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+<?php
+/**
+ * Job queue base code.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @defgroup JobQueue JobQueue
+ * @author Aaron Schulz
+ */
+
+/**
+ * Class to handle enqueueing and running of background jobs
+ *
+ * @ingroup JobQueue
+ * @since 1.21
+ */
+abstract class JobQueue {
+ /** @var string Wiki ID */
+ protected $wiki;
+
+ /** @var string Job type */
+ protected $type;
+
+ /** @var string Job priority for pop() */
+ protected $order;
+
+ /** @var int Time to live in seconds */
+ protected $claimTTL;
+
+ /** @var int Maximum number of times to try a job */
+ protected $maxTries;
+
+ /** @var bool Allow delayed jobs */
+ protected $checkDelay;
+
+ /** @var BagOStuff */
+ protected $dupCache;
+
+ const QOS_ATOMIC = 1; // integer; "all-or-nothing" job insertions
+
+ const ROOTJOB_TTL = 2419200; // integer; seconds to remember root jobs (28 days)
+
+ /**
+ * @param array $params
+ * @throws MWException
+ */
+ protected function __construct( array $params ) {
+ $this->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->checkDelay = !empty( $params['checkDelay'] );
+ if ( $this->checkDelay && !$this->supportsDelayedJobs() ) {
+ throw new MWException( __CLASS__ . " does not support delayed jobs." );
+ }
+ $this->dupCache = wfGetCache( CACHE_ANYTHING );
+ }
+
+ /**
+ * 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 simple means re-inserting them into the queue. Jobs can be
+ * attempted up to three times before being discarded.
+ * - checkDelay : If supported, respect Job::getReleaseTimestamp() in the push functions.
+ * This lets delayed jobs wait in a staging area until a given timestamp is
+ * reached, at which point they will enter the queue. If this is not enabled
+ * or not supported, an exception will be thrown on delayed job insertion.
+ *
+ * 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;
+ }
+
+ /**
+ * @return bool Whether delayed jobs are enabled
+ * @since 1.22
+ */
+ final public function delayedJobsEnabled() {
+ return $this->checkDelay;
+ }
+
+ /**
+ * 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
+ }
+
+ /**
+ * 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() {
+ wfProfileIn( __METHOD__ );
+ $res = $this->doIsEmpty();
+ wfProfileOut( __METHOD__ );
+
+ 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() {
+ wfProfileIn( __METHOD__ );
+ $res = $this->doGetSize();
+ wfProfileOut( __METHOD__ );
+
+ 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() {
+ wfProfileIn( __METHOD__ );
+ $res = $this->doGetAcquiredCount();
+ wfProfileOut( __METHOD__ );
+
+ 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() {
+ wfProfileIn( __METHOD__ );
+ $res = $this->doGetDelayedCount();
+ wfProfileOut( __METHOD__ );
+
+ 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() {
+ wfProfileIn( __METHOD__ );
+ $res = $this->doGetAbandonedCount();
+ wfProfileOut( __METHOD__ );
+
+ 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 Job|array $jobs A single job or an array of Jobs
+ * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
+ * @return void
+ * @throws JobQueueError
+ */
+ final public function push( $jobs, $flags = 0 ) {
+ $this->batchPush( is_array( $jobs ) ? $jobs : array( $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 array $jobs List of Jobs
+ * @param int $flags Bitfield (supports JobQueue::QOS_ATOMIC)
+ * @return void
+ * @throws MWException
+ */
+ final public function batchPush( array $jobs, $flags = 0 ) {
+ 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->checkDelay ) {
+ throw new MWException(
+ "Got delayed '{$job->getType()}' job; delays are not supported." );
+ }
+ }
+
+ wfProfileIn( __METHOD__ );
+ $this->doBatchPush( $jobs, $flags );
+ wfProfileOut( __METHOD__ );
+ }
+
+ /**
+ * @see JobQueue::batchPush()
+ * @param array $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;
+
+ 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}'." );
+ }
+
+ wfProfileIn( __METHOD__ );
+ $job = $this->doPop();
+ wfProfileOut( __METHOD__ );
+
+ // Flag this job as an old duplicate based on its "root" job...
