wiki = $params['wiki']; $this->type = $params['type']; $this->claimTTL = isset( $params['claimTTL'] ) ? $params['claimTTL'] : 0; $this->maxTries = isset( $params['maxTries'] ) ? $params['maxTries'] : 3; if ( isset( $params['order'] ) && $params['order'] !== 'any' ) { $this->order = $params['order']; } else { $this->order = $this->optimalOrder(); } if ( !in_array( $this->order, $this->supportedOrders() ) ) { throw new MWException( __CLASS__ . " does not support '{$this->order}' order." ); } $this->dupCache = wfGetCache( CACHE_ANYTHING ); $this->aggr = isset( $params['aggregator'] ) ? $params['aggregator'] : new JobQueueAggregatorNull( [] ); $this->readOnlyReason = isset( $params['readOnlyReason'] ) ? $params['readOnlyReason'] : false; } /** * Get a job queue object of the specified type. * $params includes: * - class : What job class to use (determines job type) * - wiki : wiki ID of the wiki the jobs are for (defaults to current wiki) * - type : The name of the job types this queue handles * - order : Order that pop() selects jobs, one of "fifo", "timestamp" or "random". * If "fifo" is used, the queue will effectively be FIFO. Note that job * completion will not appear to be exactly FIFO if there are multiple * job runners since jobs can take different times to finish once popped. * If "timestamp" is used, the queue will at least be loosely ordered * by timestamp, allowing for some jobs to be popped off out of order. * If "random" is used, pop() will pick jobs in random order. * Note that it may only be weakly random (e.g. a lottery of the oldest X). * If "any" is choosen, the queue will use whatever order is the fastest. * This might be useful for improving concurrency for job acquisition. * - claimTTL : If supported, the queue will recycle jobs that have been popped * but not acknowledged as completed after this many seconds. Recycling * of jobs simply means re-inserting them into the queue. Jobs can be * attempted up to three times before being discarded. * - readOnlyReason : Set this to a string to make the queue read-only. * * Queue classes should throw an exception if they do not support the options given. * * @param array $params * @return JobQueue * @throws MWException */ final public static function factory( array $params ) { $class = $params['class']; if ( !class_exists( $class ) ) { throw new MWException( "Invalid job queue class '$class'." ); } $obj = new $class( $params ); if ( !( $obj instanceof self ) ) { throw new MWException( "Class '$class' is not a " . __CLASS__ . " class." ); } return $obj; } /** * @return string Wiki ID */ final public function getWiki() { return $this->wiki; } /** * @return string Job type that this queue handles */ final public function getType() { return $this->type; } /** * @return string One of (random, timestamp, fifo, undefined) */ final public function getOrder() { return $this->order; } /** * Get the allowed queue orders for configuration validation * * @return array Subset of (random, timestamp, fifo, undefined) */ abstract protected function supportedOrders(); /** * Get the default queue order to use if configuration does not specify one * * @return string One of (random, timestamp, fifo, undefined) */ abstract protected function optimalOrder(); /** * Find out if delayed jobs are supported for configuration validation * * @return bool Whether delayed jobs are supported */ protected function supportsDelayedJobs() { return false; // not implemented } /** * @return bool Whether delayed jobs are enabled * @since 1.22 */ final public function delayedJobsEnabled() { return $this->supportsDelayedJobs(); } /** * @return string|bool Read-only rational or false if r/w * @since 1.27 */ public function getReadOnlyReason() { return $this->readOnlyReason; } /** * Quickly check if the queue has no available (unacquired, non-delayed) jobs. * Queue classes should use caching if they are any slower without memcached. * * If caching is used, this might return false when there are actually no jobs. * If pop() is called and returns false then it should correct the cache. Also, * calling flushCaches() first prevents this. However, this affect is typically * not distinguishable from the race condition between isEmpty() and pop(). * * @return bool * @throws JobQueueError */ final public function isEmpty() { $res = $this->doIsEmpty(); return $res; } /** * @see JobQueue::isEmpty() * @return bool */ abstract protected function doIsEmpty(); /** * Get the number of available (unacquired, non-delayed) jobs in the queue. * Queue classes should use caching if they are any slower without memcached. * * If caching is