includes/jobqueue/JobQueueDB.php

   1 <?php
   2 /**
   3  * Database-backed job queue code.
   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  */
  22 use Wikimedia\Rdbms\IDatabase;
  23 use Wikimedia\Rdbms\Database;
  24 use Wikimedia\Rdbms\DBConnectionError;
  25 use Wikimedia\Rdbms\DBError;
  26 use MediaWiki\MediaWikiServices;
  27 use Wikimedia\ScopedCallback;
  28
  29 /**
  30  * Class to handle job queues stored in the DB
  31  *
  32  * @ingroup JobQueue
  33  * @since 1.21
  34  */
  35 class JobQueueDB extends JobQueue {
  36         const CACHE_TTL_SHORT = 30; // integer; seconds to cache info without re-validating
  37         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed
  38         const MAX_JOB_RANDOM = 2147483647; // integer; 2^31 - 1, used for job_random
  39         const MAX_OFFSET = 255; // integer; maximum number of rows to skip
  40
  41         /** @var WANObjectCache */
  42         protected $cache;
  43         /** @var IDatabase|DBError|null */
  44         protected $conn;
  45
  46         /** @var array|null Server configuration array */
  47         protected $server;
  48         /** @var string|null Name of an external DB cluster or null for the local DB cluster */
  49         protected $cluster;
  50
  51         /**
  52          * Additional parameters include:
  53          *   - server  : Server configuration array for Database::factory. Overrides "cluster".
  54          *   - cluster : The name of an external cluster registered via LBFactory.
  55          *               If not specified, the primary DB cluster for the wiki will be used.
  56          *               This can be overridden with a custom cluster so that DB handles will
  57          *               be retrieved via LBFactory::getExternalLB() and getConnection().
  58          *   - wanCache : An instance of WANObjectCache to use for caching.
  59          * @param array $params
  60          */
  61         protected function __construct( array $params ) {
  62                 parent::__construct( $params );
  63
  64                 if ( isset( $params['server'] ) ) {
  65                         $this->server = $params['server'];
  66                 } elseif ( isset( $params['cluster'] ) && is_string( $params['cluster'] ) ) {
  67                         $this->cluster = $params['cluster'];
  68                 }
  69
  70                 $this->cache = $params['wanCache'] ?? WANObjectCache::newEmpty();
  71         }
  72
  73         protected function supportedOrders() {
  74                 return [ 'random', 'timestamp', 'fifo' ];
  75         }
  76
  77         protected function optimalOrder() {
  78                 return 'random';
  79         }
  80
  81         /**
  82          * @see JobQueue::doIsEmpty()
  83          * @return bool
  84          */
  85         protected function doIsEmpty() {
  86                 $dbr = $this->getReplicaDB();
  87                 /** @noinspection PhpUnusedLocalVariableInspection */
  88                 $scope = $this->getScopedNoTrxFlag( $dbr );
  89                 try {
  90                         $found = $dbr->selectField( // unclaimed job
  91                                 'job', '1', [ 'job_cmd' => $this->type, 'job_token' => '' ], __METHOD__
  92                         );
  93                 } catch ( DBError $e ) {
  94                         throw $this->getDBException( $e );
  95                 }
  96
  97                 return !$found;
  98         }
  99
 100         /**
 101          * @see JobQueue::doGetSize()
 102          * @return int
 103          */
 104         protected function doGetSize() {
 105                 $key = $this->getCacheKey( 'size' );
 106
 107                 $size = $this->cache->get( $key );
 108                 if ( is_int( $size ) ) {
 109                         return $size;
 110                 }
 111
 112                 $dbr = $this->getReplicaDB();
 113                 /** @noinspection PhpUnusedLocalVariableInspection */
 114                 $scope = $this->getScopedNoTrxFlag( $dbr );
 115                 try {
 116                         $size = (int)$dbr->selectField( 'job', 'COUNT(*)',
 117                                 [ 'job_cmd' => $this->type, 'job_token' => '' ],
 118                                 __METHOD__
 119                         );
 120                 } catch ( DBError $e ) {
 121                         throw $this->getDBException( $e );
 122                 }
 123                 $this->cache->set( $key, $size, self::CACHE_TTL_SHORT );
 124
 125                 return $size;
 126         }
 127
 128         /**
 129          * @see JobQueue::doGetAcquiredCount()
 130          * @return int
 131          */
 132         protected function doGetAcquiredCount() {
 133                 if ( $this->claimTTL <= 0 ) {
 134                         return 0; // no acknowledgements
 135                 }
 136
 137                 $key = $this->getCacheKey( 'acquiredcount' );
 138
 139                 $count = $this->cache->get( $key );
 140                 if ( is_int( $count ) ) {
 141                         return $count;
 142                 }
 143
 144                 $dbr = $this->getReplicaDB();
 145                 /** @noinspection PhpUnusedLocalVariableInspection */
 146                 $scope = $this->getScopedNoTrxFlag( $dbr );
