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 Liuggio\StatsdClient\Factory\StatsdDataFactoryInterface;
  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 DB domain ID */
  33         protected $domain;
  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         /** @var StatsdDataFactoryInterface */
  45         protected $stats;
  46
  47         /** @var WANObjectCache */
  48         protected $wanCache;
  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          *       - type           : A job type
  57          *   - domain         : A DB domain ID
  58          *   - wanCache       : An instance of WANObjectCache to use for caching [default: none]
  59          *   - stats          : An instance of StatsdDataFactoryInterface [default: none]
  60          *   - claimTTL       : Seconds a job can be claimed for exclusive execution [default: forever]
  61          *   - maxTries       : Total times a job can be tried, assuming claims expire [default: 3]
  62          *   - order          : Queue order, one of ("fifo", "timestamp", "random") [default: variable]
  63          *   - readOnlyReason : Mark the queue as read-only with this reason [default: false]
  64          * @throws JobQueueError
  65          */
  66         protected function __construct( array $params ) {
  67                 $this->domain = $params['domain'] ?? $params['wiki']; // b/c
  68                 $this->type = $params['type'];
  69                 $this->claimTTL = $params['claimTTL'] ?? 0;
  70                 $this->maxTries = $params['maxTries'] ?? 3;
  71                 if ( isset( $params['order'] ) && $params['order'] !== 'any' ) {
  72                         $this->order = $params['order'];
  73                 } else {
  74                         $this->order = $this->optimalOrder();
  75                 }
  76                 if ( !in_array( $this->order, $this->supportedOrders() ) ) {
  77                         throw new JobQueueError( __CLASS__ . " does not support '{$this->order}' order." );
  78                 }
  79                 $this->readOnlyReason = $params['readOnlyReason'] ?? false;
  80                 $this->stats = $params['stats'] ?? new NullStatsdDataFactory();
  81                 $this->wanCache = $params['wanCache'] ?? WANObjectCache::newEmpty();
  82         }
  83
  84         /**
  85          * Get a job queue object of the specified type.
  86          * $params includes:
  87          *   - class      : What job class to use (determines job type)
  88          *   - domain     : Database domain ID of the wiki the jobs are for (defaults to current wiki)
  89          *   - type       : The name of the job types this queue handles
  90          *   - order      : Order that pop() selects jobs, one of "fifo", "timestamp" or "random".
  91          *                  If "fifo" is used, the queue will effectively be FIFO. Note that job
  92          *                  completion will not appear to be exactly FIFO if there are multiple
  93          *                  job runners since jobs can take different times to finish once popped.
  94          *                  If "timestamp" is used, the queue will at least be loosely ordered
  95          *                  by timestamp, allowing for some jobs to be popped off out of order.
  96          *                  If "random" is used, pop() will pick jobs in random order.
  97          *                  Note that it may only be weakly random (e.g. a lottery of the oldest X).
  98          *                  If "any" is choosen, the queue will use whatever order is the fastest.
  99          *                  This might be useful for improving concurrency for job acquisition.
 100          *   - claimTTL   : If supported, the queue will recycle jobs that have been popped
 101          *                  but not acknowledged as completed after this many seconds. Recycling
 102          *                  of jobs simply means re-inserting them into the queue. Jobs can be
 103          *                  attempted up to three times before being discarded.
 104          *   - readOnlyReason : Set this to a string to make the queue read-only.
 105          *   - stash      : A BagOStuff instance that can be used for root job deduplication
 106          *   - stats      : A StatsdDataFactoryInterface [optional]
 107          *
 108          * Queue classes should throw an exception if they do not support the options given.