used, this number might be out of date for a minute. * * @return int * @throws JobQueueError */ final public function getSize() { $res = $this->doGetSize(); return $res; } /** * @see JobQueue::getSize() * @return int */ abstract protected function doGetSize(); /** * Get the number of acquired jobs (these are temporarily out of the queue). * Queue classes should use caching if they are any slower without memcached. * * If caching is used, this number might be out of date for a minute. * * @return int * @throws JobQueueError */ final public function getAcquiredCount() { $res = $this->doGetAcquiredCount(); return $res; } /** * @see JobQueue::getAcquiredCount() * @return int */ abstract protected function doGetAcquiredCount(); /** * Get the number of delayed jobs (these are temporarily out of the queue). * Queue classes should use caching if they are any slower without memcached. * * If caching is used, this number might be out of date for a minute. * * @return int * @throws JobQueueError * @since 1.22 */ final public function getDelayedCount() { $res = $this->doGetDelayedCount(); return $res; } /** * @see JobQueue::getDelayedCount() * @return int */ protected function doGetDelayedCount() { return 0; // not implemented } /** * Get the number of acquired jobs that can no longer be attempted. * Queue classes should use caching if they are any slower without memcached. * * If caching is used, this number might be out of date for a minute. * * @return int * @throws JobQueueError */ final public function getAbandonedCount() { $res = $this->doGetAbandonedCount(); return $res; } /** * @see JobQueue::getAbandonedCount() * @return int */ protected function doGetAbandonedCount() { return 0; // not implemented } /** * Push one or more jobs into the queue. * This does not require $wgJobClasses to be set for the given job type. * Outside callers should use JobQueueGroup::push() instead of this function. * * @param IJobSpecification|IJobSpecification[] $jobs * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC) * @return void * @throws JobQueueError */ final public function push( $jobs, $flags = 0 ) { $jobs = is_array( $jobs ) ? $jobs : [ $jobs ]; $this->batchPush( $jobs, $flags ); } /** * Push a batch of jobs into the queue. * This does not require $wgJobClasses to be set for the given job type. * Outside callers should use JobQueueGroup::push() instead of this function. * * @param IJobSpecification[] $jobs * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC) * @return void * @throws MWException */ final public function batchPush( array $jobs, $flags = 0 ) { $this->assertNotReadOnly(); if ( !count( $jobs ) ) { return; // nothing to do } foreach ( $jobs as $job ) { if ( $job->getType() !== $this->type ) { throw new MWException( "Got '{$job->getType()}' job; expected a '{$this->type}' job." ); } elseif ( $job->getReleaseTimestamp() && !$this->supportsDelayedJobs() ) { throw new MWException( "Got delayed '{$job->getType()}' job; delays are not supported." ); } } $this->doBatchPush( $jobs, $flags ); $this->aggr->notifyQueueNonEmpty( $this->wiki, $this->type ); foreach ( $jobs as $job ) { if ( $job->isRootJob() ) { $this->deduplicateRootJob( $job ); } } } /** * @see JobQueue::batchPush() * @param IJobSpecification[] $jobs * @param int $flags */ abstract protected function doBatchPush( array $jobs, $flags ); /** * Pop a job off of the queue. * This requires $wgJobClasses to be set for the given job type. * Outside callers should use JobQueueGroup::pop() instead of this function. * * @throws MWException * @return Job|bool Returns false if there are no jobs */ final public function pop() { global $wgJobClasses; $this->assertNotReadOnly(); if ( $this->wiki !== wfWikiID() ) { throw new MWException( "Cannot pop '{$this->type}' job off foreign wiki queue." ); } elseif ( !isset( $wgJobClasses[$this->type] ) ) { // Do not pop jobs if there is no class for the queue type throw new MWException( "Unrecognized job type '{$this->type}'." ); } $job = $this->doPop(); if ( !$job ) { $this->aggr->notifyQueueEmpty( $this->wiki, $this->type ); } // Flag this job as an old duplicate based on its "root" job... try { if ( $job && $this->isRootJobOldDuplicate( $job ) ) { JobQueue::incrStats( 'dupe_pops', $this->type ); $job = DuplicateJob::newFromJob( $job ); // convert to a no-op } } catch ( Exception $e ) { // don't lose jobs over this } return $job; } /** * @see JobQueue::pop() * @return Job|bool */ abstract protected function doPop(); /** * Acknowledge that a job was completed. * * This does nothing for certain queue classes or if "claimTTL" is not set. * Outside callers should use JobQueueGroup::ack() instead of this function. * * @param Job $job * @return void * @throws MWException */ final public function ack( Job $job ) { $this->assertNotReadOnly(); if ( $job->getType() !