Move Blob class to Rdbms namespaces
[mediawiki.git] / includes / jobqueue / JobQueue.php
blob020a68472852ee46c35448f1c30d529be1a04ddc
1 <?php
2 /**
3 * Job queue base code.
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.
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.
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
20 * @file
21 * @defgroup JobQueue JobQueue
22 * @author Aaron Schulz
25 /**
26 * Class to handle enqueueing and running of background jobs
28 * @ingroup JobQueue
29 * @since 1.21
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;
45 /** @var BagOStuff */
46 protected $dupCache;
47 /** @var JobQueueAggregator */
48 protected $aggr;
50 const QOS_ATOMIC = 1; // integer; "all-or-nothing" job insertions
52 const ROOTJOB_TTL = 2419200; // integer; seconds to remember root jobs (28 days)
54 /**
55 * @param array $params
56 * @throws MWException
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();
68 if ( !in_array( $this->order, $this->supportedOrders() ) ) {
69 throw new MWException( __CLASS__ . " does not support '{$this->order}' order." );
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;
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.
102 * Queue classes should throw an exception if they do not support the options given.
104 * @param array $params
105 * @return JobQueue
106 * @throws MWException
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'." );
113 $obj = new $class( $params );
114 if ( !( $obj instanceof self ) ) {
115 throw new MWException( "Class '$class' is not a " . __CLASS__ . " class." );
118 return $obj;
122 * @return string Wiki ID
124 final public function getWiki() {
125 return $this->wiki;
129 * @return string Job type that this queue handles
131 final public function getType() {
132 return $this->type;
136 * @return string One of (random, timestamp, fifo, undefined)
138 final public function getOrder() {
139 return $this->order;
143 * Get the allowed queue orders for configuration validation
145 * @return array Subset of (random, timestamp, fifo, undefined)
147 abstract protected function supportedOrders();
150 * Get the default queue order to use if configuration does not specify one
152 * @return string One of (random, timestamp, fifo, undefined)
154 abstract protected function optimalOrder();
157 * Find out if delayed jobs are supported for configuration validation
159 * @return bool Whether delayed jobs are supported
161 protected function supportsDelayedJobs() {
162 return false; // not implemented
166 * @return bool Whether delayed jobs are enabled
167 * @since 1.22
169 final public function delayedJobsEnabled() {
170 return $this->supportsDelayedJobs();
174 * @return string|bool Read-only rational or false if r/w
175 * @since 1.27
177 public function getReadOnlyReason() {
178 return $this->readOnlyReason;
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.
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().
190 * @return bool
191 * @throws JobQueueError
193 final public function isEmpty() {
194 $res = $this->doIsEmpty();
196 return $res;
200 * @see JobQueue::isEmpty()
201 * @return bool
203 abstract protected function doIsEmpty();
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.
209 * If caching is used, this number might be out of date for a minute.
211 * @return int
212 * @throws JobQueueError
214 final public function getSize() {
215 $res = $this->doGetSize();
217 return $res;
221 * @see JobQueue::getSize()
222 * @return int
224 abstract protected function doGetSize();
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.
230 * If caching is used, this number might be out of date for a minute.
232 * @return int
233 * @throws JobQueueError
235 final public function getAcquiredCount() {
236 $res = $this->doGetAcquiredCount();
238 return $res;
242 * @see JobQueue::getAcquiredCount()
243 * @return int
245 abstract protected function doGetAcquiredCount();
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.
251 * If caching is used, this number might be out of date for a minute.
253 * @return int
254 * @throws JobQueueError
255 * @since 1.22
257 final public function getDelayedCount() {
258 $res = $this->doGetDelayedCount();
260 return $res;
264 * @see JobQueue::getDelayedCount()
265 * @return int
267 protected function doGetDelayedCount() {
268 return 0; // not implemented
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.
275 * If caching is used, this number might be out of date for a minute.
