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                 // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
 182                 $this->forEachLBCallMethod( 'finalizeMasterChanges' );
 183                 $this->trxRoundId = false;
 184                 // Perform pre-commit checks, aborting on failure
 185                 $this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] );
 186                 // Log the DBs and methods involved in multi-DB transactions
 187                 $this->logIfMultiDbTransaction();
 188                 // Actually perform the commit on all master DB connections and revert DBO_TRX
 189                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 190                 // Run all post-commit callbacks
 191                 /** @var Exception $e */
 192                 $e = null; // first callback exception
 193                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) {
 194                         $ex = $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_COMMIT );
 195                         $e = $e ?: $ex;
 196                 } );
 197                 // Commit any dangling DBO_TRX transactions from callbacks on one DB to another DB
 198                 $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] );
 199                 // Throw any last post-commit callback error
 200                 if ( $e instanceof Exception ) {
 201                         throw $e;
 202                 }
 203         }
 204
 205         public function rollbackMasterChanges( $fname = __METHOD__ ) {
 206                 $this->trxRoundId = false;
 207                 $this->forEachLBCallMethod( 'suppressTransactionEndCallbacks' );
 208                 $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] );
 209                 // Run all post-rollback callbacks
 210                 $this->forEachLB( function ( ILoadBalancer $lb ) {
 211                         $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_ROLLBACK );
 212                 } );
 213         }
 214
 215         /**
 216          * Log query info if multi DB transactions are going to be committed now
 217          */
 218         private function logIfMultiDbTransaction() {
 219                 $callersByDB = [];
 220                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
 221                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 222                         $callers = $lb->pendingMasterChangeCallers();
 223                         if ( $callers ) {
 224                                 $callersByDB[$masterName] = $callers;
 225                         }
 226                 } );
 227
 228                 if ( count( $callersByDB ) >= 2 ) {
 229                         $dbs = implode( ', ', array_keys( $callersByDB ) );
 230                         $msg = "Multi-DB transaction [{$dbs}]:\n";
 231                         foreach ( $callersByDB as $db => $callers ) {
 232                                 $msg .= "$db: " . implode( '; ', $callers ) . "\n";
 233                         }
 234                         $this->queryLogger->info( $msg );
 235                 }
 236         }
 237
 238         public function hasMasterChanges() {
 239                 $ret = false;
 240                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 241                         $ret = $ret || $lb->hasMasterChanges();
 242                 } );
 243
 244                 return $ret;
 245         }
 246
 247         public function laggedReplicaUsed() {
 248                 $ret = false;
 249                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) {
 250                         $ret = $ret || $lb->laggedReplicaUsed();
 251                 } );
 252
 253                 return $ret;
 254         }
 255
 256         public function hasOrMadeRecentMasterChanges( $age = null ) {
 257                 $ret = false;
 258                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
 259                         $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age );
 260                 } );
 261                 return $ret;
 262         }
 263
 264         public function waitForReplication( array $opts = [] ) {
 265                 $opts += [
 266                         'domain' => false,
 267                         'cluster' => false,
 268                         'timeout' => 60,
 269                         'ifWritesSince' => null
 270                 ];
 271
 272                 if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
 273                         $opts['domain'] = $opts['wiki']; // b/c
 274                 }
 275
 276                 // Figure out which clusters need to be checked
 277                 /** @var ILoadBalancer[] $lbs */
 278                 $lbs = [];
 279                 if ( $opts['cluster'] !== false ) {
 280                         $lbs[] = $this->getExternalLB( $opts['cluster'] );
 281                 } elseif ( $opts['domain'] !== false ) {
 282                         $lbs[] = $this->getMainLB( $opts['domain'] );
 283                 } else {
 284                         $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) {
 285                                 $lbs[] = $lb;
 286                         } );
 287                         if ( !$lbs ) {
 288                                 return; // nothing actually used
 289                         }
 290                 }
 291
 292                 // Get all the master positions of applicable DBs right now.
 293                 // This can be faster since waiting on one cluster reduces the
 294                 // time needed to wait on the next clusters.