 109          *
 110          * @param array $params
 111          * @return JobQueue
 112          * @throws JobQueueError
 113          */
 114         final public static function factory( array $params ) {
 115                 $class = $params['class'];
 116                 if ( !class_exists( $class ) ) {
 117                         throw new JobQueueError( "Invalid job queue class '$class'." );
 118                 }
 119                 $obj = new $class( $params );
 120                 if ( !( $obj instanceof self ) ) {
 121                         throw new JobQueueError( "Class '$class' is not a " . __CLASS__ . " class." );
 122                 }
 123
 124                 return $obj;
 125         }
 126
 127         /**
 128          * @return string Database domain ID
 129          */
 130         final public function getDomain() {
 131                 return $this->domain;
 132         }
 133
 134         /**
 135          * @return string Wiki ID
 136          * @deprecated 1.33
 137          */
 138         final public function getWiki() {
 139                 return WikiMap::getWikiIdFromDbDomain( $this->domain );
 140         }
 141
 142         /**
 143          * @return string Job type that this queue handles
 144          */
 145         final public function getType() {
 146                 return $this->type;
 147         }
 148
 149         /**
 150          * @return string One of (random, timestamp, fifo, undefined)
 151          */
 152         final public function getOrder() {
 153                 return $this->order;
 154         }
 155
 156         /**
 157          * Get the allowed queue orders for configuration validation
 158          *
 159          * @return array Subset of (random, timestamp, fifo, undefined)
 160          */
 161         abstract protected function supportedOrders();
 162
 163         /**
 164          * Get the default queue order to use if configuration does not specify one
 165          *
 166          * @return string One of (random, timestamp, fifo, undefined)
 167          */
 168         abstract protected function optimalOrder();
 169
 170         /**
 171          * Find out if delayed jobs are supported for configuration validation
 172          *
 173          * @return bool Whether delayed jobs are supported
 174          */
 175         protected function supportsDelayedJobs() {
 176                 return false; // not implemented
 177         }
 178
 179         /**
 180          * @return bool Whether delayed jobs are enabled
 181          * @since 1.22
 182          */
 183         final public function delayedJobsEnabled() {
 184                 return $this->supportsDelayedJobs();
 185         }
 186
 187         /**
 188          * @return string|bool Read-only rational or false if r/w
 189          * @since 1.27
 190          */
 191         public function getReadOnlyReason() {
 192                 return $this->readOnlyReason;
 193         }
 194
 195         /**
 196          * Quickly check if the queue has no available (unacquired, non-delayed) jobs.
 197          * Queue classes should use caching if they are any slower without memcached.
 198          *
 199          * If caching is used, this might return false when there are actually no jobs.
 200          * If pop() is called and returns false then it should correct the cache. Also,
 201          * calling flushCaches() first prevents this. However, this affect is typically
 202          * not distinguishable from the race condition between isEmpty() and pop().
 203          *
 204          * @return bool
 205          * @throws JobQueueError
 206          */
 207         final public function isEmpty() {
 208                 $res = $this->doIsEmpty();
 209
 210                 return $res;
 211         }
 212
 213         /**
 214          * @see JobQueue::isEmpty()
 215          * @return bool
 216          */
 217         abstract protected function doIsEmpty();
 218
 219         /**
 220          * Get the number of available (unacquired, non-delayed) jobs in the queue.
 221          * Queue classes should use caching if they are any slower without memcached.
 222          *
 223          * If caching is used, this number might be out of date for a minute.
 224          *
 225          * @return int
 226          * @throws JobQueueError
 227          */
 228         final public function getSize() {
 229                 $res = $this->doGetSize();
 230
 231                 return $res;
 232         }
 233
 234         /**
 235          * @see JobQueue::getSize()
 236          * @return int
 237          */
 238         abstract protected function doGetSize();
 239
 240         /**
 241          * Get the number of acquired jobs (these are temporarily out of the queue).
 242          * Queue classes should use caching if they are any slower without memcached.
 243          *
 244          * If caching is used, this number might be out of date for a minute.
 245          *
 246          * @return int
 247          * @throws JobQueueError
 248          */
 249         final public function getAcquiredCount() {
 250                 $res = $this->doGetAcquiredCount();
 251
 252                 return $res;
 253         }
 254
 255         /**
 256          * @see JobQueue::getAcquiredCount()
 257          * @return int
 258          */
 259         abstract protected function doGetAcquiredCount();
 260
 261         /**
 262          * Get the number of delayed jobs (these are temporarily out of the queue).
