__, array $options = [] ) {
 158                 $this->commitMasterChanges( $fname, $options );
 159                 $this->forEachLBCallMethod( 'commitAll', [ $fname ] );
 160         }
 161
 162         public function beginMasterChanges( $fname = __METHOD__ ) {
 163                 if ( $this->trxRoundId !== false ) {
 164                         throw new DBTransactionError(
 165                                 null,
 166                                 "$fname: transaction round '{$this->trxRoundId}' already started."
 167                         );
 168                 }
 169                 $this->trxRoundId = $fname;
 170                 // Set DBO_TRX flags on all appropriate DBs
 171                 $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname ] );
 172         }
 173
 174         public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
 175                 if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
 176                         throw new DBTransactionError(
 177                                 null,
 178                                 "$fname: transaction round '{$this->trxRoundId}' still running."
 179                         );
 180                 }
 181                 /** @noinspection PhpUnusedLocalVariableInspection */
 182                 $scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
 183                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 184                 $this->forEachLBCallMethod( 'finalizeMasterChanges' );
 185                 $this->trxRoundId = false;
 186                 // Perform pre-commit checks, aborting on failure
 187                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] );
 188                 // Log the DBs and methods involved in multi-DB transactions
 189                 $this->logIfMultiDbTransaction();
 190                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 191                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 192                 // Run all post-commit callbacks
 193                 /** @var Exception $e */
 194                 $e = null; // first callback exception
 195                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
 196                         $ex = $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_COMMIT );
 197                         $e = $e ?: $ex;
 198                 } );
 199                 // Commit any dangling DBO_TRX transactions from callbacks on one DB to another DB
 200                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 201                 // Throw any last post-commit callback error
 202                 if ( $e instanceof Exception ) {
 203                         throw $e;
 204                 }
 205         }
 206
 207         public function rollbackMasterChanges( $fname = __METHOD__ ) {
 208                 $this->trxRoundId = false;
 209                 $this->forEachLBCallMethod( 'suppressTransactionEndCallbacks' );
 210                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] );
 211                 // Run all post-rollback callbacks
 212                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 213                         $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_ROLLBACK );
 214                 } );
 215         }
 216
 217         /**
 218          * Log query info if multi DB transactions are going to be committed now
 219          */
 220         private function logIfMultiDbTransaction() {
 221                 $callersByDB = [];
 222                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 223                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 224                         $callers = $lb->pendingMasterChangeCallers();
 225                         if ( $callers ) {
 226                                 $callersByDB[$masterName] = $callers;
 227                         }
 228                 } );
 229
 230                 if ( count( $callersByDB ) >= 2 ) {
 231                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 232                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 233                         foreach ( $callersByDB as $db => $callers ) {
 234                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 235                         }
 236                         $this->queryLogger->info( $msg );
 237                 }
 238         }
 239
 240         public function hasMasterChanges() {
 241                 $ret = false;
 242                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 243                         $ret = $ret || $lb->hasMasterChanges();
 244                 } );
 245
 246                 return $ret;
 247         }
 248
 249         public function laggedReplicaUsed() {
 250                 $ret = false;
 251                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 252                         $ret = $ret || $lb->laggedReplicaUsed();
 253                 } );
 254
 255                 return $ret;
 256         }
 257
 258         public function hasOrMadeRecentMasterChanges( $age = null ) {
 259                 $ret = false;
 260                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 261                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 262                 } );
 263                 return $ret;
 264         }
 265
 266         public function waitForReplication( array $opts = [] ) {
 267                 $opts += [
 268                         'domain' => false,
 269                         'cluster' => false,
 270                         'timeout' => 60,
 271                         'ifWritesSince' => null
 272                 ];
 273
 274                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 275                         $opts['domain'] = $opts['wiki']; // b/c
 276                 }
 277
 278                 // Figure out which clusters need to be checked
 279                 /** @var ILoadBalancer[] $lbs */
 280                 $lbs = [];
 281                 if ( $opts['cluster'] !== false ) {
 282                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 283                 } elseif ( $opts['domain'] !== false ) {
 284                         $lbs[] = $this->getMainLB( $opts['domain'] );
 285                 } else {
 286                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 287                                 $lbs[] = $lb;
 288                         } );
 289                         if ( !$lbs ) {
 290                                 return; // nothing actually used
 291                         }
 292                 }
 293
 294                 // Get all the master positions of applicable DBs right now.