277 * @return int
278 * @throws JobQueueError
280 final public function getAbandonedCount() {
281 $res = $this->doGetAbandonedCount();
283 return $res;
287 * @see JobQueue::getAbandonedCount()
288 * @return int
290 protected function doGetAbandonedCount() {
291 return 0; // not implemented
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.
299 * @param IJobSpecification|IJobSpecification[] $jobs
300 * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
301 * @return void
302 * @throws JobQueueError
304 final public function push( $jobs, $flags = 0 ) {
305 $jobs = is_array( $jobs ) ? $jobs : [ $jobs ];
306 $this->batchPush( $jobs, $flags );
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.
314 * @param IJobSpecification[] $jobs
315 * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
316 * @return void
317 * @throws MWException
319 final public function batchPush( array $jobs, $flags = 0 ) {
320 $this->assertNotReadOnly();
322 if ( !count( $jobs ) ) {
323 return; // nothing to do
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." );
336 $this->doBatchPush( $jobs, $flags );
337 $this->aggr->notifyQueueNonEmpty( $this->wiki, $this->type );
339 foreach ( $jobs as $job ) {
340 if ( $job->isRootJob() ) {
341 $this->deduplicateRootJob( $job );
347 * @see JobQueue::batchPush()
348 * @param IJobSpecification[] $jobs
349 * @param int $flags
351 abstract protected function doBatchPush( array $jobs, $flags );
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.
358 * @throws MWException
359 * @return Job|bool Returns false if there are no jobs
361 final public function pop() {
362 global $wgJobClasses;
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}'." );
372 $job = $this->doPop();
374 if ( !$job ) {
375 $this->aggr->notifyQueueEmpty( $this->wiki, $this->type );
378 // Flag this job as an old duplicate based on its "root" job...
379 try {
380 if ( $job && $this->isRootJobOldDuplicate( $job ) ) {
381 JobQueue::incrStats( 'dupe_pops', $this->type );
382 $job = DuplicateJob::newFromJob( $job ); // convert to a no-op
384 } catch ( Exception $e ) {
385 // don't lose jobs over this
388 return $job;
392 * @see JobQueue::pop()
393 * @return Job|bool
395 abstract protected function doPop();
398 * Acknowledge that a job was completed.
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.
403 * @param Job $job
404 * @return void
405 * @throws MWException
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}'." );
413 $this->doAck( $job );
417 * @see JobQueue::ack()
418 * @param Job $job
420 abstract protected function doAck( Job $job );
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.
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
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.
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".
447 * This does nothing for certain queue classes.
449 * @param IJobSpecification $job
450 * @throws MWException
451 * @return bool
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}'." );
459 return $this->doDeduplicateRootJob( $job );
463 * @see JobQueue::deduplicateRootJob()
464 * @param IJobSpecification $job
465 * @throws MWException
466 * @return bool
468 protected function doDeduplicateRootJob( IJobSpecification $job ) {
469 if ( !$job->hasRootJobParams() ) {
470 throw new MWException( "Cannot register root job; missing parameters." );
472 $params = $job->getRootJobParams();
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
485 // Update the timestamp of the last root job started at the location...
486 return $this->dupCache->set( $key, $params['rootJobTimestamp'], JobQueueDB::ROOTJOB_TTL );
490 * Check if the "root" job of a given job has been superseded by a newer one
492 * @param Job $job
493 * @throws MWException
494 * @return bool
496 final protected function isRootJobOldDuplicate( Job $job ) {
497 if ( $job->getType() !== $this->type ) {
498 throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
500 $isDuplicate = $this->doIsRootJobOldDuplicate( $job );
502 return $isDuplicate;
506 * @see JobQueue::isRootJobOldDuplicate()
507 * @param Job $job
508 * @return bool
510 protected function doIsRootJobOldDuplicate( Job $job ) {
511 if ( !$job->hasRootJobParams() ) {
512 return false; // job has no de-deplication info
514 $params = $job->getRootJobParams();
516 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
517 // Get the last time this root job was enqueued
518 $timestamp = $this->dupCache->get( $key );
520 // Check if a new root job was started at the location after this one's...