 263          * Queue classes should use caching if they are any slower without memcached.
 264          *
 265          * If caching is used, this number might be out of date for a minute.
 266          *
 267          * @return int
 268          * @throws JobQueueError
 269          * @since 1.22
 270          */
 271         final public function getDelayedCount() {
 272                 $res = $this->doGetDelayedCount();
 273
 274                 return $res;
 275         }
 276
 277         /**
 278          * @see JobQueue::getDelayedCount()
 279          * @return int
 280          */
 281         protected function doGetDelayedCount() {
 282                 return 0; // not implemented
 283         }
 284
 285         /**
 286          * Get the number of acquired jobs that can no longer be attempted.
 287          * Queue classes should use caching if they are any slower without memcached.
 288          *
 289          * If caching is used, this number might be out of date for a minute.
 290          *
 291          * @return int
 292          * @throws JobQueueError
 293          */
 294         final public function getAbandonedCount() {
 295                 $res = $this->doGetAbandonedCount();
 296
 297                 return $res;
 298         }
 299
 300         /**
 301          * @see JobQueue::getAbandonedCount()
 302          * @return int
 303          */
 304         protected function doGetAbandonedCount() {
 305                 return 0; // not implemented
 306         }
 307
 308         /**
 309          * Push one or more jobs into the queue.
 310          * This does not require $wgJobClasses to be set for the given job type.
 311          * Outside callers should use JobQueueGroup::push() instead of this function.
 312          *
 313          * @param IJobSpecification|IJobSpecification[] $jobs
 314          * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
 315          * @return void
 316          * @throws JobQueueError
 317          */
 318         final public function push( $jobs, $flags = 0 ) {
 319                 $jobs = is_array( $jobs ) ? $jobs : [ $jobs ];
 320                 $this->batchPush( $jobs, $flags );
 321         }
 322
 323         /**
 324          * Push a batch of jobs into the queue.
 325          * This does not require $wgJobClasses to be set for the given job type.
 326          * Outside callers should use JobQueueGroup::push() instead of this function.
 327          *
 328          * @param IJobSpecification[] $jobs
 329          * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
 330          * @return void
 331          * @throws JobQueueError
 332          */
 333         final public function batchPush( array $jobs, $flags = 0 ) {
 334                 $this->assertNotReadOnly();
 335
 336                 if ( $jobs === [] ) {
 337                         return; // nothing to do
 338                 }
 339
 340                 foreach ( $jobs as $job ) {
 341                         if ( $job->getType() !== $this->type ) {
 342                                 throw new JobQueueError(
 343                                         "Got '{$job->getType()}' job; expected a '{$this->type}' job." );
 344                         } elseif ( $job->getReleaseTimestamp() && !$this->supportsDelayedJobs() ) {
 345                                 throw new JobQueueError(
 346                                         "Got delayed '{$job->getType()}' job; delays are not supported." );
 347                         }
 348                 }
 349
 350                 $this->doBatchPush( $jobs, $flags );
 351
 352                 foreach ( $jobs as $job ) {
 353                         if ( $job->isRootJob() ) {
 354                                 $this->deduplicateRootJob( $job );
 355                         }
 356                 }
 357         }
 358
 359         /**
 360          * @see JobQueue::batchPush()
 361          * @param IJobSpecification[] $jobs
 362          * @param int $flags
 363          */
 364         abstract protected function doBatchPush( array $jobs, $flags );
 365
 366         /**
 367          * Pop a job off of the queue.
 368          * This requires $wgJobClasses to be set for the given job type.
 369          * Outside callers should use JobQueueGroup::pop() instead of this function.
 370          *
 371          * @throws JobQueueError
 372          * @return RunnableJob|bool Returns false if there are no jobs
 373          */
 374         final public function pop() {
 375                 $this->assertNotReadOnly();
 376
 377                 $job = $this->doPop();
 378
 379                 // Flag this job as an old duplicate based on its "root" job...
