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7 * the Free Software Foundation; either version 2 of the License, or
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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
21 * @defgroup JobQueue JobQueue
23 use Liuggio\StatsdClient\Factory\StatsdDataFactoryInterface
;
26 * Class to handle enqueueing and running of background jobs
31 abstract class JobQueue
{
32 /** @var string DB domain ID */
34 /** @var string Job type */
36 /** @var string Job priority for pop() */
38 /** @var int Time to live in seconds */
40 /** @var int Maximum number of times to try a job */
42 /** @var string|bool Read only rationale (or false if r/w) */
43 protected $readOnlyReason;
44 /** @var StatsdDataFactoryInterface */
50 const QOS_ATOMIC
= 1; // integer; "all-or-nothing" job insertions
52 const ROOTJOB_TTL
= 2419200; // integer; seconds to remember root jobs (28 days)
55 * @param array $params
56 * @throws JobQueueError
58 protected function __construct( array $params ) {
59 $this->domain
= $params['domain'] ??
$params['wiki']; // b/c
60 $this->type
= $params['type'];
61 $this->claimTTL
= $params['claimTTL'] ??
0;
62 $this->maxTries
= $params['maxTries'] ??
3;
63 if ( isset( $params['order'] ) && $params['order'] !== 'any' ) {
64 $this->order
= $params['order'];
66 $this->order
= $this->optimalOrder();
68 if ( !in_array( $this->order
, $this->supportedOrders() ) ) {
69 throw new JobQueueError( __CLASS__
. " does not support '{$this->order}' order." );
71 $this->readOnlyReason
= $params['readOnlyReason'] ??
false;
72 $this->stats
= $params['stats'] ??
new NullStatsdDataFactory();
73 $this->dupCache
= $params['stash'] ??
new EmptyBagOStuff();
77 * Get a job queue object of the specified type.
79 * - class : What job class to use (determines job type)
80 * - domain : Database domain ID of the wiki the jobs are for (defaults to current wiki)
81 * - type : The name of the job types this queue handles
82 * - order : Order that pop() selects jobs, one of "fifo", "timestamp" or "random".
83 * If "fifo" is used, the queue will effectively be FIFO. Note that job
84 * completion will not appear to be exactly FIFO if there are multiple
85 * job runners since jobs can take different times to finish once popped.
86 * If "timestamp" is used, the queue will at least be loosely ordered
87 * by timestamp, allowing for some jobs to be popped off out of order.
88 * If "random" is used, pop() will pick jobs in random order.
89 * Note that it may only be weakly random (e.g. a lottery of the oldest X).
90 * If "any" is choosen, the queue will use whatever order is the fastest.
91 * This might be useful for improving concurrency for job acquisition.
92 * - claimTTL : If supported, the queue will recycle jobs that have been popped
93 * but not acknowledged as completed after this many seconds. Recycling
94 * of jobs simply means re-inserting them into the queue. Jobs can be
95 * attempted up to three times before being discarded.
96 * - readOnlyReason : Set this to a string to make the queue read-only.
97 * - stash : A BagOStuff instance that can be used for root job deduplication
98 * - stats : A StatsdDataFactoryInterface [optional]
100 * Queue classes should throw an exception if they do not support the options given.
102 * @param array $params
104 * @throws JobQueueError
106 final public static function factory( array $params ) {
107 $class = $params['class'];
108 if ( !class_exists( $class ) ) {
109 throw new JobQueueError( "Invalid job queue class '$class'." );
111 $obj = new $class( $params );
112 if ( !( $obj instanceof self
) ) {
113 throw new JobQueueError( "Class '$class' is not a " . __CLASS__
. " class." );
120 * @return string Database domain ID
122 final public function getDomain() {
123 return $this->domain
;
127 * @return string Wiki ID
130 final public function getWiki() {
131 return WikiMap
::getWikiIdFromDbDomain( $this->domain
);
135 * @return string Job type that this queue handles
137 final public function getType() {
142 * @return string One of (random, timestamp, fifo, undefined)
144 final public function getOrder() {
149 * Get the allowed queue orders for configuration validation
151 * @return array Subset of (random, timestamp, fifo, undefined)
153 abstract protected function supportedOrders();
156 * Get the default queue order to use if configuration does not specify one
158 * @return string One of (random, timestamp, fifo, undefined)
160 abstract protected function optimalOrder();
163 * Find out if delayed jobs are supported for configuration validation
165 * @return bool Whether delayed jobs are supported
167 protected function supportsDelayedJobs() {
168 return false; // not implemented
172 * @return bool Whether delayed jobs are enabled
175 final public function delayedJobsEnabled() {
176 return $this->supportsDelayedJobs();
180 * @return string|bool Read-only rational or false if r/w
183 public function getReadOnlyReason() {
184 return $this->readOnlyReason
;
188 * Quickly check if the queue has no available (unacquired, non-delayed) jobs.
