includes/jobqueue/JobQueue.php

   1 <?php
   2 /**
   3  * Job queue base 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  * @defgroup JobQueue JobQueue
  22  */
  23 use MediaWiki\MediaWikiServices;
  24
  25 /**
  26  * Class to handle enqueueing and running of background jobs
  27  *
  28  * @ingroup JobQueue
  29  * @since 1.21
  30  */
  31 abstract class JobQueue {
  32         /** @var string Wiki ID */
  33         protected $wiki;
  34         /** @var string Job type */
  35         protected $type;
  36         /** @var string Job priority for pop() */
  37         protected $order;
  38         /** @var int Time to live in seconds */
  39         protected $claimTTL;
  40         /** @var int Maximum number of times to try a job */
  41         protected $maxTries;
  42         /** @var string|bool Read only rationale (or false if r/w) */
  43         protected $readOnlyReason;
  44
  45         /** @var BagOStuff */
  46         protected $dupCache;
  47         /** @var JobQueueAggregator */
  48         protected $aggr;
  49
  50         const QOS_ATOMIC = 1; // integer; "all-or-nothing" job insertions
  51
  52         const ROOTJOB_TTL = 2419200; // integer; seconds to remember root jobs (28 days)
  53
  54         /**
  55          * @param array $params
  56          * @throws MWException
  57          */
  58         protected function __construct( array $params ) {
  59                 $this->wiki = $params['wiki'];
  60                 $this->type = $params['type'];
  61                 $this->claimTTL = isset( $params['claimTTL'] ) ? $params['claimTTL'] : 0;
  62                 $this->maxTries = isset( $params['maxTries'] ) ? $params['maxTries'] : 3;
  63                 if ( isset( $params['order'] ) && $params['order'] !== 'any' ) {
  64                         $this->order = $params['order'];
  65                 } else {
  66                         $this->order = $this->optimalOrder();
  67                 }
  68                 if ( !in_array( $this->order, $this->supportedOrders() ) ) {
  69                         throw new MWException( __CLASS__ . " does not support '{$this->order}' order." );
  70                 }
  71                 $this->dupCache = wfGetCache( CACHE_ANYTHING );
  72                 $this->aggr = isset( $params['aggregator'] )
  73                         ? $params['aggregator']
  74                         : new JobQueueAggregatorNull( [] );
  75                 $this->readOnlyReason = isset( $params['readOnlyReason'] )
  76                         ? $params['readOnlyReason']
  77                         : false;
  78         }
  79
  80         /**
  81          * Get a job queue object of the specified type.
  82          * $params includes:
  83          *   - class      : What job class to use (determines job type)
  84          *   - wiki       : wiki ID of the wiki the jobs are for (defaults to current wiki)
  85          *   - type       : The name of the job types this queue handles
  86          *   - order      : Order that pop() selects jobs, one of "fifo", "timestamp" or "random".
  87          *                  If "fifo" is used, the queue will effectively be FIFO. Note that job
  88          *                  completion will not appear to be exactly FIFO if there are multiple
  89          *                  job runners since jobs can take different times to finish once popped.
  90          *                  If "timestamp" is used, the queue will at least be loosely ordered
  91          *                  by timestamp, allowing for some jobs to be popped off out of order.
  92          *                  If "random" is used, pop() will pick jobs in random order.
  93          *                  Note that it may only be weakly random (e.g. a lottery of the oldest X).
  94          *                  If "any" is choosen, the queue will use whatever order is the fastest.
  95          *                  This might be useful for improving concurrency for job acquisition.
  96          *   - claimTTL   : If supported, the queue will recycle jobs that have been popped
  97          *                  but not acknowledged as completed after this many seconds. Recycling
  98          *                  of jobs simply means re-inserting them into the queue. Jobs can be
  99          *                  attempted up to three times before being discarded.
 100          *   - readOnlyReason : Set this to a string to make the queue read-only.
 101          *
 102          * Queue classes should throw an exception if they do not support the options given.
