Merge "Update docs/hooks.txt for ShowSearchHitTitle"

[mediawiki.git] / includes / jobqueue / JobQueueGroup.php

<?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
 * @author Aaron Schulz
 */

/**
 * Class to handle enqueueing of background jobs
 *
 * @ingroup JobQueue
 * @since 1.21
 */
class JobQueueGroup {
        /** @var JobQueueGroup[] */
        protected static $instances = [];

        /** @var ProcessCacheLRU */
        protected $cache;

        /** @var string Wiki ID */
        protected $wiki;
        /** @var string|bool Read only rationale (or false if r/w) */
        protected $readOnlyReason;

        /** @var array Map of (bucket => (queue => JobQueue, types => list of types) */
        protected $coalescedQueues;

        /** @var Job[] */
        protected $bufferedJobs = [];

        const TYPE_DEFAULT = 1; // integer; jobs popped by default
        const TYPE_ANY = 2; // integer; any job

        const USE_CACHE = 1; // integer; use process or persistent cache

        const PROC_CACHE_TTL = 15; // integer; seconds

        const CACHE_VERSION = 1; // integer; cache version

        /**
         * @param string $wiki Wiki ID
         * @param string|bool $readOnlyReason Read-only reason or false
         */
        protected function __construct( $wiki, $readOnlyReason ) {
                $this->wiki = $wiki;
                $this->readOnlyReason = $readOnlyReason;
                $this->cache = new ProcessCacheLRU( 10 );
        }

        /**
         * @param bool|string $wiki Wiki ID
         * @return JobQueueGroup
         */
        public static function singleton( $wiki = false ) {
                $wiki = ( $wiki === false ) ? wfWikiID() : $wiki;
                if ( !isset( self::$instances[$wiki] ) ) {
                        self::$instances[$wiki] = new self( $wiki, wfConfiguredReadOnlyReason() );
                }

                return self::$instances[$wiki];
        }

        /**
         * Destroy the singleton instances
         *
         * @return void
         */
        public static function destroySingletons() {
                self::$instances = [];
        }

        /**
         * Get the job queue object for a given queue type
         *
         * @param string $type
         * @return JobQueue
         */
        public function get( $type ) {
                global $wgJobTypeConf;

                $conf = [ 'wiki' => $this->wiki, 'type' => $type ];
                if ( isset( $wgJobTypeConf[$type] ) ) {
                        $conf = $conf + $wgJobTypeConf[$type];
                } else {
                        $conf = $conf + $wgJobTypeConf['default'];
                }
                $conf['aggregator'] = JobQueueAggregator::singleton();
                if ( $this->readOnlyReason !== false ) {
                        $conf['readOnlyReason'] = $this->readOnlyReason;
                }

                return JobQueue::factory( $conf );
        }

        /**
         * Insert jobs into the respective queues of which they belong
         *
         * This inserts the jobs into the queue specified by $wgJobTypeConf
         * and updates the aggregate job queue information cache as needed.
         *
         * @param IJobSpecification|IJobSpecification[] $jobs A single Job or a list of Jobs
         * @throws InvalidArgumentException
         * @return void
         */
        public function push( $jobs ) {
                global $wgJobTypesExcludedFromDefaultQueue;

                $jobs = is_array( $jobs ) ? $jobs : [ $jobs ];
                if ( !count( $jobs ) ) {
                        return;
                }

                $this->assertValidJobs( $jobs );

                $jobsByType = []; // (job type => list of jobs)
                foreach ( $jobs as $job ) {
                        $jobsByType[$job->getType()][] = $job;
                }

                foreach ( $jobsByType as $type => $jobs ) {
                        $this->get( $type )->push( $jobs );
                }

                if ( $this->cache->has( 'queues-ready', 'list' ) ) {
                        $list = $this->cache->get( 'queues-ready', 'list' );
                        if ( count( array_diff( array_keys( $jobsByType ), $list ) ) ) {
                                $this->cache->clear( 'queues-ready' );
                        }
                }

                $cache = ObjectCache::getLocalClusterInstance();
                $cache->set(
                        $cache->makeGlobalKey( 'jobqueue', $this->wiki, 'hasjobs', self::TYPE_ANY ),
                        'true',
                        15
                );
                if ( array_diff( array_keys( $jobsByType ), $wgJobTypesExcludedFromDefaultQueue ) ) {
                        $cache->set(
                                $cache->makeGlobalKey( 'jobqueue', $this->wiki, 'hasjobs', self::TYPE_DEFAULT ),
                                'true',
                                15
                        );
                }
        }

