+++ /dev/null
-<?php
-/**
- * Job queue base code
- *
- * @file
- * @defgroup JobQueue JobQueue
- */
-
-if ( !defined( 'MEDIAWIKI' ) ) {
- die( "This file is part of MediaWiki, it is not a valid entry point\n" );
-}
-
-/**
- * Class to both describe a background job and handle jobs.
- *
- * @ingroup JobQueue
- */
-abstract class Job {
- var $command,
- $title,
- $params,
- $id,
- $removeDuplicates,
- $error;
-
- /*-------------------------------------------------------------------------
- * Abstract functions
- *------------------------------------------------------------------------*/
-
- /**
- * Run the job
- * @return boolean success
- */
- abstract function run();
-
- /*-------------------------------------------------------------------------
- * Static functions
- *------------------------------------------------------------------------*/
-
- /**
- * Pop a job of a certain type. This tries less hard than pop() to
- * actually find a job; it may be adversely affected by concurrent job
- * runners.
- */
- static function pop_type( $type ) {
- wfProfilein( __METHOD__ );
-
- $dbw = wfGetDB( DB_MASTER );
-
- $row = $dbw->selectRow(
- 'job',
- '*',
- array( 'job_cmd' => $type ),
- __METHOD__,
- array( 'LIMIT' => 1 )
- );
-
- if ( $row === false ) {
- wfProfileOut( __METHOD__ );
- return false;
- }
-
- /* Ensure we "own" this row */
- $dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
- $affected = $dbw->affectedRows();
-
- if ( $affected == 0 ) {
- wfProfileOut( __METHOD__ );
- return false;
- }
-
- $namespace = $row->job_namespace;
- $dbkey = $row->job_title;
- $title = Title::makeTitleSafe( $namespace, $dbkey );
- $job = Job::factory( $row->job_cmd, $title, Job::extractBlob( $row->job_params ),
- $row->job_id );
-
- $dbw->delete( 'job', $job->insertFields(), __METHOD__ );
- $dbw->commit();
-
- wfProfileOut( __METHOD__ );
- return $job;
- }
-
- /**
- * Pop a job off the front of the queue
- *
- * @param $offset Integer: Number of jobs to skip
- * @return Job or false if there's no jobs
- */
- static function pop( $offset = 0 ) {
- wfProfileIn( __METHOD__ );
-
- $dbr = wfGetDB( DB_SLAVE );
-
- /* Get a job from the slave, start with an offset,
- scan full set afterwards, avoid hitting purged rows
-
- NB: If random fetch previously was used, offset
- will always be ahead of few entries
- */
-
- $row = $dbr->selectRow( 'job', '*', "job_id >= ${offset}", __METHOD__,
- array( 'ORDER BY' => 'job_id', 'LIMIT' => 1 ) );
-
- // Refetching without offset is needed as some of job IDs could have had delayed commits
- // and have lower IDs than jobs already executed, blame concurrency :)
- //
- if ( $row === false ) {
- if ( $offset != 0 ) {
- $row = $dbr->selectRow( 'job', '*', '', __METHOD__,
- array( 'ORDER BY' => 'job_id', 'LIMIT' => 1 ) );
- }
-
- if ( $row === false ) {
- wfProfileOut( __METHOD__ );
- return false;
- }
- }
-
- // Try to delete it from the master
- $dbw = wfGetDB( DB_MASTER );
- $dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
- $affected = $dbw->affectedRows();
- $dbw->commit();
-
- if ( !$affected ) {
- // Failed, someone else beat us to it
- // Try getting a random row
- $row = $dbw->selectRow( 'job', array( 'MIN(job_id) as minjob',
- 'MAX(job_id) as maxjob' ), '1=1', __METHOD__ );
- if ( $row === false || is_null( $row->minjob ) || is_null( $row->maxjob ) ) {
- // No jobs to get
- wfProfileOut( __METHOD__ );
- return false;
- }
- // Get the random row
- $row = $dbw->selectRow( 'job', '*',
- 'job_id >= ' . mt_rand( $row->minjob, $row->maxjob ), __METHOD__ );
- if ( $row === false ) {
- // Random job gone before we got the chance to select it
- // Give up
- wfProfileOut( __METHOD__ );
- return false;
- }
- // Delete the random row
- $dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
- $affected = $dbw->affectedRows();
- $dbw->commit();
-
- if ( !$affected ) {
- // Random job gone before we exclusively deleted it
- // Give up
- wfProfileOut( __METHOD__ );
- return false;
- }
- }
-
- // If execution got to here, there's a row in $row that has been deleted from the database
- // by this thread. Hence the concurrent pop was successful.