 103          *
 104          * @param array $params
 105          * @return JobQueue
 106          * @throws MWException
 107          */
 108         final public static function factory( array $params ) {
 109                 $class = $params['class'];
 110                 if ( !class_exists( $class ) ) {
 111                         throw new MWException( "Invalid job queue class '$class'." );
 112                 }
 113                 $obj = new $class( $params );
 114                 if ( !( $obj instanceof self ) ) {
 115                         throw new MWException( "Class '$class' is not a " . __CLASS__ . " class." );
 116                 }
 117
 118                 return $obj;
 119         }
 120
 121         /**
 122          * @return string Wiki ID
 123          */
 124         final public function getWiki() {
 125                 return $this->wiki;
 126         }
 127
 128         /**
 129          * @return string Job type that this queue handles
 130          */
 131         final public function getType() {
 132                 return $this->type;
 133         }
 134
 135         /**
 136          * @return string One of (random, timestamp, fifo, undefined)
 137          */
 138         final public function getOrder() {
 139                 return $this->order;
 140         }
 141
 142         /**
 143          * Get the allowed queue orders for configuration validation
 144          *
 145          * @return array Subset of (random, timestamp, fifo, undefined)
 146          */
 147         abstract protected function supportedOrders();
 148
 149         /**
 150          * Get the default queue order to use if configuration does not specify one
 151          *
 152          * @return string One of (random, timestamp, fifo, undefined)
 153          */
 154         abstract protected function optimalOrder();
 155
 156         /**
 157          * Find out if delayed jobs are supported for configuration validation
 158          *
 159          * @return bool Whether delayed jobs are supported
 160          */
 161         protected function supportsDelayedJobs() {
 162                 return false; // not implemented
 163         }
 164
 165         /**
 166          * @return bool Whether delayed jobs are enabled
 167          * @since 1.22
 168          */
 169         final public function delayedJobsEnabled() {
 170                 return $this->supportsDelayedJobs();
 171         }
 172
 173         /**
 174          * @return string|bool Read-only rational or false if r/w
 175          * @since 1.27
 176          */
 177         public function getReadOnlyReason() {
 178                 return $this->readOnlyReason;
 179         }
 180
 181         /**
 182          * Quickly check if the queue has no available (unacquired, non-delayed) jobs.
 183          * Queue classes should use caching if they are any slower without memcached.
 184          *
 185          * If caching is used, this might return false when there are actually no jobs.
 186          * If pop() is called and returns false then it should correct the cache. Also,
 187          * calling flushCaches() first prevents this. However, this affect is typically
 188          * not distinguishable from the race condition between isEmpty() and pop().
 189          *
 190          * @return bool
 191          * @throws JobQueueError
 192          */
 193         final public function isEmpty() {
 194                 $res = $this->doIsEmpty();
 195
 196                 return $res;
 197         }
 198
 199         /**
 200          * @see JobQueue::isEmpty()
 201          * @return bool
 202          */
 203         abstract protected function doIsEmpty();
 204
 205         /**
 206          * Get the number of available (unacquired, non-delayed) jobs in the queue.
 207          * Queue classes should use caching if they are any slower without memcached.
 208          *
 209          * If caching is used, this number might be out of date for a minute.
 210          *
 211          * @return int
 212          * @throws JobQueueError
 213          */
 214         final public function getSize() {
 215                 $res = $this->doGetSize();
 216
 217                 return $res;
 218         }
 219
 220         /**
 221          * @see JobQueue::getSize()
 222          * @return int
 223          */
 224         abstract protected function doGetSize();
 225
 226         /**
 227          * Get the number of acquired jobs (these are temporarily out of the queue).
 228          * Queue classes should use caching if they are any slower without memcached.
 229          *
 230          * If caching is used, this number might be out of date for a minute.
 231          *
 232          * @return int
 233          * @throws JobQueueError
 234          */
 235         final public function getAcquiredCount() {
 236                 $res = $this->doGetAcquiredCount();
 237
 238                 return $res;
 239         }
 240
 241         /**
 242          * @see JobQueue::getAcquiredCount()
 243          * @return int
 244          */
 245         abstract protected function doGetAcquiredCount();
 246
 247         /**
 248          * Get the number of delayed jobs (these are temporarily out of the queue).