        /**
         * Buffer jobs for insertion via push() or call it now if in CLI mode
         *
         * Note that MediaWiki::restInPeace() calls pushLazyJobs()
         *
         * @param IJobSpecification|IJobSpecification[] $jobs A single Job or a list of Jobs
         * @return void
         * @since 1.26
         */
        public function lazyPush( $jobs ) {
                if ( PHP_SAPI === 'cli' ) {
                        $this->push( $jobs );
                        return;
                }

                $jobs = is_array( $jobs ) ? $jobs : [ $jobs ];

                // Throw errors now instead of on push(), when other jobs may be buffered
                $this->assertValidJobs( $jobs );

                $this->bufferedJobs = array_merge( $this->bufferedJobs, $jobs );
        }

        /**
         * Push all jobs buffered via lazyPush() into their respective queues
         *
         * @return void
         * @since 1.26
         */
        public static function pushLazyJobs() {
                foreach ( self::$instances as $group ) {
                        try {
                                $group->push( $group->bufferedJobs );
                                $group->bufferedJobs = [];
                        } catch ( Exception $e ) {
                                // Get in as many jobs as possible and let other post-send updates happen
                                MWExceptionHandler::logException( $e );
                        }
                }
        }

        /**
         * Pop a job off one of the job queues
         *
         * This pops a job off a queue as specified by $wgJobTypeConf and
         * updates the aggregate job queue information cache as needed.
         *
         * @param int|string $qtype JobQueueGroup::TYPE_* constant or job type string
         * @param int $flags Bitfield of JobQueueGroup::USE_* constants
         * @param array $blacklist List of job types to ignore
         * @return Job|bool Returns false on failure
         */
        public function pop( $qtype = self::TYPE_DEFAULT, $flags = 0, array $blacklist = [] ) {
                $job = false;

                if ( is_string( $qtype ) ) { // specific job type
                        if ( !in_array( $qtype, $blacklist ) ) {
                                $job = $this->get( $qtype )->pop();
                        }
                } else { // any job in the "default" jobs types
                        if ( $flags & self::USE_CACHE ) {
                                if ( !$this->cache->has( 'queues-ready', 'list', self::PROC_CACHE_TTL ) ) {
                                        $this->cache->set( 'queues-ready', 'list', $this->getQueuesWithJobs() );
                                }
                                $types = $this->cache->get( 'queues-ready', 'list' );
                        } else {
                                $types = $this->getQueuesWithJobs();
                        }

                        if ( $qtype == self::TYPE_DEFAULT ) {
                                $types = array_intersect( $types, $this->getDefaultQueueTypes() );
                        }

                        $types = array_diff( $types, $blacklist ); // avoid selected types
                        shuffle( $types ); // avoid starvation

                        foreach ( $types as $type ) { // for each queue...
                                $job = $this->get( $type )->pop();
                                if ( $job ) { // found
                                        break;
                                } else { // not found
                                        $this->cache->clear( 'queues-ready' );
                                }
                        }
                }

                return $job;
        }

        /**
         * Acknowledge that a job was completed
         *
         * @param Job $job
         * @return void
         */
        public function ack( Job $job ) {
                $this->get( $job->getType() )->ack( $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.
         *
         * @param Job $job
         * @return bool
         */
        public function deduplicateRootJob( Job $job ) {
                return $this->get( $job->getType() )->deduplicateRootJob( $job );
        }

        /**
         * Wait for any replica DBs or backup queue servers to catch up.
         *
         * This does nothing for certain queue classes.
         *
         * @return void
         */
        public function waitForBackups() {
                global $wgJobTypeConf;

                // Try to avoid doing this more than once per queue storage medium
                foreach ( $wgJobTypeConf as $type => $conf ) {
                        $this->get( $type )->waitForBackups();
                }
        }

        /**
         * Get the list of queue types
         *
         * @return array List of strings
         */
        public function getQueueTypes() {
                return array_keys( $this->getCachedConfigVar( 'wgJobClasses' ) );
        }

        /**
         * Get the list of default queue types
         *
         * @return array List of strings
         */
        public function getDefaultQueueTypes() {
                global $wgJobTypesExcludedFromDefaultQueue;

                return array_diff( $this->getQueueTypes(), $wgJobTypesExcludedFromDefaultQueue );
        }

        /**
         * Check if there are any queues with jobs (this is cached)
         *
         * @param int $type JobQueueGroup::TYPE_* constant
         * @return bool
         * @since 1.23
         */
        public function queuesHaveJobs( $type = self::TYPE_ANY ) {
                $cache = ObjectCache::getLocalClusterInstance();
                $key = $cache->makeGlobalKey( 'jobqueue', $this->wiki, 'hasjobs', $type );