 147                 try {
 148                         $count = (int)$dbr->selectField( 'job', 'COUNT(*)',
 149                                 [ 'job_cmd' => $this->type, "job_token != {$dbr->addQuotes( '' )}" ],
 150                                 __METHOD__
 151                         );
 152                 } catch ( DBError $e ) {
 153                         throw $this->getDBException( $e );
 154                 }
 155                 $this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
 156
 157                 return $count;
 158         }
 159
 160         /**
 161          * @see JobQueue::doGetAbandonedCount()
 162          * @return int
 163          * @throws MWException
 164          */
 165         protected function doGetAbandonedCount() {
 166                 if ( $this->claimTTL <= 0 ) {
 167                         return 0; // no acknowledgements
 168                 }
 169
 170                 $key = $this->getCacheKey( 'abandonedcount' );
 171
 172                 $count = $this->cache->get( $key );
 173                 if ( is_int( $count ) ) {
 174                         return $count;
 175                 }
 176
 177                 $dbr = $this->getReplicaDB();
 178                 /** @noinspection PhpUnusedLocalVariableInspection */
 179                 $scope = $this->getScopedNoTrxFlag( $dbr );
 180                 try {
 181                         $count = (int)$dbr->selectField( 'job', 'COUNT(*)',
 182                                 [
 183                                         'job_cmd' => $this->type,
 184                                         "job_token != {$dbr->addQuotes( '' )}",
 185                                         "job_attempts >= " . $dbr->addQuotes( $this->maxTries )
 186                                 ],
 187                                 __METHOD__
 188                         );
 189                 } catch ( DBError $e ) {
 190                         throw $this->getDBException( $e );
 191                 }
 192
 193                 $this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
 194
 195                 return $count;
 196         }
 197
 198         /**
 199          * @see JobQueue::doBatchPush()
 200          * @param IJobSpecification[] $jobs
 201          * @param int $flags
 202          * @throws DBError|Exception
 203          * @return void
 204          */
 205         protected function doBatchPush( array $jobs, $flags ) {
 206                 $dbw = $this->getMasterDB();
 207                 /** @noinspection PhpUnusedLocalVariableInspection */
 208                 $scope = $this->getScopedNoTrxFlag( $dbw );
 209                 // In general, there will be two cases here:
 210                 // a) sqlite; DB connection is probably a regular round-aware handle.
 211                 // If the connection is busy with a transaction, then defer the job writes
 212                 // until right before the main round commit step. Any errors that bubble
 213                 // up will rollback the main commit round.
 214                 // b) mysql/postgres; DB connection is generally a separate CONN_TRX_AUTOCOMMIT handle.
 215                 // No transaction is active nor will be started by writes, so enqueue the jobs
 216                 // now so that any errors will show up immediately as the interface expects. Any
 217                 // errors that bubble up will rollback the main commit round.
 218                 $fname = __METHOD__;
 219                 $dbw->onTransactionPreCommitOrIdle(
 220                         function ( IDatabase $dbw ) use ( $jobs, $flags, $fname ) {
 221                                 $this->doBatchPushInternal( $dbw, $jobs, $flags, $fname );
 222                         },
 223                         $fname
 224                 );
 225         }
 226
 227         /**
 228          * This function should *not* be called outside of JobQueueDB
 229          *
 230          * @suppress SecurityCheck-SQLInjection Bug in phan-taint-check handling bulk inserts
 231          * @param IDatabase $dbw
 232          * @param IJobSpecification[] $jobs
 233          * @param int $flags
 234          * @param string $method
 235          * @throws DBError
 236          * @return void
 237          */
 238         public function doBatchPushInternal( IDatabase $dbw, array $jobs, $flags, $method ) {
 239                 if ( $jobs === [] ) {
 240                         return;
 241                 }
 242
 243                 $rowSet = []; // (sha1 => job) map for jobs that are de-duplicated
 244                 $rowList = []; // list of jobs for jobs that are not de-duplicated
 245                 foreach ( $jobs as $job ) {
 246                         $row = $this->insertFields( $job, $dbw );
 247                         if ( $job->ignoreDuplicates() ) {
 248                                 $rowSet[$row['job_sha1']] = $row;
 249                         } else {
 250                                 $rowList[] = $row;
 251                         }
 252                 }
 253
 254                 if ( $flags & self::QOS_ATOMIC ) {
 255                         $dbw->startAtomic( $method ); // wrap all the job additions in one transaction
 256                 }
 257                 try {
 258                         // Strip out any duplicate jobs that are already in the queue...