 249          * Queue classes should use caching if they are any slower without memcached.
 250          *
 251          * If caching is used, this number might be out of date for a minute.
 252          *
 253          * @return int
 254          * @throws JobQueueError
 255          * @since 1.22
 256          */
 257         final public function getDelayedCount() {
 258                 $res = $this->doGetDelayedCount();
 259
 260                 return $res;
 261         }
 262
 263         /**
 264          * @see JobQueue::getDelayedCount()
 265          * @return int
 266          */
 267         protected function doGetDelayedCount() {
 268                 return 0; // not implemented
 269         }
 270
 271         /**
 272          * Get the number of acquired jobs that can no longer be attempted.
 273          * Queue classes should use caching if they are any slower without memcached.
 274          *
 275          * If caching is used, this number might be out of date for a minute.
 276          *
 277          * @return int
 278          * @throws JobQueueError
 279          */
 280         final public function getAbandonedCount() {
 281                 $res = $this->doGetAbandonedCount();
 282
 283                 return $res;
 284         }
 285
 286         /**
 287          * @see JobQueue::getAbandonedCount()
 288          * @return int
 289          */
 290         protected function doGetAbandonedCount() {
 291                 return 0; // not implemented
 292         }
 293
 294         /**
 295          * Push one or more jobs into the queue.
 296          * This does not require $wgJobClasses to be set for the given job type.
 297          * Outside callers should use JobQueueGroup::push() instead of this function.
 298          *
 299          * @param IJobSpecification|IJobSpecification[] $jobs
 300          * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
 301          * @return void
 302          * @throws JobQueueError
 303          */
 304         final public function push( $jobs, $flags = 0 ) {
 305                 $jobs = is_array( $jobs ) ? $jobs : [ $jobs ];
 306                 $this->batchPush( $jobs, $flags );
 307         }
 308
 309         /**
 310          * Push a batch of jobs into the queue.
 311          * This does not require $wgJobClasses to be set for the given job type.
 312          * Outside callers should use JobQueueGroup::push() instead of this function.
 313          *
 314          * @param IJobSpecification[] $jobs
 315          * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
 316          * @return void
 317          * @throws MWException
 318          */
 319         final public function batchPush( array $jobs, $flags = 0 ) {
 320                 $this->assertNotReadOnly();
 321
 322                 if ( !count( $jobs ) ) {
 323                         return; // nothing to do
 324                 }
 325
 326                 foreach ( $jobs as $job ) {
 327                         if ( $job->getType() !== $this->type ) {
 328                                 throw new MWException(
 329                                         "Got '{$job->getType()}' job; expected a '{$this->type}' job." );
 330                         } elseif ( $job->getReleaseTimestamp() && !$this->supportsDelayedJobs() ) {
 331                                 throw new MWException(
 332                                         "Got delayed '{$job->getType()}' job; delays are not supported." );
 333                         }
 334                 }
 335
 336                 $this->doBatchPush( $jobs, $flags );
 337                 $this->aggr->notifyQueueNonEmpty( $this->wiki, $this->type );
 338
 339                 foreach ( $jobs as $job ) {
 340                         if ( $job->isRootJob() ) {
 341                                 $this->deduplicateRootJob( $job );
 342                         }
 343                 }
 344         }
 345
 346         /**
 347          * @see JobQueue::batchPush()
 348          * @param IJobSpecification[] $jobs
 349          * @param int $flags
 350          */
 351         abstract protected function doBatchPush( array $jobs, $flags );
 352
 353         /**
 354          * Pop a job off of the queue.
 355          * This requires $wgJobClasses to be set for the given job type.
 356          * Outside callers should use JobQueueGroup::pop() instead of this function.