521 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
525 * @param string $signature Hash identifier of the root job
526 * @return string
528 protected function getRootJobCacheKey( $signature ) {
529 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
531 return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, 'rootjob', $signature );
535 * Deleted all unclaimed and delayed jobs from the queue
537 * @throws JobQueueError
538 * @since 1.22
539 * @return void
541 final public function delete() {
542 $this->assertNotReadOnly();
544 $this->doDelete();
548 * @see JobQueue::delete()
549 * @throws MWException
551 protected function doDelete() {
552 throw new MWException( "This method is not implemented." );
556 * Wait for any replica DBs or backup servers to catch up.
558 * This does nothing for certain queue classes.
560 * @return void
561 * @throws JobQueueError
563 final public function waitForBackups() {
564 $this->doWaitForBackups();
568 * @see JobQueue::waitForBackups()
569 * @return void
571 protected function doWaitForBackups() {
575 * Clear any process and persistent caches
577 * @return void
579 final public function flushCaches() {
580 $this->doFlushCaches();
584 * @see JobQueue::flushCaches()
585 * @return void
587 protected function doFlushCaches() {
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.
595 * @return Iterator
596 * @throws JobQueueError
598 abstract public function getAllQueuedJobs();
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.
604 * @return Iterator
605 * @throws JobQueueError
606 * @since 1.22
608 public function getAllDelayedJobs() {
609 return new ArrayIterator( [] ); // not implemented
613 * Get an iterator to traverse over all claimed jobs in this queue
615 * Callers should be quick to iterator over it or few results
616 * will be returned due to jobs being acknowledged and deleted
618 * @return Iterator
619 * @throws JobQueueError
620 * @since 1.26
622 public function getAllAcquiredJobs() {
623 return new ArrayIterator( [] ); // not implemented
627 * Get an iterator to traverse over all abandoned jobs in this queue
629 * @return Iterator
630 * @throws JobQueueError
631 * @since 1.25
633 public function getAllAbandonedJobs() {
634 return new ArrayIterator( [] ); // not implemented
638 * Do not use this function outside of JobQueue/JobQueueGroup
640 * @return string
641 * @since 1.22
643 public function getCoalesceLocationInternal() {
644 return null;
648 * Check whether each of the given queues are empty.
649 * This is used for batching checks for queues stored at the same place.
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
656 final public function getSiblingQueuesWithJobs( array $types ) {
657 return $this->doGetSiblingQueuesWithJobs( $types );
661 * @see JobQueue::getSiblingQueuesWithJobs()
662 * @param array $types List of queues types
663 * @return array|null (list of queue types) or null if unsupported
665 protected function doGetSiblingQueuesWithJobs( array $types ) {
666 return null; // not supported
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.
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
679 final public function getSiblingQueueSizes( array $types ) {
680 return $this->doGetSiblingQueueSizes( $types );
684 * @see JobQueue::getSiblingQueuesSize()
685 * @param array $types List of queues types
686 * @return array|null (list of queue types) or null if unsupported
688 protected function doGetSiblingQueueSizes( array $types ) {
689 return null; // not supported
693 * @throws JobQueueReadOnlyError
695 protected function assertNotReadOnly() {
696 if ( $this->readOnlyReason !== false ) {
697 throw new JobQueueReadOnlyError( "Job queue is read-only: {$this->readOnlyReason}" );
702 * Call wfIncrStats() for the queue overall and for the queue type
704 * @param string $key Event type
705 * @param string $type Job type
706 * @param int $delta
707 * @since 1.22
709 public static function incrStats( $key, $type, $delta = 1 ) {
710 static $stats;
711 if ( !$stats ) {
712 $stats = RequestContext::getMain()->getStats();
714 $stats->updateCount( "jobqueue.{$key}.all", $delta );
715 $stats->updateCount( "jobqueue.{$key}.{$type}", $delta );
720 * @ingroup JobQueue
721 * @since 1.22
723 class JobQueueError extends MWException {
726 class JobQueueConnectionError extends JobQueueError {
729 class JobQueueReadOnlyError extends JobQueueError {