 259                         if ( count( $rowSet ) ) {
 260                                 $res = $dbw->select( 'job', 'job_sha1',
 261                                         [
 262                                                 // No job_type condition since it's part of the job_sha1 hash
 263                                                 'job_sha1' => array_keys( $rowSet ),
 264                                                 'job_token' => '' // unclaimed
 265                                         ],
 266                                         $method
 267                                 );
 268                                 foreach ( $res as $row ) {
 269                                         wfDebug( "Job with hash '{$row->job_sha1}' is a duplicate.\n" );
 270                                         unset( $rowSet[$row->job_sha1] ); // already enqueued
 271                                 }
 272                         }
 273                         // Build the full list of job rows to insert
 274                         $rows = array_merge( $rowList, array_values( $rowSet ) );
 275                         // Insert the job rows in chunks to avoid replica DB lag...
 276                         foreach ( array_chunk( $rows, 50 ) as $rowBatch ) {
 277                                 $dbw->insert( 'job', $rowBatch, $method );
 278                         }
 279                         $this->incrStats( 'inserts', $this->type, count( $rows ) );
 280                         $this->incrStats( 'dupe_inserts', $this->type,
 281                                 count( $rowSet ) + count( $rowList ) - count( $rows )
 282                         );
 283                 } catch ( DBError $e ) {
 284                         throw $this->getDBException( $e );
 285                 }
 286                 if ( $flags & self::QOS_ATOMIC ) {
 287                         $dbw->endAtomic( $method );
 288                 }
 289         }
 290
 291         /**
 292          * @see JobQueue::doPop()
 293          * @return RunnableJob|bool
 294          */
 295         protected function doPop() {
 296                 $dbw = $this->getMasterDB();
 297                 /** @noinspection PhpUnusedLocalVariableInspection */
 298                 $scope = $this->getScopedNoTrxFlag( $dbw );
 299
 300                 $job = false; // job popped off
 301                 try {
 302                         $uuid = wfRandomString( 32 ); // pop attempt
 303                         do { // retry when our row is invalid or deleted as a duplicate
 304                                 // Try to reserve a row in the DB...
 305                                 if ( in_array( $this->order, [ 'fifo', 'timestamp' ] ) ) {
 306                                         $row = $this->claimOldest( $uuid );
 307                                 } else { // random first
 308                                         $rand = mt_rand( 0, self::MAX_JOB_RANDOM ); // encourage concurrent UPDATEs
 309                                         $gte = (bool)mt_rand( 0, 1 ); // find rows with rand before/after $rand
 310                                         $row = $this->claimRandom( $uuid, $rand, $gte );
 311                                 }
 312                                 // Check if we found a row to reserve...
 313                                 if ( !$row ) {
 314                                         break; // nothing to do
 315                                 }
 316                                 $this->incrStats( 'pops', $this->type );
 317
 318                                 // Get the job object from the row...
 319                                 $job = $this->jobFromRow( $row );
 320                                 break; // done
 321                         } while ( true );
 322
 323                         if ( !$job || mt_rand( 0, 9 ) == 0 ) {
 324                                 // Handled jobs that need to be recycled/deleted;
 325                                 // any recycled jobs will be picked up next attempt
 326                                 $this->recycleAndDeleteStaleJobs();
 327                         }
 328                 } catch ( DBError $e ) {
 329                         throw $this->getDBException( $e );
 330                 }
 331
 332                 return $job;
 333         }
 334
 335         /**
 336          * Reserve a row with a single UPDATE without holding row locks over RTTs...
 337          *
 338          * @param string $uuid 32 char hex string
 339          * @param int $rand Random unsigned integer (31 bits)
 340          * @param bool $gte Search for job_random >= $random (otherwise job_random <= $random)
 341          * @return stdClass|bool Row|false
 342          */
 343         protected function claimRandom( $uuid, $rand, $gte ) {
 344                 $dbw = $this->getMasterDB();
 345                 /** @noinspection PhpUnusedLocalVariableInspection */
 346                 $scope = $this->getScopedNoTrxFlag( $dbw );
 347                 // Check cache to see if the queue has <= OFFSET items
 348                 $tinyQueue = $this->cache->get( $this->getCacheKey( 'small' ) );
 349
 350                 $invertedDirection = false; // whether one job_random direction was already scanned
 351                 // This uses a replication safe method for acquiring jobs. One could use UPDATE+LIMIT
 352                 // instead, but that either uses ORDER BY (in which case it deadlocks in MySQL) or is
 353                 // not replication safe. Due to https://bugs.mysql.com/bug.php?id=6980, subqueries cannot
 354                 // be used here with MySQL.
 355                 do {
 356                         if ( $tinyQueue ) { // queue has <= MAX_OFFSET rows
 357                                 // For small queues, using OFFSET will overshoot and return no rows more often.