 357          *
 358          * @throws MWException
 359          * @return Job|bool Returns false if there are no jobs
 360          */
 361         final public function pop() {
 362                 global $wgJobClasses;
 363
 364                 $this->assertNotReadOnly();
 365                 if ( $this->wiki !== wfWikiID() ) {
 366                         throw new MWException( "Cannot pop '{$this->type}' job off foreign wiki queue." );
 367                 } elseif ( !isset( $wgJobClasses[$this->type] ) ) {
 368                         // Do not pop jobs if there is no class for the queue type
 369                         throw new MWException( "Unrecognized job type '{$this->type}'." );
 370                 }
 371
 372                 $job = $this->doPop();
 373
 374                 if ( !$job ) {
 375                         $this->aggr->notifyQueueEmpty( $this->wiki, $this->type );
 376                 }
 377
 378                 // Flag this job as an old duplicate based on its "root" job...
 379                 try {
 380                         if ( $job && $this->isRootJobOldDuplicate( $job ) ) {
 381                                 self::incrStats( 'dupe_pops', $this->type );
 382                                 $job = DuplicateJob::newFromJob( $job ); // convert to a no-op
 383                         }
 384                 } catch ( Exception $e ) {
 385                         // don't lose jobs over this
 386                 }
 387
 388                 return $job;
 389         }
 390
 391         /**
 392          * @see JobQueue::pop()
 393          * @return Job|bool
 394          */
 395         abstract protected function doPop();
 396
 397         /**
 398          * Acknowledge that a job was completed.
 399          *
 400          * This does nothing for certain queue classes or if "claimTTL" is not set.
 401          * Outside callers should use JobQueueGroup::ack() instead of this function.
 402          *
 403          * @param Job $job
 404          * @return void
 405          * @throws MWException
 406          */
 407         final public function ack( Job $job ) {
 408                 $this->assertNotReadOnly();
 409                 if ( $job->getType() !== $this->type ) {
 410                         throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 411                 }
 412
 413                 $this->doAck( $job );
 414         }
 415
 416         /**
 417          * @see JobQueue::ack()
 418          * @param Job $job
 419          */
 420         abstract protected function doAck( Job $job );
 421
 422         /**
 423          * Register the "root job" of a given job into the queue for de-duplication.
 424          * This should only be called right *after* all the new jobs have been inserted.
 425          * This is used to turn older, duplicate, job entries into no-ops. The root job
 426          * information will remain in the registry until it simply falls out of cache.
 427          *
 428          * This requires that $job has two special fields in the "params" array:
 429          *   - rootJobSignature : hash (e.g. SHA1) that identifies the task
 430          *   - rootJobTimestamp : TS_MW timestamp of this instance of the task
 431          *
 432          * A "root job" is a conceptual job that consist of potentially many smaller jobs
 433          * that are actually inserted into the queue. For example, "refreshLinks" jobs are
 434          * spawned when a template is edited. One can think of the task as "update links
 435          * of pages that use template X" and an instance of that task as a "root job".
 436          * However, what actually goes into the queue are range and leaf job subtypes.
 437          * Since these jobs include things like page ID ranges and DB master positions,
 438          * and can morph into smaller jobs recursively, simple duplicate detection
 439          * for individual jobs being identical (like that of job_sha1) is not useful.
 440          *
 441          * In the case of "refreshLinks", if these jobs are still in the queue when the template
 442          * is edited again, we want all of these old refreshLinks jobs for that template to become
 443          * no-ops. This can greatly reduce server load, since refreshLinks jobs involves parsing.
 444          * Essentially, the new batch of jobs belong to a new "root job" and the older ones to a
 445          * previous "root job" for the same task of "update links of pages that use template X".
 446          *
 447          * This does nothing for certain queue classes.
 448          *
 449          * @param IJobSpecification $job
 450          * @throws MWException
 451          * @return bool
 452          */
 453         final public function deduplicateRootJob( IJobSpecification $job ) {
 454                 $this->assertNotReadOnly();
 455                 if ( $job->getType() !== $this->type ) {
 456                         throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 457                 }
 458
 459                 return $this->doDeduplicateRootJob( $job );
 460         }
 461
 462         /**
 463          * @see JobQueue::deduplicateRootJob()
 464          * @param IJobSpecification $job
 465          * @throws MWException
 466          * @return bool
 467          */
 468         protected function doDeduplicateRootJob( IJobSpecification $job ) {
 469                 if ( !$job->hasRootJobParams() ) {
 470                         throw new MWException( "Cannot register root job; missing parameters." );
 471                 }
 472                 $params = $job->getRootJobParams();
 473
 474                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 475                 // Callers should call batchInsert() and then this function so that if the insert
 476                 // fails, the de-duplication registration will be aborted. Since the insert is
 477                 // deferred till "transaction idle", do the same here, so that the ordering is
 478                 // maintained. Having only the de-duplication registration succeed would cause
 479                 // jobs to become no-ops without any actual jobs that made them redundant.
