Merge "Revert "Avoid doNotifyQueueEmpty() race conditions for Redis""

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

<?php
/**
 * Job queue task 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
 */

/**
 * Class to both describe a background job and handle jobs.
 * The queue aspects of this class are now deprecated.
 * Using the class to push jobs onto queues is deprecated (use JobSpecification).
 *
 * @ingroup JobQueue
 */
abstract class Job implements IJobSpecification {
        /** @var string */
        public $command;

        /** @var array Array of job parameters */
        public $params;

        /** @var array Additional queue metadata */
        public $metadata = array();

        /** @var Title */
        protected $title;

        /** @var bool Expensive jobs may set this to true */
        protected $removeDuplicates;

        /** @var string Text for error that occurred last */
        protected $error;

        /**
         * Run the job
         * @return bool Success
         */
        abstract public function run();

        /**
         * Create the appropriate object to handle a specific job
         *
         * @param string $command Job command
         * @param Title $title Associated title
         * @param array $params Job parameters
         * @throws MWException
         * @return Job
         */
        public static function factory( $command, Title $title, $params = array() ) {
                global $wgJobClasses;

                if ( isset( $wgJobClasses[$command] ) ) {
                        $class = $wgJobClasses[$command];

                        $job = new $class( $title, $params );
                        $job->command = $command;

                        return $job;
                }

                throw new InvalidArgumentException( "Invalid job command '{$command}'" );
        }

        /**
         * @param string $command
         * @param Title $title
         * @param array|bool $params Can not be === true
         */
        public function __construct( $command, $title, $params = false ) {
                $this->command = $command;
                $this->title = $title;
                $this->params = is_array( $params ) ? $params : array(); // sanity

                // expensive jobs may set this to true
                $this->removeDuplicates = false;
        }

        /**
         * Batch-insert a group of jobs into the queue.
         * This will be wrapped in a transaction with a forced commit.
         *
         * This may add duplicate at insert time, but they will be
         * removed later on, when the first one is popped.
         *
         * @param Job[] $jobs Array of Job objects
         * @return bool
         * @deprecated since 1.21
         */
        public static function batchInsert( $jobs ) {
                wfDeprecated( __METHOD__, '1.21' );
                JobQueueGroup::singleton()->push( $jobs );
                return true;
        }

        /**
         * @return string
         */
        public function getType() {
                return $this->command;
        }

        /**
         * @return Title
         */
        public function getTitle() {
                return $this->title;
        }

        /**
         * @return array
         */
        public function getParams() {
                return $this->params;
        }

        /**
         * @return int|null UNIX timestamp to delay running this job until, otherwise null
         * @since 1.22
         */
        public function getReleaseTimestamp() {
                return isset( $this->params['jobReleaseTimestamp'] )
                        ? wfTimestampOrNull( TS_UNIX, $this->params['jobReleaseTimestamp'] )
                        : null;
        }

        /**
         * @return int|null UNIX timestamp of when the job was queued, or null
         * @since 1.26
         */
        public function getQueuedTimestamp() {
                return isset( $this->metadata['timestamp'] )
                        ? wfTimestampOrNull( TS_UNIX, $this->metadata['timestamp'] )
                        : null;
        }

        /**
         * @return int|null UNIX timestamp of when the job was runnable, or null
         * @since 1.26
         */
        public function getReadyTimestamp() {
                return $this->getReleaseTimestamp() ?: $this->getQueuedTimestamp();
        }

        /**
         * Whether the queue should reject insertion of this job if a duplicate exists
         *
         * This can be used to avoid duplicated effort or combined with delayed jobs to
         * coalesce updates into larger batches. Claimed jobs are never treated as
         * duplicates of new jobs, and some queues may allow a few duplicates due to
         * network partitions and fail-over. Thus, additional locking is needed to
         * enforce mutual exclusion if this is really needed.
         *
         * @return bool
         */
        public function ignoreDuplicates() {
                return $this->removeDuplicates;
        }

        /**
         * @return bool Whether this job can be retried on failure by job runners
         * @since 1.21
         */
        public function allowRetries() {
                return true;
        }

        /**
         * @return int Number of actually "work items" handled in this job
         * @see $wgJobBackoffThrottling
         * @since 1.23
         */
        public function workItemCount() {
                return 1;
        }