 358                                 // Instead, this uses job_random to pick a row (possibly checking both directions).
 359                                 $ineq = $gte ? '>=' : '<=';
 360                                 $dir = $gte ? 'ASC' : 'DESC';
 361                                 $row = $dbw->selectRow( 'job', self::selectFields(), // find a random job
 362                                         [
 363                                                 'job_cmd' => $this->type,
 364                                                 'job_token' => '', // unclaimed
 365                                                 "job_random {$ineq} {$dbw->addQuotes( $rand )}" ],
 366                                         __METHOD__,
 367                                         [ 'ORDER BY' => "job_random {$dir}" ]
 368                                 );
 369                                 if ( !$row && !$invertedDirection ) {
 370                                         $gte = !$gte;
 371                                         $invertedDirection = true;
 372                                         continue; // try the other direction
 373                                 }
 374                         } else { // table *may* have >= MAX_OFFSET rows
 375                                 // T44614: "ORDER BY job_random" with a job_random inequality causes high CPU
 376                                 // in MySQL if there are many rows for some reason. This uses a small OFFSET
 377                                 // instead of job_random for reducing excess claim retries.
 378                                 $row = $dbw->selectRow( 'job', self::selectFields(), // find a random job
 379                                         [
 380                                                 'job_cmd' => $this->type,
 381                                                 'job_token' => '', // unclaimed
 382                                         ],
 383                                         __METHOD__,
 384                                         [ 'OFFSET' => mt_rand( 0, self::MAX_OFFSET ) ]
 385                                 );
 386                                 if ( !$row ) {
 387                                         $tinyQueue = true; // we know the queue must have <= MAX_OFFSET rows
 388                                         $this->cache->set( $this->getCacheKey( 'small' ), 1, 30 );
 389                                         continue; // use job_random
 390                                 }
 391                         }
 392
 393                         if ( $row ) { // claim the job
 394                                 $dbw->update( 'job', // update by PK
 395                                         [
 396                                                 'job_token' => $uuid,
 397                                                 'job_token_timestamp' => $dbw->timestamp(),
 398                                                 'job_attempts = job_attempts+1' ],
 399                                         [ 'job_cmd' => $this->type, 'job_id' => $row->job_id, 'job_token' => '' ],
 400                                         __METHOD__
 401                                 );
 402                                 // This might get raced out by another runner when claiming the previously
 403                                 // selected row. The use of job_random should minimize this problem, however.
 404                                 if ( !$dbw->affectedRows() ) {
 405                                         $row = false; // raced out
 406                                 }
 407                         } else {
 408                                 break; // nothing to do
 409                         }
 410                 } while ( !$row );
 411
 412                 return $row;
 413         }
 414
 415         /**
 416          * Reserve a row with a single UPDATE without holding row locks over RTTs...
 417          *
 418          * @param string $uuid 32 char hex string
 419          * @return stdClass|bool Row|false
 420          */
 421         protected function claimOldest( $uuid ) {
 422                 $dbw = $this->getMasterDB();
 423                 /** @noinspection PhpUnusedLocalVariableInspection */
 424                 $scope = $this->getScopedNoTrxFlag( $dbw );
 425
 426                 $row = false; // the row acquired
 427                 do {
 428                         if ( $dbw->getType() === 'mysql' ) {
 429                                 // Per https://bugs.mysql.com/bug.php?id=6980, we can't use subqueries on the
 430                                 // same table being changed in an UPDATE query in MySQL (gives Error: 1093).
 431                                 // Oracle and Postgre have no such limitation. However, MySQL offers an
 432                                 // alternative here by supporting ORDER BY + LIMIT for UPDATE queries.
 433                                 $dbw->query( "UPDATE {$dbw->tableName( 'job' )} " .
 434                                         "SET " .
 435                                                 "job_token = {$dbw->addQuotes( $uuid ) }, " .
 436                                                 "job_token_timestamp = {$dbw->addQuotes( $dbw->timestamp() )}, " .
 437                                                 "job_attempts = job_attempts+1 " .
 438                                         "WHERE ( " .
 439                                                 "job_cmd = {$dbw->addQuotes( $this->type )} " .
 440                                                 "AND job_token = {$dbw->addQuotes( '' )} " .
 441                                         ") ORDER BY job_id ASC LIMIT 1",
 442                                         __METHOD__
 443                                 );
 444                         } else {
 445                                 // Use a subquery to find the job, within an UPDATE to claim it.
 446                                 // This uses as much of the DB wrapper functions as possible.
 447                                 $dbw->update( 'job',
 448                                         [
 449                                                 'job_token' => $uuid,
 450                                                 'job_token_timestamp' => $dbw->timestamp(),
 451                                                 'job_attempts = job_attempts+1' ],
 452                                         [ 'job_id = (' .