189 * Queue classes should use caching if they are any slower without memcached.
191 * If caching is used, this might return false when there are actually no jobs.
192 * If pop() is called and returns false then it should correct the cache. Also,
193 * calling flushCaches() first prevents this. However, this affect is typically
194 * not distinguishable from the race condition between isEmpty() and pop().
197 * @throws JobQueueError
199 final public function isEmpty() {
200 $res = $this->doIsEmpty();
206 * @see JobQueue::isEmpty()
209 abstract protected function doIsEmpty();
212 * Get the number of available (unacquired, non-delayed) jobs in the queue.
213 * Queue classes should use caching if they are any slower without memcached.
215 * If caching is used, this number might be out of date for a minute.
218 * @throws JobQueueError
220 final public function getSize() {
221 $res = $this->doGetSize();
227 * @see JobQueue::getSize()
230 abstract protected function doGetSize();
233 * Get the number of acquired jobs (these are temporarily out of the queue).
234 * Queue classes should use caching if they are any slower without memcached.
236 * If caching is used, this number might be out of date for a minute.
239 * @throws JobQueueError
241 final public function getAcquiredCount() {
242 $res = $this->doGetAcquiredCount();
248 * @see JobQueue::getAcquiredCount()
251 abstract protected function doGetAcquiredCount();
254 * Get the number of delayed jobs (these are temporarily out of the queue).
255 * Queue classes should use caching if they are any slower without memcached.
257 * If caching is used, this number might be out of date for a minute.
260 * @throws JobQueueError
263 final public function getDelayedCount() {
264 $res = $this->doGetDelayedCount();
270 * @see JobQueue::getDelayedCount()
273 protected function doGetDelayedCount() {
274 return 0; // not implemented
278 * Get the number of acquired jobs that can no longer be attempted.
279 * Queue classes should use caching if they are any slower without memcached.
281 * If caching is used, this number might be out of date for a minute.
284 * @throws JobQueueError
286 final public function getAbandonedCount() {
287 $res = $this->doGetAbandonedCount();
293 * @see JobQueue::getAbandonedCount()
296 protected function doGetAbandonedCount() {
297 return 0; // not implemented
301 * Push one or more jobs into the queue.
302 * This does not require $wgJobClasses to be set for the given job type.
303 * Outside callers should use JobQueueGroup::push() instead of this function.
305 * @param IJobSpecification|IJobSpecification[] $jobs
306 * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
308 * @throws JobQueueError
310 final public function push( $jobs, $flags = 0 ) {
311 $jobs = is_array( $jobs ) ?
$jobs : [ $jobs ];
312 $this->batchPush( $jobs, $flags );
316 * Push a batch of jobs into the queue.
317 * This does not require $wgJobClasses to be set for the given job type.
318 * Outside callers should use JobQueueGroup::push() instead of this function.
320 * @param IJobSpecification[] $jobs
321 * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
323 * @throws JobQueueError
325 final public function batchPush( array $jobs, $flags = 0 ) {
326 $this->assertNotReadOnly();
328 if ( $jobs === [] ) {
329 return; // nothing to do
332 foreach ( $jobs as $job ) {
333 if ( $job->getType() !== $this->type
) {
334 throw new JobQueueError(
335 "Got '{$job->getType()}' job; expected a '{$this->type}' job." );
336 } elseif ( $job->getReleaseTimestamp() && !$this->supportsDelayedJobs() ) {
337 throw new JobQueueError(
338 "Got delayed '{$job->getType()}' job; delays are not supported." );
342 $this->doBatchPush( $jobs, $flags );
344 foreach ( $jobs as $job ) {
345 if ( $job->isRootJob() ) {
346 $this->deduplicateRootJob( $job );
352 * @see JobQueue::batchPush()
353 * @param IJobSpecification[] $jobs
356 abstract protected function doBatchPush( array $jobs, $flags );
359 * Pop a job off of the queue.
360 * This requires $wgJobClasses to be set for the given job type.
361 * Outside callers should use JobQueueGroup::pop() instead of this function.
363 * @throws JobQueueError
364 * @return RunnableJob|bool Returns false if there are no jobs
366 final public function pop() {
367 $this->assertNotReadOnly();
369 $job = $this->doPop();
371 // Flag this job as an old duplicate based on its "root" job...