                $value = $cache->get( $key );
                if ( $value === false ) {
                        $queues = $this->getQueuesWithJobs();
                        if ( $type == self::TYPE_DEFAULT ) {
                                $queues = array_intersect( $queues, $this->getDefaultQueueTypes() );
                        }
                        $value = count( $queues ) ? 'true' : 'false';
                        $cache->add( $key, $value, 15 );
                }

                return ( $value === 'true' );
        }

        /**
         * Get the list of job types that have non-empty queues
         *
         * @return array List of job types that have non-empty queues
         */
        public function getQueuesWithJobs() {
                $types = [];
                foreach ( $this->getCoalescedQueues() as $info ) {
                        $nonEmpty = $info['queue']->getSiblingQueuesWithJobs( $this->getQueueTypes() );
                        if ( is_array( $nonEmpty ) ) { // batching features supported
                                $types = array_merge( $types, $nonEmpty );
                        } else { // we have to go through the queues in the bucket one-by-one
                                foreach ( $info['types'] as $type ) {
                                        if ( !$this->get( $type )->isEmpty() ) {
                                                $types[] = $type;
                                        }
                                }
                        }
                }

                return $types;
        }

        /**
         * Get the size of the queus for a list of job types
         *
         * @return array Map of (job type => size)
         */
        public function getQueueSizes() {
                $sizeMap = [];
                foreach ( $this->getCoalescedQueues() as $info ) {
                        $sizes = $info['queue']->getSiblingQueueSizes( $this->getQueueTypes() );
                        if ( is_array( $sizes ) ) { // batching features supported
                                $sizeMap = $sizeMap + $sizes;
                        } else { // we have to go through the queues in the bucket one-by-one
                                foreach ( $info['types'] as $type ) {
                                        $sizeMap[$type] = $this->get( $type )->getSize();
                                }
                        }
                }

                return $sizeMap;
        }

        /**
         * @return array
         */
        protected function getCoalescedQueues() {
                global $wgJobTypeConf;

                if ( $this->coalescedQueues === null ) {
                        $this->coalescedQueues = [];
                        foreach ( $wgJobTypeConf as $type => $conf ) {
                                $queue = JobQueue::factory(
                                        [ 'wiki' => $this->wiki, 'type' => 'null' ] + $conf );
                                $loc = $queue->getCoalesceLocationInternal();
                                if ( !isset( $this->coalescedQueues[$loc] ) ) {
                                        $this->coalescedQueues[$loc]['queue'] = $queue;
                                        $this->coalescedQueues[$loc]['types'] = [];
                                }
                                if ( $type === 'default' ) {
                                        $this->coalescedQueues[$loc]['types'] = array_merge(
                                                $this->coalescedQueues[$loc]['types'],
                                                array_diff( $this->getQueueTypes(), array_keys( $wgJobTypeConf ) )
                                        );
                                } else {
                                        $this->coalescedQueues[$loc]['types'][] = $type;
                                }
                        }
                }

                return $this->coalescedQueues;
        }

        /**
         * @param string $name
         * @return mixed
         */
        private function getCachedConfigVar( $name ) {
                // @TODO: cleanup this whole method with a proper config system
                if ( $this->wiki === wfWikiID() ) {
                        return $GLOBALS[$name]; // common case
                } else {
                        $wiki = $this->wiki;
                        $cache = ObjectCache::getMainWANInstance();
                        $value = $cache->getWithSetCallback(
                                $cache->makeGlobalKey( 'jobqueue', 'configvalue', $wiki, $name ),
                                $cache::TTL_DAY + mt_rand( 0, $cache::TTL_DAY ),
                                function () use ( $wiki, $name ) {
                                        global $wgConf;

                                        return [ 'v' => $wgConf->getConfig( $wiki, $name ) ];
                                },
                                [ 'pcTTL' => WANObjectCache::TTL_PROC_LONG ]
                        );

                        return $value['v'];
                }
        }

        /**
         * @param array $jobs
         * @throws InvalidArgumentException
         */
        private function assertValidJobs( array $jobs ) {
                foreach ( $jobs as $job ) { // sanity checks
                        if ( !( $job instanceof IJobSpecification ) ) {
                                throw new InvalidArgumentException( "Expected IJobSpecification objects" );
                        }
                }
        }

        function __destruct() {
                $n = count( $this->bufferedJobs );
                if ( $n > 0 ) {
                        $type = implode( ', ', array_unique( array_map( 'get_class', $this->bufferedJobs ) ) );
                        trigger_error( __METHOD__ . ": $n buffered job(s) of type(s) $type never inserted." );
                }
        }
}