== $this->type ) { throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." ); } $this->doAck( $job ); } /** * @see JobQueue::ack() * @param Job $job */ abstract protected function doAck( Job $job ); /** * Register the "root job" of a given job into the queue for de-duplication. * This should only be called right *after* all the new jobs have been inserted. * This is used to turn older, duplicate, job entries into no-ops. The root job * information will remain in the registry until it simply falls out of cache. * * This requires that $job has two special fields in the "params" array: * - rootJobSignature : hash (e.g. SHA1) that identifies the task * - rootJobTimestamp : TS_MW timestamp of this instance of the task * * A "root job" is a conceptual job that consist of potentially many smaller jobs * that are actually inserted into the queue. For example, "refreshLinks" jobs are * spawned when a template is edited. One can think of the task as "update links * of pages that use template X" and an instance of that task as a "root job". * However, what actually goes into the queue are range and leaf job subtypes. * Since these jobs include things like page ID ranges and DB master positions, * and can morph into smaller jobs recursively, simple duplicate detection * for individual jobs being identical (like that of job_sha1) is not useful. * * In the case of "refreshLinks", if these jobs are still in the queue when the template * is edited again, we want all of these old refreshLinks jobs for that template to become * no-ops. This can greatly reduce server load, since refreshLinks jobs involves parsing. * Essentially, the new batch of jobs belong to a new "root job" and the older ones to a * previous "root job" for the same task of "update links of pages that use template X". * * This does nothing for certain queue classes. * * @param IJobSpecification $job * @throws MWException * @return bool */ final public function deduplicateRootJob( IJobSpecification $job ) { $this->assertNotReadOnly(); if ( $job->getType() !== $this->type ) { throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." ); } return $this->doDeduplicateRootJob( $job ); } /** * @see JobQueue::deduplicateRootJob() * @param IJobSpecification $job * @throws MWException * @return bool */ protected function doDeduplicateRootJob( IJobSpecification $job ) { if ( !$job->hasRootJobParams() ) { throw new MWException( "Cannot register root job; missing parameters." ); } $params = $job->getRootJobParams(); $key = $this->getRootJobCacheKey( $params['rootJobSignature'] ); // Callers should call batchInsert() and then this function so that if the insert // fails, the de-duplication registration will be aborted. Since the insert is // deferred till "transaction idle", do the same here, so that the ordering is // maintained. Having only the de-duplication registration succeed would cause // jobs to become no-ops without any actual jobs that made them redundant. $timestamp = $this->dupCache->get( $key ); // current last timestamp of this job if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) { return true; // a newer version of this root job was enqueued } // Update the timestamp of the last root job started at the location... return $this->dupCache->set( $key, $params['rootJobTimestamp'], JobQueueDB::ROOTJOB_TTL ); } /** * Check if the "root" job of a given job has been superseded by a newer one * * @param Job $job * @throws MWException * @return bool */ final protected function isRootJobOldDuplicate( Job $job ) { if ( $job->getType() !== $this->type ) { throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." ); } $isDuplicate = $this->doIsRootJobOldDuplicate( $job ); return $isDuplicate; } /** * @see JobQueue::isRootJobOldDuplicate() * @param Job $job * @return bool */ protected function doIsRootJobOldDuplicate( Job $job ) { if ( !