 380                 try {
 381                         if ( $job && $this->isRootJobOldDuplicate( $job ) ) {
 382                                 $this->incrStats( 'dupe_pops', $this->type );
 383                                 $job = DuplicateJob::newFromJob( $job ); // convert to a no-op
 384                         }
 385                 } catch ( Exception $e ) {
 386                         // don't lose jobs over this
 387                 }
 388
 389                 return $job;
 390         }
 391
 392         /**
 393          * @see JobQueue::pop()
 394          * @return RunnableJob|bool
 395          */
 396         abstract protected function doPop();
 397
 398         /**
 399          * Acknowledge that a job was completed.
 400          *
 401          * This does nothing for certain queue classes or if "claimTTL" is not set.
 402          * Outside callers should use JobQueueGroup::ack() instead of this function.
 403          *
 404          * @param RunnableJob $job
 405          * @return void
 406          * @throws JobQueueError
 407          */
 408         final public function ack( RunnableJob $job ) {
 409                 $this->assertNotReadOnly();
 410                 if ( $job->getType() !== $this->type ) {
 411                         throw new JobQueueError( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 412                 }
 413
 414                 $this->doAck( $job );
 415         }
 416
 417         /**
 418          * @see JobQueue::ack()
 419          * @param RunnableJob $job
 420          */
 421         abstract protected function doAck( RunnableJob $job );
 422
 423         /**
 424          * Register the "root job" of a given job into the queue for de-duplication.
 425          * This should only be called right *after* all the new jobs have been inserted.
 426          * This is used to turn older, duplicate, job entries into no-ops. The root job
 427          * information will remain in the registry until it simply falls out of cache.
 428          *
 429          * This requires that $job has two special fields in the "params" array:
 430          *   - rootJobSignature : hash (e.g. SHA1) that identifies the task
 431          *   - rootJobTimestamp : TS_MW timestamp of this instance of the task
 432          *
 433          * A "root job" is a conceptual job that consist of potentially many smaller jobs
 434          * that are actually inserted into the queue. For example, "refreshLinks" jobs are
 435          * spawned when a template is edited. One can think of the task as "update links
 436          * of pages that use template X" and an instance of that task as a "root job".
 437          * However, what actually goes into the queue are range and leaf job subtypes.
 438          * Since these jobs include things like page ID ranges and DB master positions,
 439          * and can morph into smaller jobs recursively, simple duplicate detection
 440          * for individual jobs being identical (like that of job_sha1) is not useful.
 441          *
 442          * In the case of "refreshLinks", if these jobs are still in the queue when the template
 443          * is edited again, we want all of these old refreshLinks jobs for that template to become
 444          * no-ops. This can greatly reduce server load, since refreshLinks jobs involves parsing.
 445          * Essentially, the new batch of jobs belong to a new "root job" and the older ones to a
 446          * previous "root job" for the same task of "update links of pages that use template X".
 447          *
 448          * This does nothing for certain queue classes.
 449          *
 450          * @param IJobSpecification $job
 451          * @throws JobQueueError
 452          * @return bool
 453          */
 454         final public function deduplicateRootJob( IJobSpecification $job ) {
 455                 $this->assertNotReadOnly();
 456                 if ( $job->getType() !== $this->type ) {
 457                         throw new JobQueueError( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 458                 }
 459
 460                 return $this->doDeduplicateRootJob( $job );
 461         }
 462
 463         /**
 464          * @see JobQueue::deduplicateRootJob()
 465          * @param IJobSpecification $job
 466          * @throws JobQueueError
 467          * @return bool
 468          */
 469         protected function doDeduplicateRootJob( IJobSpecification $job ) {
 470                 $params = $job->hasRootJobParams() ? $job->getRootJobParams() : null;
 471                 if ( !$params ) {
 472                         throw new JobQueueError( "Cannot register root job; missing parameters." );
 473                 }
 474
 475                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 476                 // Callers should call JobQueueGroup::push() before this method so that if the
 477                 // insert fails, the de-duplication registration will be aborted. Having only the
 478                 // de-duplication registration succeed would cause jobs to become no-ops without
 479                 // any actual jobs that made them redundant.