 453                                                 $dbw->selectSQLText( 'job', 'job_id',
 454                                                         [ 'job_cmd' => $this->type, 'job_token' => '' ],
 455                                                         __METHOD__,
 456                                                         [ 'ORDER BY' => 'job_id ASC', 'LIMIT' => 1 ] ) .
 457                                                 ')'
 458                                         ],
 459                                         __METHOD__
 460                                 );
 461                         }
 462                         // Fetch any row that we just reserved...
 463                         if ( $dbw->affectedRows() ) {
 464                                 $row = $dbw->selectRow( 'job', self::selectFields(),
 465                                         [ 'job_cmd' => $this->type, 'job_token' => $uuid ], __METHOD__
 466                                 );
 467                                 if ( !$row ) { // raced out by duplicate job removal
 468                                         wfDebug( "Row deleted as duplicate by another process.\n" );
 469                                 }
 470                         } else {
 471                                 break; // nothing to do
 472                         }
 473                 } while ( !$row );
 474
 475                 return $row;
 476         }
 477
 478         /**
 479          * @see JobQueue::doAck()
 480          * @param RunnableJob $job
 481          * @throws MWException
 482          */
 483         protected function doAck( RunnableJob $job ) {
 484                 $id = $job->getMetadata( 'id' );
 485                 if ( $id === null ) {
 486                         throw new MWException( "Job of type '{$job->getType()}' has no ID." );
 487                 }
 488
 489                 $dbw = $this->getMasterDB();
 490                 /** @noinspection PhpUnusedLocalVariableInspection */
 491                 $scope = $this->getScopedNoTrxFlag( $dbw );
 492                 try {
 493                         // Delete a row with a single DELETE without holding row locks over RTTs...
 494                         $dbw->delete(
 495                                 'job',
 496                                 [ 'job_cmd' => $this->type, 'job_id' => $id ],
 497                                 __METHOD__
 498                         );
 499
 500                         $this->incrStats( 'acks', $this->type );
 501                 } catch ( DBError $e ) {
 502                         throw $this->getDBException( $e );
 503                 }
 504         }
 505
 506         /**
 507          * @see JobQueue::doDeduplicateRootJob()
 508          * @param IJobSpecification $job
 509          * @throws MWException
 510          * @return bool
 511          */
 512         protected function doDeduplicateRootJob( IJobSpecification $job ) {
 513                 $params = $job->getParams();
 514                 if ( !isset( $params['rootJobSignature'] ) ) {
 515                         throw new MWException( "Cannot register root job; missing 'rootJobSignature'." );
 516                 } elseif ( !isset( $params['rootJobTimestamp'] ) ) {
 517                         throw new MWException( "Cannot register root job; missing 'rootJobTimestamp'." );
 518                 }
 519                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 520                 // Callers should call JobQueueGroup::push() before this method so that if the insert
 521                 // fails, the de-duplication registration will be aborted. Since the insert is
 522                 // deferred till "transaction idle", do the same here, so that the ordering is
 523                 // maintained. Having only the de-duplication registration succeed would cause
 524                 // jobs to become no-ops without any actual jobs that made them redundant.
 525                 $dbw = $this->getMasterDB();
 526                 /** @noinspection PhpUnusedLocalVariableInspection */
 527                 $scope = $this->getScopedNoTrxFlag( $dbw );
 528
 529                 $cache = $this->dupCache;
 530                 $dbw->onTransactionCommitOrIdle(
 531                         function () use ( $cache, $params, $key ) {
 532                                 $timestamp = $cache->get( $key ); // current last timestamp of this job
 533                                 if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 534                                         return true; // a newer version of this root job was enqueued
 535                                 }
 536
 537                                 // Update the timestamp of the last root job started at the location...