 295                 // This can be faster since waiting on one cluster reduces the
 296                 // time needed to wait on the next clusters.
 297                 $masterPositions = array_fill( 0, count( $lbs ), false );
 298                 foreach ( $lbs as $i => $lb ) {
 299                         if ( $lb->getServerCount() <= 1 ) {
 300                                 // Bug 27975 - Don't try to wait for replica DBs if there are none
 301                                 // Prevents permission error when getting master position
 302                                 continue;
 303                         } elseif ( $opts['ifWritesSince']
 304                                 && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 305                         ) {
 306                                 continue; // no writes since the last wait
 307                         }
 308                         $masterPositions[$i] = $lb->getMasterPos();
 309                 }
 310
 311                 // Run any listener callbacks *after* getting the DB positions. The more
 312                 // time spent in the callbacks, the less time is spent in waitForAll().
 313                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 314                         $callback();
 315                 }
 316
 317                 $failed = [];
 318                 foreach ( $lbs as $i => $lb ) {
 319                         if ( $masterPositions[$i] ) {
 320                                 // The DBMS may not support getMasterPos()
 321                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 322                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 323                                 }
 324                         }
 325                 }
 326
 327                 if ( $failed ) {
 328                         throw new DBReplicationWaitError(
 329                                 "Could not wait for replica DBs to catch up to " .
 330                                 implode( ', ', $failed )
 331                         );
 332                 }
 333         }
 334
 335         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 336                 if ( $callback ) {
 337                         $this->replicationWaitCallbacks[$name] = $callback;
 338                 } else {
 339                         unset( $this->replicationWaitCallbacks[$name] );
 340                 }
 341         }
 342
 343         public function getEmptyTransactionTicket( $fname ) {
 344                 if ( $this->hasMasterChanges() ) {
 345                         $this->queryLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 346                                 ( new RuntimeException() )->getTraceAsString() );
 347
 348                         return null;
 349                 }
 350
 351                 return $this->ticket;
 352         }
 353
 354         public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 355                 if ( $ticket !== $this->ticket ) {
 356                         $this->perfLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 357                                 ( new RuntimeException() )->getTraceAsString() );
 358
 359                         return;
 360                 }
 361
 362                 // The transaction owner and any caller with the empty transaction ticket can commit
 363                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 364                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 365                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
 366                         $fnameEffective = $this->trxRoundId;
 367                 } else {
 368                         $fnameEffective = $fname;
 369                 }
 370
 371                 $this->commitMasterChanges( $fnameEffective );
 372                 $this->waitForReplication( $opts );
 373                 // If a nested caller committed on behalf of $fname, start another empty $fname
 374                 // transaction, leaving the caller with the same empty transaction state as before.
 375                 if ( $fnameEffective !== $fname ) {
 376                         $this->beginMasterChanges( $fnameEffective );
 377                 }
 378         }
 379
 380         public function getChronologyProtectorTouched( $dbName ) {
 381                 return $this->getChronologyProtector()->getTouched( $dbName );
 382         }
 383
 384         public function disableChronologyProtection() {
 385                 $this->getChronologyProtector()->setEnabled( false );
 386         }
 387
 388         /**
 389          * @return ChronologyProtector
 390          */
 391         protected function getChronologyProtector() {
 392                 if ( $this->chronProt ) {
 393                         return $this->chronProt;
 394                 }
 395
 396                 $this->chronProt = new ChronologyProtector(
 397                         $this->memCache,
 398                         [
 399                                 'ip' => $this->requestInfo['IPAddress'],
 400                                 'agent' => $this->requestInfo['UserAgent'],
 401                         ],
 402                         isset( $_GET['cpPosTime'] ) ? $_GET['cpPosTime'] : null
 403                 );
 404                 $this->chronProt->setLogger( $this->replLogger );
 405
 406                 if ( $this->cliMode ) {
 407                         $this->chronProt->setEnabled( false );
 408                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 409                         // Request opted out of using position wait logic. This is useful for requests
 410                         // done by the job queue or background ETL that do not have a meaningful session.
 411                         $this->chronProt->setWaitEnabled( false );
 412                 }
 413
 414                 $this->replLogger->debug( __METHOD__ . ': using request info ' .