373 if ( $job && $this->isRootJobOldDuplicate( $job ) ) {
374 $this->incrStats( 'dupe_pops', $this->type
);
375 $job = DuplicateJob
::newFromJob( $job ); // convert to a no-op
377 } catch ( Exception
$e ) {
378 // don't lose jobs over this
385 * @see JobQueue::pop()
386 * @return RunnableJob|bool
388 abstract protected function doPop();
391 * Acknowledge that a job was completed.
393 * This does nothing for certain queue classes or if "claimTTL" is not set.
394 * Outside callers should use JobQueueGroup::ack() instead of this function.
396 * @param RunnableJob $job
398 * @throws JobQueueError
400 final public function ack( RunnableJob
$job ) {
401 $this->assertNotReadOnly();
402 if ( $job->getType() !== $this->type
) {
403 throw new JobQueueError( "Got '{$job->getType()}' job; expected '{$this->type}'." );
406 $this->doAck( $job );
410 * @see JobQueue::ack()
411 * @param RunnableJob $job
413 abstract protected function doAck( RunnableJob
$job );
416 * Register the "root job" of a given job into the queue for de-duplication.
417 * This should only be called right *after* all the new jobs have been inserted.
418 * This is used to turn older, duplicate, job entries into no-ops. The root job
419 * information will remain in the registry until it simply falls out of cache.
421 * This requires that $job has two special fields in the "params" array:
422 * - rootJobSignature : hash (e.g. SHA1) that identifies the task
423 * - rootJobTimestamp : TS_MW timestamp of this instance of the task
425 * A "root job" is a conceptual job that consist of potentially many smaller jobs
426 * that are actually inserted into the queue. For example, "refreshLinks" jobs are
427 * spawned when a template is edited. One can think of the task as "update links
428 * of pages that use template X" and an instance of that task as a "root job".
429 * However, what actually goes into the queue are range and leaf job subtypes.
430 * Since these jobs include things like page ID ranges and DB master positions,
431 * and can morph into smaller jobs recursively, simple duplicate detection
432 * for individual jobs being identical (like that of job_sha1) is not useful.
434 * In the case of "refreshLinks", if these jobs are still in the queue when the template
435 * is edited again, we want all of these old refreshLinks jobs for that template to become
436 * no-ops. This can greatly reduce server load, since refreshLinks jobs involves parsing.
437 * Essentially, the new batch of jobs belong to a new "root job" and the older ones to a
438 * previous "root job" for the same task of "update links of pages that use template X".
440 * This does nothing for certain queue classes.
442 * @param IJobSpecification $job
443 * @throws JobQueueError
446 final public function deduplicateRootJob( IJobSpecification
$job ) {
447 $this->assertNotReadOnly();
448 if ( $job->getType() !== $this->type
) {
449 throw new JobQueueError( "Got '{$job->getType()}' job; expected '{$this->type}'." );
452 return $this->doDeduplicateRootJob( $job );
456 * @see JobQueue::deduplicateRootJob()
457 * @param IJobSpecification $job
458 * @throws JobQueueError
461 protected function doDeduplicateRootJob( IJobSpecification
$job ) {
462 if ( !$job->hasRootJobParams() ) {
463 throw new JobQueueError( "Cannot register root job; missing parameters." );
465 $params = $job->getRootJobParams();
467 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
468 // Callers should call JobQueueGroup::push() before this method so that if the insert
469 // fails, the de-duplication registration will be aborted. Since the insert is
470 // deferred till "transaction idle", do the same here, so that the ordering is
471 // maintained. Having only the de-duplication registration succeed would cause
472 // jobs to become no-ops without any actual jobs that made them redundant.
473 $timestamp = $this->dupCache
->get( $key ); // current last timestamp of this job
474 if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
475 return true; // a newer version of this root job was enqueued
478 // Update the timestamp of the last root job started at the location...
479 return $this->dupCache
->set( $key, $params['rootJobTimestamp'], self
::ROOTJOB_TTL
);
483 * Check if the "root" job of a given job has been superseded by a newer one
485 * @param IJobSpecification $job
486 * @throws JobQueueError
489 final protected function isRootJobOldDuplicate( IJobSpecification
$job ) {
490 if ( $job->getType() !== $this->type
) {
491 throw new JobQueueError( "Got '{$job->getType()}' job; expected '{$this->type}'." );
493 $isDuplicate = $this->doIsRootJobOldDuplicate( $job );
499 * @see JobQueue::isRootJobOldDuplicate()
500 * @param IJobSpecification $job
503 protected function doIsRootJobOldDuplicate( IJobSpecification
$job ) {
504 if ( !$job->hasRootJobParams() ) {
505 return false; // job has no de-deplication info
507 $params = $job->getRootJobParams();
509 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
510 // Get the last time this root job was enqueued
511 $timestamp = $this->dupCache
->get( $key );
513 // Check if a new root job was started at the location after this one's...