$job->hasRootJobParams() ) { return false; // job has no de-deplication info } $params = $job->getRootJobParams(); $key = $this->getRootJobCacheKey( $params['rootJobSignature'] ); // Get the last time this root job was enqueued $timestamp = $this->dupCache->get( $key ); // Check if a new root job was started at the location after this one's... return ( $timestamp && $timestamp > $params['rootJobTimestamp'] ); } /** * @param string $signature Hash identifier of the root job * @return string */ protected function getRootJobCacheKey( $signature ) { list( $db, $prefix ) = wfSplitWikiID( $this->wiki ); return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, 'rootjob', $signature ); } /** * Deleted all unclaimed and delayed jobs from the queue * * @throws JobQueueError * @since 1.22 * @return void */ final public function delete() { $this->assertNotReadOnly(); $this->doDelete(); } /** * @see JobQueue::delete() * @throws MWException */ protected function doDelete() { throw new MWException( "This method is not implemented." ); } /** * Wait for any replica DBs or backup servers to catch up. * * This does nothing for certain queue classes. * * @return void * @throws JobQueueError */ final public function waitForBackups() { $this->doWaitForBackups(); } /** * @see JobQueue::waitForBackups() * @return void */ protected function doWaitForBackups() { } /** * Clear any process and persistent caches * * @return void */ final public function flushCaches() { $this->doFlushCaches(); } /** * @see JobQueue::flushCaches() * @return void */ protected function doFlushCaches() { } /** * Get an iterator to traverse over all available jobs in this queue. * This does not include jobs that are currently acquired or delayed. * Note: results may be stale if the queue is concurrently modified. * * @return Iterator * @throws JobQueueError */ abstract public function getAllQueuedJobs(); /** * Get an iterator to traverse over all delayed jobs in this queue. * Note: results may be stale if the queue is concurrently modified. * * @return Iterator * @throws JobQueueError * @since 1.22 */ public function getAllDelayedJobs() { return new ArrayIterator( [] ); // not implemented } /** * Get an iterator to traverse over all claimed jobs in this queue * * Callers should be quick to iterator over it or few results * will be returned due to jobs being acknowledged and deleted * * @return Iterator * @throws JobQueueError * @since 1.26 */ public function getAllAcquiredJobs() { return new ArrayIterator( [] ); // not implemented } /** * Get an iterator to traverse over all abandoned jobs in this queue * * @return Iterator * @throws JobQueueError * @since 1.25 */ public function getAllAbandonedJobs() { return new ArrayIterator( [] ); // not implemented } /** * Do not use this function outside of JobQueue/JobQueueGroup * * @return string * @since 1.22 */ public function getCoalesceLocationInternal() { return null; } /** * Check whether each of the given queues are empty. * This is used for batching checks for queues stored at the same place. * * @param array $types List of queues types * @return array|null (list of non-empty queue types) or null if unsupported * @throws MWException * @since 1.22 */ final public function getSiblingQueuesWithJobs( array $types ) { return $this->doGetSiblingQueuesWithJobs( $types ); } /** * @see JobQueue::getSiblingQueuesWithJobs() * @param array $types List of queues types * @return array|null (list of queue types) or null if unsupported */ protected function doGetSiblingQueuesWithJobs( array $types ) { return null; // not supported } /** * Check the size of each of the given queues. * For queues not served by the same store as this one, 0 is returned. * This is used for batching checks for queues stored at the same place. * * @param array $types List of queues types * @return array|null (job type => whether queue is empty) or null if unsupported * @throws MWException * @since 1.22 */ final public function getSiblingQueueSizes( array $types ) { return $this->doGetSiblingQueueSizes( $types ); } /** * @see JobQueue::getSiblingQueuesSize() * @param array $types List of queues types * @return array|null (list of queue types) or null if unsupported */ protected function doGetSiblingQueueSizes( array $types ) { return null; // not supported } /** * @throws JobQueueReadOnlyError */ protected function assertNotReadOnly() { if ( $this->readOnlyReason !== false ) { throw new JobQueueReadOnlyError( "Job queue is read-only: {$this->readOnlyReason}" ); } } /** * Call wfIncrStats() for the queue overall and for the queue type * * @param string $key Event type * @param string $type Job type * @param int $delta * @since 1.22 */ public static function incrStats( $key, $type, $delta = 1 ) { static $stats; if ( !$stats ) { $stats = MediaWikiServices::getInstance()->getStatsdDataFactory(); } $stats->updateCount( "jobqueue.{$key}.all", $delta ); $stats->updateCount( "jobqueue.{$key}.{$type}", $delta ); } } /** * @ingroup JobQueue * @since 1.22 */ class JobQueueError extends MWException { } class JobQueueConnectionError extends JobQueueError { } class JobQueueReadOnlyError extends JobQueueError { }