Your IP : 172.69.17.155
<?php
/**
* @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
*------------------------------------------------------------------------*/
/**
* @deprecated use LinksUpdate::queueRecursiveJobs()
*/
/**
* static function queueLinksJobs( $titles ) {}
*/
/**
* 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;
}
}
$offset = $row->job_id;
// 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 ) {
$dbw->begin();
$dbw->insert( 'job', $rows, __METHOD__, 'IGNORE' );
$dbw->commit();
}
}
/*-------------------------------------------------------------------------
* 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.
*/
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;
}
}
$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;
}
}