 415                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT ) );
 416
 417                 return $this->chronProt;
 418         }
 419
 420         /**
 421          * Get and record all of the staged DB positions into persistent memory storage
 422          *
 423          * @param ChronologyProtector $cp
 424          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 425          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 426          */
 427         protected function shutdownChronologyProtector(
 428                 ChronologyProtector $cp, $workCallback, $mode
 429         ) {
 430                 // Record all the master positions needed
 431                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 432                         $cp->shutdownLB( $lb );
 433                 } );
 434                 // Write them to the persistent stash. Try to do something useful by running $work
 435                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 436                 $unsavedPositions = $cp->shutdown( $workCallback, $mode );
 437                 if ( $unsavedPositions && $workCallback ) {
 438                         // Invoke callback in case it did not cache the result yet
 439                         $workCallback(); // work now to block for less time in waitForAll()
 440                 }
 441                 // If the positions failed to write to the stash, at least wait on local datacenter
 442                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 443                 // the chance that the user will see their own changes immediately afterwards. As long
 444                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 445                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 446                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 447                         if ( isset( $unsavedPositions[$masterName] ) ) {
 448                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 449                         }
 450                 } );
 451         }
 452
 453         /**
 454          * Base parameters to LoadBalancer::__construct()
 455          * @return array
 456          */
 457         final protected function baseLoadBalancerParams() {
 458                 return [
 459                         'localDomain' => $this->localDomain,
 460                         'readOnlyReason' => $this->readOnlyReason,
 461                         'srvCache' => $this->srvCache,
 462                         'wanCache' => $this->wanCache,
 463                         'profiler' => $this->profiler,
 464                         'trxProfiler' => $this->trxProfiler,
 465                         'queryLogger' => $this->queryLogger,
 466                         'connLogger' => $this->connLogger,
 467                         'replLogger' => $this->replLogger,
 468                         'errorLogger' => $this->errorLogger,
 469                         'hostname' => $this->hostname,
 470                         'cliMode' => $this->cliMode,
 471                         'agent' => $this->agent
 472                 ];
 473         }
 474
 475         /**
 476          * @param ILoadBalancer $lb
 477          */
 478         protected function initLoadBalancer( ILoadBalancer $lb ) {
 479                 if ( $this->trxRoundId !== false ) {
 480                         $lb->beginMasterChanges( $this->trxRoundId ); // set DBO_TRX
 481                 }
 482         }
 483
 484         public function setDomainPrefix( $prefix ) {
 485                 $this->localDomain = new DatabaseDomain(
 486                         $this->localDomain->getDatabase(),
 487                         null,
 488                         $prefix
 489                 );
 490
 491                 $this->forEachLB( function( ILoadBalancer $lb ) use ( $prefix ) {
 492                         $lb->setDomainPrefix( $prefix );
 493                 } );
 494         }
 495
 496         public function closeAll() {
 497                 $this->forEachLBCallMethod( 'closeAll', [] );
 498         }
 499
 500         public function setAgentName( $agent ) {
 501                 $this->agent = $agent;
 502         }
 503
 504         public function appendPreShutdownTimeAsQuery( $url, $time ) {
 505                 $usedCluster = 0;
 506                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 507                         $usedCluster |= ( $lb->getServerCount() > 1 );
 508                 } );
 509
 510                 if ( !$usedCluster ) {
 511                         return $url; // no master/replica clusters touched
 512                 }
 513
 514                 return strpos( $url, '?' ) === false ? "$url?cpPosTime=$time" : "$url&cpPosTime=$time";
 515         }
 516
 517         public function setRequestInfo( array $info ) {
 518                 $this->requestInfo = $info + $this->requestInfo;
 519         }
 520
 521         /**
 522          * Make PHP ignore user aborts/disconnects until the returned
 523          * value leaves scope. This returns null and does nothing in CLI mode.
 524          *
 525          * @return ScopedCallback|null
 526          */
 527         final protected function getScopedPHPBehaviorForCommit() {
 528                 if ( PHP_SAPI != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
 529                         $old = ignore_user_abort( true ); // avoid half-finished operations
 530                         return new ScopedCallback( function () use ( $old ) {
 531                                 ignore_user_abort( $old );
 532                         } );
 533                 }
 534
 535                 return null;
 536         }
 537
 538         function __destruct() {
 539                 $this->destroy();
 540         }
 541 }