 538                                 return $cache->set( $key, $params['rootJobTimestamp'], JobQueueDB::ROOTJOB_TTL );
 539                         },
 540                         __METHOD__
 541                 );
 542
 543                 return true;
 544         }
 545
 546         /**
 547          * @see JobQueue::doDelete()
 548          * @return bool
 549          */
 550         protected function doDelete() {
 551                 $dbw = $this->getMasterDB();
 552                 /** @noinspection PhpUnusedLocalVariableInspection */
 553                 $scope = $this->getScopedNoTrxFlag( $dbw );
 554                 try {
 555                         $dbw->delete( 'job', [ 'job_cmd' => $this->type ] );
 556                 } catch ( DBError $e ) {
 557                         throw $this->getDBException( $e );
 558                 }
 559
 560                 return true;
 561         }
 562
 563         /**
 564          * @see JobQueue::doWaitForBackups()
 565          * @return void
 566          */
 567         protected function doWaitForBackups() {
 568                 if ( $this->server ) {
 569                         return; // not using LBFactory instance
 570                 }
 571
 572                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 573                 $lbFactory->waitForReplication( [
 574                         'domain' => $this->domain,
 575                         'cluster' => is_string( $this->cluster ) ? $this->cluster : false
 576                 ] );
 577         }
 578
 579         /**
 580          * @return void
 581          */
 582         protected function doFlushCaches() {
 583                 foreach ( [ 'size', 'acquiredcount' ] as $type ) {
 584                         $this->cache->delete( $this->getCacheKey( $type ) );
 585                 }
 586         }
 587
 588         /**
 589          * @see JobQueue::getAllQueuedJobs()
 590          * @return Iterator
 591          */
 592         public function getAllQueuedJobs() {
 593                 return $this->getJobIterator( [ 'job_cmd' => $this->getType(), 'job_token' => '' ] );
 594         }
 595
 596         /**
 597          * @see JobQueue::getAllAcquiredJobs()
 598          * @return Iterator
 599          */
 600         public function getAllAcquiredJobs() {
 601                 return $this->getJobIterator( [ 'job_cmd' => $this->getType(), "job_token > ''" ] );
 602         }
 603
 604         /**
 605          * @param array $conds Query conditions
 606          * @return Iterator
 607          */
 608         protected function getJobIterator( array $conds ) {
 609                 $dbr = $this->getReplicaDB();
 610                 /** @noinspection PhpUnusedLocalVariableInspection */
 611                 $scope = $this->getScopedNoTrxFlag( $dbr );
 612                 try {
 613                         return new MappedIterator(
 614                                 $dbr->select( 'job', self::selectFields(), $conds ),
 615                                 function ( $row ) {
 616                                         return $this->jobFromRow( $row );
 617                                 }
 618                         );
 619                 } catch ( DBError $e ) {
 620                         throw $this->getDBException( $e );
 621                 }
 622         }
 623
 624         public function getCoalesceLocationInternal() {
 625                 if ( $this->server ) {
 626                         return null; // not using the LBFactory instance
 627                 }
 628
 629                 return is_string( $this->cluster )
 630                         ? "DBCluster:{$this->cluster}:{$this->domain}"
 631                         : "LBFactory:{$this->domain}";
 632         }
 633
 634         protected function doGetSiblingQueuesWithJobs( array $types ) {
 635                 $dbr = $this->getReplicaDB();
 636                 /** @noinspection PhpUnusedLocalVariableInspection */
 637                 $scope = $this->getScopedNoTrxFlag( $dbr );
 638                 // @note: this does not check whether the jobs are claimed or not.
 639                 // This is useful so JobQueueGroup::pop() also sees queues that only
 640                 // have stale jobs. This lets recycleAndDeleteStaleJobs() re-enqueue
 641                 // failed jobs so that they can be popped again for that edge case.
 642                 $res = $dbr->select( 'job', 'DISTINCT job_cmd',
 643                         [ 'job_cmd' => $types ], __METHOD__ );
 644
 645                 $types = [];
 646                 foreach ( $res as $row ) {
 647                         $types[] = $row->job_cmd;
 648                 }
 649
 650                 return $types;
 651         }
 652
 653         protected function doGetSiblingQueueSizes( array $types ) {
 654                 $dbr = $this->getReplicaDB();
 655                 /** @noinspection PhpUnusedLocalVariableInspection */
 656                 $scope = $this->getScopedNoTrxFlag( $dbr );
 657
 658                 $res = $dbr->select( 'job', [ 'job_cmd', 'COUNT(*) AS count' ],
 659                         [ 'job_cmd' => $types ], __METHOD__, [ 'GROUP BY' => 'job_cmd' ] );
 660
 661                 $sizes = [];
 662                 foreach ( $res as $row ) {
 663                         $sizes[$row->job_cmd] = (int)$row->count;
 664                 }
 665
 666                 return $sizes;
 667         }
 668
 669         /**
 670          * Recycle or destroy any jobs that have been claimed for too long
 671          *
 672          * @return int Number of jobs recycled/deleted
 673          */
 674         public function recycleAndDeleteStaleJobs() {
 675                 $now = time();
 676                 $count = 0; // affected rows
 677                 $dbw = $this->getMasterDB();
 678                 /** @noinspection PhpUnusedLocalVariableInspection */
 679                 $scope = $this->getScopedNoTrxFlag( $dbw );
 680
 681                 try {
 682                         if ( !$dbw->lock( "jobqueue-recycle-{$this->type}", __METHOD__, 1 ) ) {
 683                                 return $count; // already in progress
 684                         }
 685
 686                         // Remove claims on jobs acquired for too long if enabled...
 687                         if ( $this->claimTTL > 0 ) {
 688                                 $claimCutoff = $dbw->timestamp( $now - $this->claimTTL );
 689                                 // Get the IDs of jobs that have be claimed but not finished after too long.