514 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
518 * @param string $signature Hash identifier of the root job
521 protected function getRootJobCacheKey( $signature ) {
522 return $this->dupCache
->makeGlobalKey(
532 * Deleted all unclaimed and delayed jobs from the queue
534 * @throws JobQueueError
538 final public function delete() {
539 $this->assertNotReadOnly();
545 * @see JobQueue::delete()
546 * @throws JobQueueError
548 protected function doDelete() {
549 throw new JobQueueError( "This method is not implemented." );
553 * Wait for any replica DBs or backup servers to catch up.
555 * This does nothing for certain queue classes.
558 * @throws JobQueueError
560 final public function waitForBackups() {
561 $this->doWaitForBackups();
565 * @see JobQueue::waitForBackups()
568 protected function doWaitForBackups() {
572 * Clear any process and persistent caches
576 final public function flushCaches() {
577 $this->doFlushCaches();
581 * @see JobQueue::flushCaches()
584 protected function doFlushCaches() {
588 * Get an iterator to traverse over all available jobs in this queue.
589 * This does not include jobs that are currently acquired or delayed.
590 * Note: results may be stale if the queue is concurrently modified.
593 * @throws JobQueueError
595 abstract public function getAllQueuedJobs();
598 * Get an iterator to traverse over all delayed jobs in this queue.
599 * Note: results may be stale if the queue is concurrently modified.
602 * @throws JobQueueError
605 public function getAllDelayedJobs() {
606 return new ArrayIterator( [] ); // not implemented
610 * Get an iterator to traverse over all claimed jobs in this queue
612 * Callers should be quick to iterator over it or few results
613 * will be returned due to jobs being acknowledged and deleted
616 * @throws JobQueueError
619 public function getAllAcquiredJobs() {
620 return new ArrayIterator( [] ); // not implemented
624 * Get an iterator to traverse over all abandoned jobs in this queue
627 * @throws JobQueueError
630 public function getAllAbandonedJobs() {
631 return new ArrayIterator( [] ); // not implemented
635 * Do not use this function outside of JobQueue/JobQueueGroup
640 public function getCoalesceLocationInternal() {
645 * Check whether each of the given queues are empty.
646 * This is used for batching checks for queues stored at the same place.
648 * @param array $types List of queues types
649 * @return array|null (list of non-empty queue types) or null if unsupported
650 * @throws JobQueueError
653 final public function getSiblingQueuesWithJobs( array $types ) {
654 return $this->doGetSiblingQueuesWithJobs( $types );
658 * @see JobQueue::getSiblingQueuesWithJobs()
659 * @param array $types List of queues types
660 * @return array|null (list of queue types) or null if unsupported
662 protected function doGetSiblingQueuesWithJobs( array $types ) {
663 return null; // not supported
667 * Check the size of each of the given queues.
668 * For queues not served by the same store as this one, 0 is returned.
669 * This is used for batching checks for queues stored at the same place.
671 * @param array $types List of queues types
672 * @return array|null (job type => whether queue is empty) or null if unsupported
673 * @throws JobQueueError
676 final public function getSiblingQueueSizes( array $types ) {
677 return $this->doGetSiblingQueueSizes( $types );
681 * @see JobQueue::getSiblingQueuesSize()
682 * @param array $types List of queues types
683 * @return array|null (list of queue types) or null if unsupported
685 protected function doGetSiblingQueueSizes( array $types ) {
686 return null; // not supported
690 * @param string $command
691 * @param array $params
694 protected function factoryJob( $command, $params ) {
695 // @TODO: dependency inject this as a callback
696 return Job
::factory( $command, $params );
700 * @throws JobQueueReadOnlyError
702 protected function assertNotReadOnly() {
703 if ( $this->readOnlyReason
!== false ) {
704 throw new JobQueueReadOnlyError( "Job queue is read-only: {$this->readOnlyReason}" );
709 * Call wfIncrStats() for the queue overall and for the queue type
711 * @param string $key Event type
712 * @param string $type Job type
716 protected function incrStats( $key, $type, $delta = 1 ) {
717 $this->stats
->updateCount( "jobqueue.{$key}.all", $delta );
718 $this->stats
->updateCount( "jobqueue.{$key}.{$type}", $delta );