 480                 $timestamp = $this->dupCache->get( $key ); // current last timestamp of this job
 481                 if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 482                         return true; // a newer version of this root job was enqueued
 483                 }
 484
 485                 // Update the timestamp of the last root job started at the location...
 486                 return $this->dupCache->set( $key, $params['rootJobTimestamp'], JobQueueDB::ROOTJOB_TTL );
 487         }
 488
 489         /**
 490          * Check if the "root" job of a given job has been superseded by a newer one
 491          *
 492          * @param Job $job
 493          * @throws MWException
 494          * @return bool
 495          */
 496         final protected function isRootJobOldDuplicate( Job $job ) {
 497                 if ( $job->getType() !== $this->type ) {
 498                         throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 499                 }
 500                 $isDuplicate = $this->doIsRootJobOldDuplicate( $job );
 501
 502                 return $isDuplicate;
 503         }
 504
 505         /**
 506          * @see JobQueue::isRootJobOldDuplicate()
 507          * @param Job $job
 508          * @return bool
 509          */
 510         protected function doIsRootJobOldDuplicate( Job $job ) {
 511                 if ( !$job->hasRootJobParams() ) {
 512                         return false; // job has no de-deplication info
 513                 }
 514                 $params = $job->getRootJobParams();
 515
 516                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 517                 // Get the last time this root job was enqueued
 518                 $timestamp = $this->dupCache->get( $key );
 519
 520                 // Check if a new root job was started at the location after this one's...
 521                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 522         }
 523
 524         /**
 525          * @param string $signature Hash identifier of the root job
 526          * @return string
 527          */
 528         protected function getRootJobCacheKey( $signature ) {
 529                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 530
 531                 return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, 'rootjob', $signature );
 532         }
 533
 534         /**
 535          * Deleted all unclaimed and delayed jobs from the queue
 536          *
 537          * @throws JobQueueError
 538          * @since 1.22
 539          * @return void
 540          */
 541         final public function delete() {
 542                 $this->assertNotReadOnly();
 543
 544                 $this->doDelete();
 545         }
 546
 547         /**
 548          * @see JobQueue::delete()
 549          * @throws MWException
 550          */
 551         protected function doDelete() {
 552                 throw new MWException( "This method is not implemented." );
 553         }
 554
 555         /**
 556          * Wait for any replica DBs or backup servers to catch up.
 557          *
 558          * This does nothing for certain queue classes.
 559          *
 560          * @return void
 561          * @throws JobQueueError
 562          */
 563         final public function waitForBackups() {
 564                 $this->doWaitForBackups();
 565         }
 566
 567         /**
 568          * @see JobQueue::waitForBackups()
 569          * @return void
 570          */
 571         protected function doWaitForBackups() {
 572         }
 573
 574         /**
 575          * Clear any process and persistent caches
 576          *
 577          * @return void
 578          */
 579         final public function flushCaches() {
 580                 $this->doFlushCaches();
 581         }
 582
 583         /**
 584          * @see JobQueue::flushCaches()
 585          * @return void
 586          */
 587         protected function doFlushCaches() {
 588         }
 589
 590         /**
 591          * Get an iterator to traverse over all available jobs in this queue.
 592          * This does not include jobs that are currently acquired or delayed.
 593          * Note: results may be stale if the queue is concurrently modified.
 594          *
 595          * @return Iterator
 596          * @throws JobQueueError
 597          */
 598         abstract public function getAllQueuedJobs();
 599
 600         /**
 601          * Get an iterator to traverse over all delayed jobs in this queue.
 602          * Note: results may be stale if the queue is concurrently modified.