        /**
         * Subclasses may need to override this to make duplication detection work.
         * The resulting map conveys everything that makes the job unique. This is
         * only checked if ignoreDuplicates() returns true, meaning that duplicate
         * jobs are supposed to be ignored.
         *
         * @return array Map of key/values
         * @since 1.21
         */
        public function getDeduplicationInfo() {
                $info = array(
                        'type' => $this->getType(),
                        'namespace' => $this->getTitle()->getNamespace(),
                        'title' => $this->getTitle()->getDBkey(),
                        'params' => $this->getParams()
                );
                if ( is_array( $info['params'] ) ) {
                        // Identical jobs with different "root" jobs should count as duplicates
                        unset( $info['params']['rootJobSignature'] );
                        unset( $info['params']['rootJobTimestamp'] );
                        // Likewise for jobs with different delay times
                        unset( $info['params']['jobReleaseTimestamp'] );
                        // Queues pack and hash this array, so normalize the order
                        ksort( $info['params'] );
                }

                return $info;
        }

        /**
         * Get "root job" parameters for a task
         *
         * This is used to no-op redundant jobs, including child jobs of jobs,
         * as long as the children inherit the root job parameters. When a job
         * with root job parameters and "rootJobIsSelf" set is pushed, the
         * deduplicateRootJob() method is automatically called on it. If the
         * root job is only virtual and not actually pushed (e.g. the sub-jobs
         * are inserted directly), then call deduplicateRootJob() directly.
         *
         * @see JobQueue::deduplicateRootJob()
         *
         * @param string $key A key that identifies the task
         * @return array Map of:
         *   - rootJobIsSelf    : true
         *   - rootJobSignature : hash (e.g. SHA1) that identifies the task
         *   - rootJobTimestamp : TS_MW timestamp of this instance of the task
         * @since 1.21
         */
        public static function newRootJobParams( $key ) {
                return array(
                        'rootJobIsSelf'    => true,
                        'rootJobSignature' => sha1( $key ),
                        'rootJobTimestamp' => wfTimestampNow()
                );
        }

        /**
         * @see JobQueue::deduplicateRootJob()
         * @return array
         * @since 1.21
         */
        public function getRootJobParams() {
                return array(
                        'rootJobSignature' => isset( $this->params['rootJobSignature'] )
                                ? $this->params['rootJobSignature']
                                : null,
                        'rootJobTimestamp' => isset( $this->params['rootJobTimestamp'] )
                                ? $this->params['rootJobTimestamp']
                                : null
                );
        }

        /**
         * @see JobQueue::deduplicateRootJob()
         * @return bool
         * @since 1.22
         */
        public function hasRootJobParams() {
                return isset( $this->params['rootJobSignature'] )
                        && isset( $this->params['rootJobTimestamp'] );
        }

        /**
         * @see JobQueue::deduplicateRootJob()
         * @return bool Whether this is job is a root job
         */
        public function isRootJob() {
                return $this->hasRootJobParams() && !empty( $this->params['rootJobIsSelf'] );
        }

        /**
         * Insert a single job into the queue.
         * @return bool True on success
         * @deprecated since 1.21
         */
        public function insert() {
                JobQueueGroup::singleton()->push( $this );
                return true;
        }

        /**
         * @return string
         */
        public function toString() {
                $truncFunc = function ( $value ) {
                        $value = (string)$value;
                        if ( mb_strlen( $value ) > 1024 ) {
                                $value = "string(" . mb_strlen( $value ) . ")";
                        }
                        return $value;
                };

                $paramString = '';
                if ( $this->params ) {
                        foreach ( $this->params as $key => $value ) {
                                if ( $paramString != '' ) {
                                        $paramString .= ' ';
                                }
                                if ( is_array( $value ) ) {
                                        $filteredValue = array();
                                        foreach ( $value as $k => $v ) {
                                                if ( is_scalar( $v ) ) {
                                                        $filteredValue[$k] = $truncFunc( $v );
                                                } else {
                                                        $filteredValue = null;
                                                        break;
                                                }
                                        }
                                        if ( $filteredValue && count( $filteredValue ) < 10 ) {
                                                $value = FormatJson::encode( $filteredValue );
                                        } else {
                                                $value = "array(" . count( $value ) . ")";
                                        }
                                } elseif ( is_object( $value ) && !method_exists( $value, '__toString' ) ) {
                                        $value = "object(" . get_class( $value ) . ")";
                                }

                                $paramString .= "$key={$truncFunc( $value )}";
                        }
                }

                $metaString = '';
                foreach ( $this->metadata as $key => $value ) {
                        if ( is_scalar( $value ) && mb_strlen( $value ) < 1024 ) {
                                $metaString .= ( $metaString ? ",$key=$value" : "$key=$value" );
                        }
                }

                $s = $this->command;
                if ( is_object( $this->title ) ) {
                        $s .= " {$this->title->getPrefixedDBkey()}";
                }
                if ( $paramString != '' ) {
                        $s .= " $paramString";
                }
                if ( $metaString != '' ) {
                        $s .= " ($metaString)";
                }

                return $s;
        }

        protected function setLastError( $error ) {
                $this->error = $error;
        }

        public function getLastError() {
                return $this->error;
        }
}