 480                 $timestamp = $this->wanCache->get( $key ); // last known timestamp of such a root job
 481                 if ( $timestamp !== false && $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->wanCache->set( $key, $params['rootJobTimestamp'], self::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 IJobSpecification $job
 493          * @throws JobQueueError
 494          * @return bool
 495          */
 496         final protected function isRootJobOldDuplicate( IJobSpecification $job ) {
 497                 if ( $job->getType() !== $this->type ) {
 498                         throw new JobQueueError( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 499                 }
 500
 501                 return $this->doIsRootJobOldDuplicate( $job );
 502         }
 503
 504         /**
 505          * @see JobQueue::isRootJobOldDuplicate()
 506          * @param IJobSpecification $job
 507          * @return bool
 508          */
 509         protected function doIsRootJobOldDuplicate( IJobSpecification $job ) {
 510                 $params = $job->hasRootJobParams() ? $job->getRootJobParams() : null;
 511                 if ( !$params ) {
 512                         return false; // job has no de-deplication info
 513                 }
 514
 515                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 516                 // Get the last time this root job was enqueued
 517                 $timestamp = $this->wanCache->get( $key );
 518                 if ( $timestamp === false || $params['rootJobTimestamp'] > $timestamp ) {
 519                         // Update the timestamp of the last known root job started at the location...
 520                         $this->wanCache->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL );
 521                 }
 522
 523                 // Check if a new root job was started at the location after this one's...
 524                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 525         }
 526
 527         /**
 528          * @param string $signature Hash identifier of the root job
 529          * @return string
 530          */
 531         protected function getRootJobCacheKey( $signature ) {
 532                 return $this->wanCache->makeGlobalKey(
 533                         'jobqueue',
 534                         $this->domain,
 535                         $this->type,
 536                         'rootjob',
 537                         $signature
 538                 );
 539         }
 540
 541         /**
 542          * Deleted all unclaimed and delayed jobs from the queue
 543          *
 544          * @throws JobQueueError
 545          * @since 1.22
 546          * @return void
 547          */
 548         final public function delete() {
 549                 $this->assertNotReadOnly();
 550
 551                 $this->doDelete();
 552         }
 553
 554         /**
 555          * @see JobQueue::delete()
 556          * @throws JobQueueError
 557          */
 558         protected function doDelete() {
 559                 throw new JobQueueError( "This method is not implemented." );
 560         }
 561
 562         /**
 563          * Wait for any replica DBs or backup servers to catch up.
 564          *
 565          * This does nothing for certain queue classes.
 566          *
 567          * @return void
 568          * @throws JobQueueError
 569          */
 570         final public function waitForBackups() {
 571                 $this->doWaitForBackups();
 572         }
 573
 574         /**
 575          * @see JobQueue::waitForBackups()
 576          * @return void
 577          */
 578         protected function doWaitForBackups() {
 579         }
 580
 581         /**
 582          * Clear any process and persistent caches
 583          *
 584          * @return void
 585          */
 586         final public function flushCaches() {
 587                 $this->doFlushCaches();
 588         }
 589
 590         /**
 591          * @see JobQueue::flushCaches()
 592          * @return void
 593          */
 594         protected function doFlushCaches() {
 595         }
 596
 597         /**
 598          * Get an iterator to traverse over all available jobs in this queue.
 599          * This does not include jobs that are currently acquired or delayed.
 600          * Note: results may be stale if the queue is concurrently modified.
 601          *
 602          * @return Iterator
 603          * @throws JobQueueError
 604          */
 605         abstract public function getAllQueuedJobs();
 606
 607         /**
 608          * Get an iterator to traverse over all delayed jobs in this queue.
 609          * Note: results may be stale if the queue is concurrently modified.