 690                                 // These jobs can be recycled into the queue by expiring the claim. Selecting
 691                                 // the IDs first means that the UPDATE can be done by primary key (less deadlocks).
 692                                 $res = $dbw->select( 'job', 'job_id',
 693                                         [
 694                                                 'job_cmd' => $this->type,
 695                                                 "job_token != {$dbw->addQuotes( '' )}", // was acquired
 696                                                 "job_token_timestamp < {$dbw->addQuotes( $claimCutoff )}", // stale
 697                                                 "job_attempts < {$dbw->addQuotes( $this->maxTries )}" ], // retries left
 698                                         __METHOD__
 699                                 );
 700                                 $ids = array_map(
 701                                         function ( $o ) {
 702                                                 return $o->job_id;
 703                                         }, iterator_to_array( $res )
 704                                 );
 705                                 if ( count( $ids ) ) {
 706                                         // Reset job_token for these jobs so that other runners will pick them up.
 707                                         // Set the timestamp to the current time, as it is useful to now that the job
 708                                         // was already tried before (the timestamp becomes the "released" time).
 709                                         $dbw->update( 'job',
 710                                                 [
 711                                                         'job_token' => '',
 712                                                         'job_token_timestamp' => $dbw->timestamp( $now ) ], // time of release
 713                                                 [
 714                                                         'job_id' => $ids ],
 715                                                 __METHOD__
 716                                         );
 717                                         $affected = $dbw->affectedRows();
 718                                         $count += $affected;
 719                                         $this->incrStats( 'recycles', $this->type, $affected );
 720                                 }
 721                         }
 722
 723                         // Just destroy any stale jobs...
 724                         $pruneCutoff = $dbw->timestamp( $now - self::MAX_AGE_PRUNE );
 725                         $conds = [
 726                                 'job_cmd' => $this->type,
 727                                 "job_token != {$dbw->addQuotes( '' )}", // was acquired
 728                                 "job_token_timestamp < {$dbw->addQuotes( $pruneCutoff )}" // stale
 729                         ];
 730                         if ( $this->claimTTL > 0 ) { // only prune jobs attempted too many times...
 731                                 $conds[] = "job_attempts >= {$dbw->addQuotes( $this->maxTries )}";
 732                         }
 733                         // Get the IDs of jobs that are considered stale and should be removed. Selecting
 734                         // the IDs first means that the UPDATE can be done by primary key (less deadlocks).
 735                         $res = $dbw->select( 'job', 'job_id', $conds, __METHOD__ );
 736                         $ids = array_map(
 737                                 function ( $o ) {
 738                                         return $o->job_id;
 739                                 }, iterator_to_array( $res )
 740                         );
 741                         if ( count( $ids ) ) {
 742                                 $dbw->delete( 'job', [ 'job_id' => $ids ], __METHOD__ );
 743                                 $affected = $dbw->affectedRows();
 744                                 $count += $affected;
 745                                 $this->incrStats( 'abandons', $this->type, $affected );
 746                         }
 747
 748                         $dbw->unlock( "jobqueue-recycle-{$this->type}", __METHOD__ );
 749                 } catch ( DBError $e ) {
 750                         throw $this->getDBException( $e );
 751                 }
 752
 753                 return $count;
 754         }
 755
 756         /**
 757          * @param IJobSpecification $job
 758          * @param IDatabase $db
 759          * @return array
 760          */
 761         protected function insertFields( IJobSpecification $job, IDatabase $db ) {
 762                 return [
 763                         // Fields that describe the nature of the job
 764                         'job_cmd' => $job->getType(),
 765                         'job_namespace' => $job->getParams()['namespace'] ?? NS_SPECIAL,
 766                         'job_title' => $job->getParams()['title'] ?? '',
 767                         'job_params' => self::makeBlob( $job->getParams() ),
 768                         // Additional job metadata
 769                         'job_timestamp' => $db->timestamp(),
 770                         'job_sha1' => Wikimedia\base_convert(
 771                                 sha1( serialize( $job->getDeduplicationInfo() ) ),
 772                                 16, 36, 31
 773                         ),
 774                         'job_random' => mt_rand( 0, self::MAX_JOB_RANDOM )
 775                 ];
 776         }
 777
 778         /**
 779          * @throws JobQueueConnectionError
 780          * @return IDatabase
 781          */
 782         protected function getReplicaDB() {
 783                 try {
 784                         return $this->getDB( DB_REPLICA );
 785                 } catch ( DBConnectionError $e ) {
 786                         throw new JobQueueConnectionError( "DBConnectionError:" . $e->getMessage() );