+ try {
+ if ( $job && $this->isRootJobOldDuplicate( $job ) ) {
+ JobQueue::incrStats( 'job-pop-duplicate', $this->type, 1, $this->wiki );
+ $job = DuplicateJob::newFromJob( $job ); // convert to a no-op
+ }
+ } catch ( MWException $e ) {
+ // don't lose jobs over this
+ }
+
+ return $job;
+ }
+
+ /**
+ * @see JobQueue::pop()
+ * @return Job
+ */
+ 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 ) {
+ if ( $job->getType() !== $this->type ) {
+ throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
+ }
+ wfProfileIn( __METHOD__ );
+ $this->doAck( $job );
+ wfProfileOut( __METHOD__ );
+ }
+
+ /**
+ * @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 Job $job
+ * @throws MWException
+ * @return bool
+ */
+ final public function deduplicateRootJob( Job $job ) {
+ if ( $job->getType() !== $this->type ) {
+ throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
+ }
+ wfProfileIn( __METHOD__ );
+ $ok = $this->doDeduplicateRootJob( $job );
+ wfProfileOut( __METHOD__ );
+
+ return $ok;
+ }
+
+ /**
+ * @see JobQueue::deduplicateRootJob()
+ * @param Job $job
+ * @throws MWException
+ * @return bool
+ */
+ protected function doDeduplicateRootJob( Job $job ) {
+ if ( !$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}'." );
+ }
+ wfProfileIn( __METHOD__ );
+ $isDuplicate = $this->doIsRootJobOldDuplicate( $job );
+ wfProfileOut( __METHOD__ );
+
+ 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() {
+ wfProfileIn( __METHOD__ );
+ $this->doDelete();
+ wfProfileOut( __METHOD__ );
+ }
+
+ /**
+ * @see JobQueue::delete()
+ * @throws MWException
+ */
+ protected function doDelete() {
+ throw new MWException( "This method is not implemented." );
+ }
+
+ /**
+ * Wait for any slaves or backup servers to catch up.
+ *
+ * This does nothing for certain queue classes.
+ *
+ * @return void
+ * @throws JobQueueError
+ */
+ final public function waitForBackups() {
+ wfProfileIn( __METHOD__ );
+ $this->doWaitForBackups();
+ wfProfileOut( __METHOD__ );
+ }
+
+ /**
+ * @see JobQueue::waitForBackups()
+ * @return void
+ */
+ protected function doWaitForBackups() {
+ }
+
+ /**
+ * Return a map of task names to task definition maps.
+ * A "task" is a fast periodic queue maintenance action.
+ * Mutually exclusive tasks must implement their own locking in the callback.
+ *
+ * Each task value is an associative array with:
+ * - name : the name of the task
+ * - callback : a PHP callable that performs the task
+ * - period : the period in seconds corresponding to the task frequency
+ *
+ * @return array
+ */
+ final public function getPeriodicTasks() {
+ $tasks = $this->doGetPeriodicTasks();
+ foreach ( $tasks as $name => &$def ) {
+ $def['name'] = $name;
+ }
+
+ return $tasks;
+ }
+
+ /**
+ * @see JobQueue::getPeriodicTasks()
+ * @return array
+ */
+ protected function doGetPeriodicTasks() {
+ return array();
+ }
+
+ /**
+ * Clear any process and persistent caches
+ *
+ * @return void
+ */
+ final public function flushCaches() {
+ wfProfileIn( __METHOD__ );
+ $this->doFlushCaches();
+ wfProfileOut( __METHOD__ );
+ }
+
+ /**
+ * @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( array() ); // 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 ) {
+ $section = new ProfileSection( __METHOD__ );
+
+ 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 ) {
+ $section = new ProfileSection( __METHOD__ );
+
+ 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
+ }
+
+ /**
+ * Call wfIncrStats() for the queue overall and for the queue type
+ *
+ * @param string $key Event type
+ * @param string $type Job type
+ * @param int $delta
+ * @param string $wiki Wiki ID (added in 1.23)
+ * @since 1.22
+ */
+ public static function incrStats( $key, $type, $delta = 1, $wiki = null ) {
+ wfIncrStats( $key, $delta );
+ wfIncrStats( "{$key}-{$type}", $delta );
+ if ( $wiki !== null ) {
+ wfIncrStats( "{$key}-{$type}-{$wiki}", $delta );
+ }
+ }
+
+ /**
+ * Namespace the queue with a key to isolate it for testing
+ *
+ * @param string $key
+ * @return void
+ * @throws MWException
+ */
+ public function setTestingPrefix( $key ) {
+ throw new MWException( "Queue namespacing not supported for this queue type." );
+ }
+}
+
+/**
+ * @ingroup JobQueue
+ * @since 1.22
+ */
+class JobQueueError extends MWException {
+}
+
+class JobQueueConnectionError extends JobQueueError {
+}
generated by cgit v1.2.2 (git 2.25.0) at 2024-04-18 22:37:36 +0000