 295                 $masterPositions = array_fill( 0, count( $lbs ), false );
 296                 foreach ( $lbs as $i => $lb ) {
 297                         if ( $lb->getServerCount() <= 1 ) {
 298                                 // Bug 27975 - Don't try to wait for replica DBs if there are none
 299                                 // Prevents permission error when getting master position
 300                                 continue;
 301                         } elseif ( $opts['ifWritesSince']
 302                                 && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince']
 303                         ) {
 304                                 continue; // no writes since the last wait
 305                         }
 306                         $masterPositions[$i] = $lb->getMasterPos();
 307                 }
 308
 309                 // Run any listener callbacks *after* getting the DB positions. The more
 310                 // time spent in the callbacks, the less time is spent in waitForAll().
 311                 foreach ( $this->replicationWaitCallbacks as $callback ) {
 312                         $callback();
 313                 }
 314
 315                 $failed = [];
 316                 foreach ( $lbs as $i => $lb ) {
 317                         if ( $masterPositions[$i] ) {
 318                                 // The DBMS may not support getMasterPos()
 319                                 if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) {
 320                                         $failed[] = $lb->getServerName( $lb->getWriterIndex() );
 321                                 }
 322                         }
 323                 }
 324
 325                 if ( $failed ) {
 326                         throw new DBReplicationWaitError(
 327                                 "Could not wait for replica DBs to catch up to " .
 328                                 implode( ', ', $failed )
 329                         );
 330                 }
 331         }
 332
 333         public function setWaitForReplicationListener( $name, callable $callback = null ) {
 334                 if ( $callback ) {
 335                         $this->replicationWaitCallbacks[$name] = $callback;
 336                 } else {
 337                         unset( $this->replicationWaitCallbacks[$name] );
 338                 }
 339         }
 340
 341         public function getEmptyTransactionTicket( $fname ) {
 342                 if ( $this->hasMasterChanges() ) {
 343                         $this->queryLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 344                                 ( new RuntimeException() )->getTraceAsString() );
 345
 346                         return null;
 347                 }
 348
 349                 return $this->ticket;
 350         }
 351
 352         public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
 353                 if ( $ticket !== $this->ticket ) {
 354                         $this->perfLogger->error( __METHOD__ . ": $fname does not have outer scope.\n" .
 355                                 ( new RuntimeException() )->getTraceAsString() );
 356
 357                         return;
 358                 }
 359
 360                 // The transaction owner and any caller with the empty transaction ticket can commit
 361                 // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
 362                 if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
 363                         $this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
 364                         $fnameEffective = $this->trxRoundId;
 365                 } else {
 366                         $fnameEffective = $fname;
 367                 }
 368
 369                 $this->commitMasterChanges( $fnameEffective );
 370                 $this->waitForReplication( $opts );
 371                 // If a nested caller committed on behalf of $fname, start another empty $fname
 372                 // transaction, leaving the caller with the same empty transaction state as before.
 373                 if ( $fnameEffective !== $fname ) {
 374                         $this->beginMasterChanges( $fnameEffective );
 375                 }
 376         }
 377
 378         public function getChronologyProtectorTouched( $dbName ) {
 379                 return $this->getChronologyProtector()->getTouched( $dbName );
 380         }
 381
 382         public function disableChronologyProtection() {
 383                 $this->getChronologyProtector()->setEnabled( false );
 384         }
 385
 386         /**
 387          * @return ChronologyProtector
 388          */
 389         protected function getChronologyProtector() {
 390                 if ( $this->chronProt ) {
 391                         return $this->chronProt;
 392                 }
 393
 394                 $this->chronProt = new ChronologyProtector(
 395                         $this->memCache,
 396                         [
 397                                 'ip' => $this->requestInfo['IPAddress'],
 398                                 'agent' => $this->requestInfo['UserAgent'],
 399                         ],
 400                         isset( $_GET['cpPosTime'] ) ? $_GET['cpPosTime'] : null
 401                 );
 402                 $this->chronProt->setLogger( $this->replLogger );
 403
 404                 if ( $this->cliMode ) {
 405                         $this->chronProt->setEnabled( false );
 406                 } elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
 407                         // Request opted out of using position wait logic. This is useful for requests
 408                         // done by the job queue or background ETL that do not have a meaningful session.
 409                         $this->chronProt->setWaitEnabled( false );
 410                 }
 411
 412                 $this->replLogger->debug( __METHOD__ . ': using request info ' .
