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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 {
- protected $wiki; // string; wiki ID
- protected $type; // string; job type
- protected $order; // string; job priority for pop()
- protected $claimTTL; // integer; seconds
- protected $maxTries; // integer; maximum number of times to try a job
- protected $checkDelay; // boolean; allow delayed jobs
-
- /** @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 $params array
- */
- 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 $params array
- * @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 boolean 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 integer
- * @throws JobQueueError
- */
- final public function getSize() {
- wfProfileIn( __METHOD__ );
- $res = $this->doGetSize();
- wfProfileOut( __METHOD__ );
- return $res;
- }
-
- /**
- * @see JobQueue::getSize()
- * @return integer
- */
- 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 integer
- * @throws JobQueueError
- */
- final public function getAcquiredCount() {
- wfProfileIn( __METHOD__ );
- $res = $this->doGetAcquiredCount();
- wfProfileOut( __METHOD__ );
- return $res;
- }
-
- /**
- * @see JobQueue::getAcquiredCount()
- * @return integer
- */
- 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 integer
- * @throws JobQueueError
- * @since 1.22
- */
- final public function getDelayedCount() {
- wfProfileIn( __METHOD__ );
- $res = $this->doGetDelayedCount();
- wfProfileOut( __METHOD__ );
- return $res;
- }
-
- /**
- * @see JobQueue::getDelayedCount()
- * @return integer
- */
- 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 integer
- * @throws JobQueueError
- */
- final public function getAbandonedCount() {
- wfProfileIn( __METHOD__ );
- $res = $this->doGetAbandonedCount();
- wfProfileOut( __METHOD__ );
- return $res;
- }
-
- /**
- * @see JobQueue::getAbandonedCount()
- * @return integer
- */
- protected function doGetAbandonedCount() {
- return 0; // not implemented
- }
-
- /**
- * Push a single 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 $jobs Job|Array
- * @param $flags integer Bitfield (supports JobQueue::QOS_ATOMIC)
- * @return bool Returns false on failure
- * @throws JobQueueError
- */
- final public function push( $jobs, $flags = 0 ) {
- return $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 $flags integer Bitfield (supports JobQueue::QOS_ATOMIC)
- * @return bool Returns false on failure
- * @throws JobQueueError
- */
- final public function batchPush( array $jobs, $flags = 0 ) {
- if ( !count( $jobs ) ) {
- return true; // 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__ );
- $ok = $this->doBatchPush( $jobs, $flags );
- wfProfileOut( __METHOD__ );
- return $ok;
- }
-
- /**
- * @see JobQueue::batchPush()
- * @return bool
- */
- 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.
- *
- * @return Job|bool Returns false if there are no jobs
- * @throws JobQueueError
- */
- 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 );
- $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 bool
- * @throws JobQueueError
- */
- final public function ack( Job $job ) {
- if ( $job->getType() !== $this->type ) {
- throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
- }
- wfProfileIn( __METHOD__ );
- $ok = $this->doAck( $job );
- wfProfileOut( __METHOD__ );
- return $ok;
- }
-
- /**
- * @see JobQueue::ack()
- * @return bool
- */
- 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 potentially many refreshLinks2 jobs.
- * Since these jobs include things like page ID ranges and DB master positions, and morph
- * into smaller refreshLinks2 jobs recursively, simple duplicate detection (like job_sha1)
- * for individual jobs being identical 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
- * @return bool
- * @throws JobQueueError
- */
- 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
- * @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
- * @return bool
- * @throws JobQueueError
- */
- 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
- *
- * @return bool Success
- * @throws JobQueueError
- * @since 1.22
- */
- final public function delete() {
- wfProfileIn( __METHOD__ );
- $res = $this->doDelete();
- wfProfileOut( __METHOD__ );
- return $res;
- }
-
- /**
- * @see JobQueue::delete()
- * @return bool Success
- */
- 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 integer $delta
- * @since 1.22
- */
- public static function incrStats( $key, $type, $delta = 1 ) {
- wfIncrStats( $key, $delta );
- wfIncrStats( "{$key}-{$type}", $delta );
- }
-
- /**
- * Namespace the queue with a key to isolate it for testing
- *
- * @param $key string
- * @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 {}