 787                 }
 788         }
 789
 790         /**
 791          * @throws JobQueueConnectionError
 792          * @return IDatabase
 793          */
 794         protected function getMasterDB() {
 795                 try {
 796                         return $this->getDB( DB_MASTER );
 797                 } catch ( DBConnectionError $e ) {
 798                         throw new JobQueueConnectionError( "DBConnectionError:" . $e->getMessage() );
 799                 }
 800         }
 801
 802         /**
 803          * @param int $index (DB_REPLICA/DB_MASTER)
 804          * @return IDatabase
 805          */
 806         protected function getDB( $index ) {
 807                 if ( $this->server ) {
 808                         if ( $this->conn instanceof IDatabase ) {
 809                                 return $this->conn;
 810                         } elseif ( $this->conn instanceof DBError ) {
 811                                 throw $this->conn;
 812                         }
 813
 814                         try {
 815                                 $this->conn = Database::factory( $this->server['type'], $this->server );
 816                         } catch ( DBError $e ) {
 817                                 $this->conn = $e;
 818                                 throw $e;
 819                         }
 820
 821                         return $this->conn;
 822                 } else {
 823                         $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 824                         $lb = is_string( $this->cluster )
 825                                 ? $lbFactory->getExternalLB( $this->cluster )
 826                                 : $lbFactory->getMainLB( $this->domain );
 827
 828                         return ( $lb->getServerType( $lb->getWriterIndex() ) !== 'sqlite' )
 829                                 // Keep a separate connection to avoid contention and deadlocks;
 830                                 // However, SQLite has the opposite behavior due to DB-level locking.
 831                                 ? $lb->getConnectionRef( $index, [], $this->domain, $lb::CONN_TRX_AUTOCOMMIT )
 832                                 // Jobs insertion will be defered until the PRESEND stage to reduce contention.
 833                                 : $lb->getConnectionRef( $index, [], $this->domain );
 834                 }
 835         }
 836
 837         /**
 838          * @param IDatabase $db
 839          * @return ScopedCallback
 840          */
 841         private function getScopedNoTrxFlag( IDatabase $db ) {
 842                 $autoTrx = $db->getFlag( DBO_TRX ); // get current setting
 843                 $db->clearFlag( DBO_TRX ); // make each query its own transaction
 844
 845                 return new ScopedCallback( function () use ( $db, $autoTrx ) {
 846                         if ( $autoTrx ) {
 847                                 $db->setFlag( DBO_TRX ); // restore old setting
 848                         }
 849                 } );
 850         }
 851
 852         /**
 853          * @param string $property
 854          * @return string
 855          */
 856         private function getCacheKey( $property ) {
 857                 $cluster = is_string( $this->cluster ) ? $this->cluster : 'main';
 858
 859                 return $this->cache->makeGlobalKey(
 860                         'jobqueue',
 861                         $this->domain,
 862                         $cluster,
 863                         $this->type,
 864                         $property
 865                 );
 866         }
 867
 868         /**
 869          * @param array|bool $params
 870          * @return string
 871          */
 872         protected static function makeBlob( $params ) {
 873                 if ( $params !== false ) {
 874                         return serialize( $params );
 875                 } else {
 876                         return '';
 877                 }
 878         }
 879
 880         /**
 881          * @param stdClass $row
 882          * @return RunnableJob|null
 883          */
 884         protected function jobFromRow( $row ) {
 885                 $params = ( (string)$row->job_params !== '' ) ? unserialize( $row->job_params ) : [];
 886                 if ( !is_array( $params ) ) { // this shouldn't happen
 887                         throw new UnexpectedValueException(
 888                                 "Could not unserialize job with ID '{$row->job_id}'." );
 889                 }
 890
 891                 $params += [ 'namespace' => $row->job_namespace, 'title' => $row->job_title ];
 892                 $job = $this->factoryJob( $row->job_cmd, $params );
 893                 $job->setMetadata( 'id', $row->job_id );
 894                 $job->setMetadata( 'timestamp', $row->job_timestamp );
 895
 896                 return $job;
 897         }
 898
 899         /**
 900          * @param DBError $e
 901          * @return JobQueueError
 902          */
 903         protected function getDBException( DBError $e ) {
 904                 return new JobQueueError( get_class( $e ) . ": " . $e->getMessage() );
 905         }
 906
 907         /**
 908          * Return the list of job fields that should be selected.
 909          * @since 1.23
 910          * @return array
 911          */
 912         public static function selectFields() {
 913                 return [
 914                         'job_id',
 915                         'job_cmd',
 916                         'job_namespace',
 917                         'job_title',
 918                         'job_timestamp',
 919                         'job_params',
 920                         'job_random',
 921                         'job_attempts',
 922                         'job_token',
 923                         'job_token_timestamp',
 924                         'job_sha1',
 925                 ];
 926         }
 927 }