 413                         json_encode( $this->requestInfo, JSON_PRETTY_PRINT ) );
 414
 415                 return $this->chronProt;
 416         }
 417
 418         /**
 419          * Get and record all of the staged DB positions into persistent memory storage
 420          *
 421          * @param ChronologyProtector $cp
 422          * @param callable|null $workCallback Work to do instead of waiting on syncing positions
 423          * @param string $mode One of (sync, async); whether to wait on remote datacenters
 424          */
 425         protected function shutdownChronologyProtector(
 426                 ChronologyProtector $cp, $workCallback, $mode
 427         ) {
 428                 // Record all the master positions needed
 429                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $cp ) {
 430                         $cp->shutdownLB( $lb );
 431                 } );
 432                 // Write them to the persistent stash. Try to do something useful by running $work
 433                 // while ChronologyProtector waits for the stash write to replicate to all DCs.
 434                 $unsavedPositions = $cp->shutdown( $workCallback, $mode );
 435                 if ( $unsavedPositions && $workCallback ) {
 436                         // Invoke callback in case it did not cache the result yet
 437                         $workCallback(); // work now to block for less time in waitForAll()
 438                 }
 439                 // If the positions failed to write to the stash, at least wait on local datacenter
 440                 // replica DBs to catch up before responding. Even if there are several DCs, this increases
 441                 // the chance that the user will see their own changes immediately afterwards. As long
 442                 // as the sticky DC cookie applies (same domain), this is not even an issue.
 443                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
 444                         $masterName = $lb->getServerName( $lb->getWriterIndex() );
 445                         if ( isset( $unsavedPositions[$masterName] ) ) {
 446                                 $lb->waitForAll( $unsavedPositions[$masterName] );
 447                         }
 448                 } );
 449         }
 450
 451         /**
 452          * Base parameters to LoadBalancer::__construct()
 453          * @return array
 454          */
 455         final protected function baseLoadBalancerParams() {
 456                 return [
 457                         'localDomain' => $this->localDomain,
 458                         'readOnlyReason' => $this->readOnlyReason,
 459                         'srvCache' => $this->srvCache,
 460                         'wanCache' => $this->wanCache,
 461                         'profiler' => $this->profiler,
 462                         'trxProfiler' => $this->trxProfiler,
 463                         'queryLogger' => $this->queryLogger,
 464                         'connLogger' => $this->connLogger,
 465                         'replLogger' => $this->replLogger,
 466                         'errorLogger' => $this->errorLogger,
 467                         'hostname' => $this->hostname,
 468                         'cliMode' => $this->cliMode,
 469                         'agent' => $this->agent
 470                 ];
 471         }
 472
 473         /**
 474          * @param ILoadBalancer $lb
 475          */
 476         protected function initLoadBalancer( ILoadBalancer $lb ) {
 477                 if ( $this->trxRoundId !== false ) {
 478                         $lb->beginMasterChanges( $this->trxRoundId ); // set DBO_TRX
 479                 }
 480         }
 481
 482         public function setDomainPrefix( $prefix ) {
 483                 $this->localDomain = new DatabaseDomain(
 484                         $this->localDomain->getDatabase(),
 485                         null,
 486                         $prefix
 487                 );
 488
 489                 $this->forEachLB( function( ILoadBalancer $lb ) use ( $prefix ) {
 490                         $lb->setDomainPrefix( $prefix );
 491                 } );
 492         }
 493
 494         public function closeAll() {
 495                 $this->forEachLBCallMethod( 'closeAll', [] );
 496         }
 497
 498         public function setAgentName( $agent ) {
 499                 $this->agent = $agent;
 500         }
 501
 502         public function appendPreShutdownTimeAsQuery( $url, $time ) {
 503                 $usedCluster = 0;
 504                 $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
 505                         $usedCluster |= ( $lb->getServerCount() > 1 );
 506                 } );
 507
 508                 if ( !$usedCluster ) {
 509                         return $url; // no master/replica clusters touched
 510                 }
 511
 512                 return strpos( $url, '?' ) === false ? "$url?cpPosTime=$time" : "$url&cpPosTime=$time";
 513         }
 514
 515         public function setRequestInfo( array $info ) {
 516                 $this->requestInfo = $info + $this->requestInfo;
 517         }
 518
 519         function __destruct() {
 520                 $this->destroy();
 521         }
 522 }