 603          *
 604          * @return Iterator
 605          * @throws JobQueueError
 606          * @since 1.22
 607          */
 608         public function getAllDelayedJobs() {
 609                 return new ArrayIterator( [] ); // not implemented
 610         }
 611
 612         /**
 613          * Get an iterator to traverse over all claimed jobs in this queue
 614          *
 615          * Callers should be quick to iterator over it or few results
 616          * will be returned due to jobs being acknowledged and deleted
 617          *
 618          * @return Iterator
 619          * @throws JobQueueError
 620          * @since 1.26
 621          */
 622         public function getAllAcquiredJobs() {
 623                 return new ArrayIterator( [] ); // not implemented
 624         }
 625
 626         /**
 627          * Get an iterator to traverse over all abandoned jobs in this queue
 628          *
 629          * @return Iterator
 630          * @throws JobQueueError
 631          * @since 1.25
 632          */
 633         public function getAllAbandonedJobs() {
 634                 return new ArrayIterator( [] ); // not implemented
 635         }
 636
 637         /**
 638          * Do not use this function outside of JobQueue/JobQueueGroup
 639          *
 640          * @return string
 641          * @since 1.22
 642          */
 643         public function getCoalesceLocationInternal() {
 644                 return null;
 645         }
 646
 647         /**
 648          * Check whether each of the given queues are empty.
 649          * This is used for batching checks for queues stored at the same place.
 650          *
 651          * @param array $types List of queues types
 652          * @return array|null (list of non-empty queue types) or null if unsupported
 653          * @throws MWException
 654          * @since 1.22
 655          */
 656         final public function getSiblingQueuesWithJobs( array $types ) {
 657                 return $this->doGetSiblingQueuesWithJobs( $types );
 658         }
 659
 660         /**
 661          * @see JobQueue::getSiblingQueuesWithJobs()
 662          * @param array $types List of queues types
 663          * @return array|null (list of queue types) or null if unsupported
 664          */
 665         protected function doGetSiblingQueuesWithJobs( array $types ) {
 666                 return null; // not supported
 667         }
 668
 669         /**
 670          * Check the size of each of the given queues.
 671          * For queues not served by the same store as this one, 0 is returned.
 672          * This is used for batching checks for queues stored at the same place.
 673          *
 674          * @param array $types List of queues types
 675          * @return array|null (job type => whether queue is empty) or null if unsupported
 676          * @throws MWException
 677          * @since 1.22
 678          */
 679         final public function getSiblingQueueSizes( array $types ) {
 680                 return $this->doGetSiblingQueueSizes( $types );
 681         }
 682
 683         /**
 684          * @see JobQueue::getSiblingQueuesSize()
 685          * @param array $types List of queues types
 686          * @return array|null (list of queue types) or null if unsupported
 687          */
 688         protected function doGetSiblingQueueSizes( array $types ) {
 689                 return null; // not supported
 690         }
 691
 692         /**
 693          * @throws JobQueueReadOnlyError
 694          */
 695         protected function assertNotReadOnly() {
 696                 if ( $this->readOnlyReason !== false ) {
 697                         throw new JobQueueReadOnlyError( "Job queue is read-only: {$this->readOnlyReason}" );
 698                 }
 699         }
 700
 701         /**
 702          * Call wfIncrStats() for the queue overall and for the queue type
 703          *
 704          * @param string $key Event type
 705          * @param string $type Job type
 706          * @param int $delta
 707          * @since 1.22
 708          */
 709         public static function incrStats( $key, $type, $delta = 1 ) {
 710                 static $stats;
 711                 if ( !$stats ) {
 712                         $stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
 713                 }
 714                 $stats->updateCount( "jobqueue.{$key}.all", $delta );
 715                 $stats->updateCount( "jobqueue.{$key}.{$type}", $delta );
 716         }
 717 }
 718
 719 /**
 720  * @ingroup JobQueue
 721  * @since 1.22
 722  */
 723 class JobQueueError extends MWException {
 724 }
 725
 726 class JobQueueConnectionError extends JobQueueError {
 727 }
 728
 729 class JobQueueReadOnlyError extends JobQueueError {
 730
 731 }