 610          *
 611          * @return Iterator
 612          * @throws JobQueueError
 613          * @since 1.22
 614          */
 615         public function getAllDelayedJobs() {
 616                 return new ArrayIterator( [] ); // not implemented
 617         }
 618
 619         /**
 620          * Get an iterator to traverse over all claimed jobs in this queue
 621          *
 622          * Callers should be quick to iterator over it or few results
 623          * will be returned due to jobs being acknowledged and deleted
 624          *
 625          * @return Iterator
 626          * @throws JobQueueError
 627          * @since 1.26
 628          */
 629         public function getAllAcquiredJobs() {
 630                 return new ArrayIterator( [] ); // not implemented
 631         }
 632
 633         /**
 634          * Get an iterator to traverse over all abandoned jobs in this queue
 635          *
 636          * @return Iterator
 637          * @throws JobQueueError
 638          * @since 1.25
 639          */
 640         public function getAllAbandonedJobs() {
 641                 return new ArrayIterator( [] ); // not implemented
 642         }
 643
 644         /**
 645          * Do not use this function outside of JobQueue/JobQueueGroup
 646          *
 647          * @return string
 648          * @since 1.22
 649          */
 650         public function getCoalesceLocationInternal() {
 651                 return null;
 652         }
 653
 654         /**
 655          * Check whether each of the given queues are empty.
 656          * This is used for batching checks for queues stored at the same place.
 657          *
 658          * @param array $types List of queues types
 659          * @return array|null (list of non-empty queue types) or null if unsupported
 660          * @throws JobQueueError
 661          * @since 1.22
 662          */
 663         final public function getSiblingQueuesWithJobs( array $types ) {
 664                 return $this->doGetSiblingQueuesWithJobs( $types );
 665         }
 666
 667         /**
 668          * @see JobQueue::getSiblingQueuesWithJobs()
 669          * @param array $types List of queues types
 670          * @return array|null (list of queue types) or null if unsupported
 671          */
 672         protected function doGetSiblingQueuesWithJobs( array $types ) {
 673                 return null; // not supported
 674         }
 675
 676         /**
 677          * Check the size of each of the given queues.
 678          * For queues not served by the same store as this one, 0 is returned.
 679          * This is used for batching checks for queues stored at the same place.
 680          *
 681          * @param array $types List of queues types
 682          * @return array|null (job type => whether queue is empty) or null if unsupported
 683          * @throws JobQueueError
 684          * @since 1.22
 685          */
 686         final public function getSiblingQueueSizes( array $types ) {
 687                 return $this->doGetSiblingQueueSizes( $types );
 688         }
 689
 690         /**
 691          * @see JobQueue::getSiblingQueuesSize()
 692          * @param array $types List of queues types
 693          * @return array|null (list of queue types) or null if unsupported
 694          */
 695         protected function doGetSiblingQueueSizes( array $types ) {
 696                 return null; // not supported
 697         }
 698
 699         /**
 700          * @param string $command
 701          * @param array $params
 702          * @return Job
 703          */
 704         protected function factoryJob( $command, $params ) {
 705                 // @TODO: dependency inject this as a callback
 706                 return Job::factory( $command, $params );
 707         }
 708
 709         /**
 710          * @throws JobQueueReadOnlyError
 711          */
 712         protected function assertNotReadOnly() {
 713                 if ( $this->readOnlyReason !== false ) {
 714                         throw new JobQueueReadOnlyError( "Job queue is read-only: {$this->readOnlyReason}" );
 715                 }
 716         }
 717
 718         /**
 719          * Call wfIncrStats() for the queue overall and for the queue type
 720          *
 721          * @param string $key Event type
 722          * @param string $type Job type
 723          * @param int $delta
 724          * @since 1.22
 725          */
 726         protected function incrStats( $key, $type, $delta = 1 ) {
 727                 $this->stats->updateCount( "jobqueue.{$key}.all", $delta );
 728                 $this->stats->updateCount( "jobqueue.{$key}.{$type}", $delta );
 729         }
 730 }