- $namespace = $row->job_namespace;
- $dbkey = $row->job_title;
- $title = Title::makeTitleSafe( $namespace, $dbkey );
- $job = Job::factory( $row->job_cmd, $title, Job::extractBlob( $row->job_params ), $row->job_id );
-
- // Remove any duplicates it may have later in the queue
- // Deadlock prone section
- $dbw->begin();
- $dbw->delete( 'job', $job->insertFields(), __METHOD__ );
- $dbw->commit();
-
- wfProfileOut( __METHOD__ );
- return $job;
- }
-
- /**
- * Create the appropriate object to handle a specific job
- *
- * @param $command String: Job command
- * @param $title Title: Associated title
- * @param $params Array: Job parameters
- * @param $id Int: Job identifier
- * @return Job
- */
- static function factory( $command, $title, $params = false, $id = 0 ) {
- global $wgJobClasses;
- if( isset( $wgJobClasses[$command] ) ) {
- $class = $wgJobClasses[$command];
- return new $class( $title, $params, $id );
- }
- throw new MWException( "Invalid job command `{$command}`" );
- }
-
- static function makeBlob( $params ) {
- if ( $params !== false ) {
- return serialize( $params );
- } else {
- return '';
- }
- }
-
- static function extractBlob( $blob ) {
- if ( (string)$blob !== '' ) {
- return unserialize( $blob );
- } else {
- return 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 $jobs array of Job objects
- */
- static function batchInsert( $jobs ) {
- if ( !count( $jobs ) ) {
- return;
- }
- $dbw = wfGetDB( DB_MASTER );
- $rows = array();
- foreach ( $jobs as $job ) {
- $rows[] = $job->insertFields();
- if ( count( $rows ) >= 50 ) {
- # Do a small transaction to avoid slave lag
- $dbw->begin();
- $dbw->insert( 'job', $rows, __METHOD__, 'IGNORE' );
- $dbw->commit();
- $rows = array();
- }
- }
- if ( $rows ) { // last chunk
- $dbw->begin();
- $dbw->insert( 'job', $rows, __METHOD__, 'IGNORE' );
- $dbw->commit();
- }
- wfIncrStats( 'job-insert', count( $jobs ) );
- }
-
- /**
- * Insert a group of jobs into the queue.
- *
- * Same as batchInsert() but does not commit and can thus
- * be rolled-back as part of a larger transaction. However,
- * large batches of jobs can cause slave lag.
- *
- * @param $jobs array of Job objects
- */
- static function safeBatchInsert( $jobs ) {
- if ( !count( $jobs ) ) {
- return;
- }
- $dbw = wfGetDB( DB_MASTER );
- $rows = array();
- foreach ( $jobs as $job ) {
- $rows[] = $job->insertFields();
- if ( count( $rows ) >= 500 ) {
- $dbw->insert( 'job', $rows, __METHOD__, 'IGNORE' );
- $rows = array();
- }
- }
- if ( $rows ) { // last chunk
- $dbw->insert( 'job', $rows, __METHOD__, 'IGNORE' );
- }
- wfIncrStats( 'job-insert', count( $jobs ) );
- }
-
- /*-------------------------------------------------------------------------
- * Non-static functions
- *------------------------------------------------------------------------*/
-
- function __construct( $command, $title, $params = false, $id = 0 ) {
- $this->command = $command;
- $this->title = $title;
- $this->params = $params;
- $this->id = $id;
-
- // A bit of premature generalisation
- // Oh well, the whole class is premature generalisation really
- $this->removeDuplicates = true;
- }
-
- /**
- * Insert a single job into the queue.
- * @return bool true on success
- */
- function insert() {
- $fields = $this->insertFields();
-
- $dbw = wfGetDB( DB_MASTER );
-
- if ( $this->removeDuplicates ) {
- $res = $dbw->select( 'job', array( '1' ), $fields, __METHOD__ );
- if ( $dbw->numRows( $res ) ) {
- return;
- }
- }
- return $dbw->insert( 'job', $fields, __METHOD__ );
- }
-
- protected function insertFields() {
- $dbw = wfGetDB( DB_MASTER );
- return array(
- 'job_id' => $dbw->nextSequenceValue( 'job_job_id_seq' ),
- 'job_cmd' => $this->command,
- 'job_namespace' => $this->title->getNamespace(),
- 'job_title' => $this->title->getDBkey(),
- 'job_params' => Job::makeBlob( $this->params )
- );
- }
-
- function toString() {
- $paramString = '';
- if ( $this->params ) {
- foreach ( $this->params as $key => $value ) {
- if ( $paramString != '' ) {
- $paramString .= ' ';
- }
- $paramString .= "$key=$value";
- }
- }
-
- if ( is_object( $this->title ) ) {
- $s = "{$this->command} " . $this->title->getPrefixedDBkey();
- if ( $paramString !== '' ) {
- $s .= ' ' . $paramString;
- }
- return $s;
- } else {
- return "{$this->command} $paramString";
- }
- }
-
- protected function setLastError( $error ) {
- $this->error = $error;
- }
-
- function getLastError() {
- return $this->error;
- }
-}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff