includes/JobQueue.php

   1 <?php
   2
   3 if ( !defined( 'MEDIAWIKI' ) ) {
   4         die( "This file is part of MediaWiki, it is not a valid entry point\n" );
   5 }
   6
   7 require_once('UserMailer.php');
   8
   9 /**
  10  * Class to both describe a background job and handle jobs.
  11  */
  12 abstract class Job {
  13         var $command,
  14                 $title,
  15                 $params,
  16                 $id,
  17                 $removeDuplicates,
  18                 $error;
  19
  20         /*-------------------------------------------------------------------------
  21          * Abstract functions
  22          *------------------------------------------------------------------------*/
  23
  24         /**
  25          * Run the job
  26          * @return boolean success
  27          */
  28         abstract function run();
  29
  30         /*-------------------------------------------------------------------------
  31          * Static functions
  32          *------------------------------------------------------------------------*/
  33
  34         /**
  35          * @deprecated use LinksUpdate::queueRecursiveJobs()
  36          */
  37         /**
  38          * static function queueLinksJobs( $titles ) {}
  39          */
  40
  41         /**
  42          * Pop a job off the front of the queue
  43          * @static
  44          * @param $offset Number of jobs to skip
  45          * @return Job or false if there's no jobs
  46          */
  47         static function pop($offset=0) {
  48                 wfProfileIn( __METHOD__ );
  49
  50                 $dbr = wfGetDB( DB_SLAVE );
  51
  52                 /* Get a job from the slave, start with an offset,
  53                         scan full set afterwards, avoid hitting purged rows
  54
  55                         NB: If random fetch previously was used, offset
  56                                 will always be ahead of few entries
  57                 */
  58
  59                 $row = $dbr->selectRow( 'job', '*', "job_id >= ${offset}", __METHOD__,
  60                         array( 'ORDER BY' => 'job_id', 'LIMIT' => 1 ));
  61
  62                 // Refetching without offset is needed as some of job IDs could have had delayed commits
  63                 // and have lower IDs than jobs already executed, blame concurrency :)
  64                 //
  65                 if ( $row === false) {
  66                         if ($offset!=0)
  67                                 $row = $dbr->selectRow( 'job', '*', '', __METHOD__,
  68                                         array( 'ORDER BY' => 'job_id', 'LIMIT' => 1 ));
  69
  70                         if ($row === false ) {
  71                                 wfProfileOut( __METHOD__ );
  72                                 return false;
  73                         }
  74                 }
  75                 $offset = $row->job_id;
  76
  77                 // Try to delete it from the master
  78                 $dbw = wfGetDB( DB_MASTER );
  79                 $dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
  80                 $affected = $dbw->affectedRows();
  81                 $dbw->immediateCommit();
  82
  83                 if ( !$affected ) {
  84                         // Failed, someone else beat us to it
  85                         // Try getting a random row
  86                         $row = $dbw->selectRow( 'job', array( 'MIN(job_id) as minjob',
  87                                 'MAX(job_id) as maxjob' ), "job_id >= $offset", __METHOD__ );
  88                         if ( $row === false || is_null( $row->minjob ) || is_null( $row->maxjob ) ) {
  89                                 // No jobs to get
  90                                 wfProfileOut( __METHOD__ );
  91                                 return false;
  92                         }
  93                         // Get the random row
  94                         $row = $dbw->selectRow( 'job', '*',
  95                                 'job_id >= ' . mt_rand( $row->minjob, $row->maxjob ),   __METHOD__ );
  96                         if ( $row === false ) {
  97                                 // Random job gone before we got the chance to select it
  98                                 // Give up
  99                                 wfProfileOut( __METHOD__ );
 100                                 return false;
 101                         }
 102                         // Delete the random row
 103                         $dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
 104                         $affected = $dbw->affectedRows();
 105                         $dbw->immediateCommit();
 106
 107                         if ( !$affected ) {
 108                                 // Random job gone before we exclusively deleted it
 109                                 // Give up
 110                                 wfProfileOut( __METHOD__ );
 111                                 return false;
 112                         }
 113                 }
 114
 115                 // If execution got to here, there's a row in $row that has been deleted from the database
 116                 // by this thread. Hence the concurrent pop was successful.
 117                 $namespace = $row->job_namespace;
 118                 $dbkey = $row->job_title;
 119                 $title = Title::makeTitleSafe( $namespace, $dbkey );
 120                 $job = Job::factory( $row->job_cmd, $title, Job::extractBlob( $row->job_params ), $row->job_id );
 121
 122                 // Remove any duplicates it may have later in the queue
 123                 $dbw->delete( 'job', $job->insertFields(), __METHOD__ );
 124
 125                 wfProfileOut( __METHOD__ );
 126                 return $job;
 127         }
 128
 129         /**
 130          * Create an object of a subclass
 131          */
 132         static function factory( $command, $title, $params = false, $id = 0 ) {
 133                 switch ( $command ) {
 134                         case 'refreshLinks':
 135                                 return new RefreshLinksJob( $title, $params, $id );
 136                         case 'htmlCacheUpdate':
 137                         case 'html_cache_update': # BC
 138                                 return new HTMLCacheUpdateJob( $title, $params['table'], $params['start'], $params['end'], $id );
 139                         case 'sendMail':
 140                                 return new EmaillingJob($params);
 141                         default:
 142                                 throw new MWException( "Invalid job command \"$command\"" );
 143                 }
 144         }
 145
 146         static function makeBlob( $params ) {
 147                 if ( $params !== false ) {
 148                         return serialize( $params );
 149                 } else {
 150                         return '';
 151                 }
 152         }
 153
 154         static function extractBlob( $blob ) {
 155                 if ( (string)$blob !== '' ) {
 156                         return unserialize( $blob );
 157                 } else {
 158                         return false;
 159                 }
 160         }
 161
 162         /**
 163          * Batch-insert a group of jobs into the queue.
 164          * This will be wrapped in a transaction with a forced commit.
 165          *
 166          * This may add duplicate at insert time, but they will be
 167          * removed later on, when the first one is popped.
 168          *
 169          * @param $jobs array of Job objects
 170          */
 171         static function batchInsert( $jobs ) {
 172                 if( count( $jobs ) ) {
 173                         $dbw = wfGetDB( DB_MASTER );
 174                         $dbw->begin();
 175                         foreach( $jobs as $job ) {
 176                                 $rows[] = $job->insertFields();
 177                         }
 178                         $dbw->insert( 'job', $rows, __METHOD__, 'IGNORE' );
 179                         $dbw->commit();
 180                 }
 181         }
 182
 183         /*-------------------------------------------------------------------------
 184          * Non-static functions
 185          *------------------------------------------------------------------------*/
 186
 187         function __construct( $command, $title, $params = false, $id = 0 ) {
 188                 $this->command = $command;
 189                 $this->title = $title;
 190                 $this->params = $params;
 191                 $this->id = $id;
 192
 193                 // A bit of premature generalisation
 194                 // Oh well, the whole class is premature generalisation really
 195                 $this->removeDuplicates = true;
 196         }
 197
 198         /**
 199          * Insert a single job into the queue.
 200          */
 201         function insert() {
 202                 $fields = $this->insertFields();
 203
 204                 $dbw = wfGetDB( DB_MASTER );
 205
 206                 if ( $this->removeDuplicates ) {
 207                         $res = $dbw->select( 'job', array( '1' ), $fields, __METHOD__ );
 208                         if ( $dbw->numRows( $res ) ) {
 209                                 return;
 210                         }
 211                 }
 212                 $fields['job_id'] = $dbw->nextSequenceValue( 'job_job_id_seq' );
 213                 $dbw->insert( 'job', $fields, __METHOD__ );
 214         }
 215
 216         protected function insertFields() {
 217                 return array(
 218                         'job_cmd' => $this->command,
 219                         'job_namespace' => $this->title->getNamespace(),
 220                         'job_title' => $this->title->getDBkey(),
 221                         'job_params' => Job::makeBlob( $this->params )
 222                 );
 223         }
 224
 225         function toString() {
 226                 $paramString = '';
 227                 if ( $this->params ) {
 228                         foreach ( $this->params as $key => $value ) {
 229                                 if ( $paramString != '' ) {
 230                                         $paramString .= ' ';
 231                                 }
 232                                 $paramString .= "$key=$value";
 233                         }
 234                 }
 235
 236                 if ( is_object( $this->title ) ) {
 237                         $s = "{$this->command} " . $this->title->getPrefixedDBkey();
 238                         if ( $paramString !== '' ) {
 239                                 $s .= ' ' . $paramString;
 240                         }
 241                         return $s;
 242                 } else {
 243                         return "{$this->command} $paramString";
 244                 }
 245         }
 246
 247         function getLastError() {
 248                 return $this->error;
 249         }
 250 }
 251
 252
 253 /**
 254  * Background job to update links for a given title.
 255  */
 256 class RefreshLinksJob extends Job {
 257         function __construct( $title, $params = '', $id = 0 ) {
 258                 parent::__construct( 'refreshLinks', $title, $params, $id );
 259         }
 260
 261         /**
 262          * Run a refreshLinks job
 263          * @return boolean success
 264          */
 265         function run() {
 266                 global $wgParser;
 267                 wfProfileIn( __METHOD__ );
 268
 269                 $linkCache =& LinkCache::singleton();
 270                 $linkCache->clear();
 271
 272                 if ( is_null( $this->title ) ) {
 273                         $this->error = "refreshLinks: Invalid title";
 274                         wfProfileOut( __METHOD__ );
 275                         return false;
 276                 }
 277
 278                 $revision = Revision::newFromTitle( $this->title );
 279                 if ( !$revision ) {
 280                         $this->error = 'refreshLinks: Article not found "' . $this->title->getPrefixedDBkey() . '"';
 281                         wfProfileOut( __METHOD__ );
 282                         return false;
 283                 }
 284
 285                 wfProfileIn( __METHOD__.'-parse' );
 286                 $options = new ParserOptions;
 287                 $parserOutput = $wgParser->parse( $revision->getText(), $this->title, $options, true, true, $revision->getId() );
 288                 wfProfileOut( __METHOD__.'-parse' );
 289                 wfProfileIn( __METHOD__.'-update' );
 290                 $update = new LinksUpdate( $this->title, $parserOutput, false );
 291                 $update->doUpdate();
 292                 wfProfileOut( __METHOD__.'-update' );
 293                 wfProfileOut( __METHOD__ );
 294                 return true;
 295         }
 296 }
 297
 298 class EmaillingJob extends Job {
 299         function __construct($params) {
 300                 parent::__construct('sendMail', Title::newMainPage(), $params);
 301         }
 302
 303         function run() {
 304                 userMailer($this->params['to'], $this->params['from'], $this->params['subj'],
 305                                 $this->params['body'], $this->params['replyto']);
 306         }
 307 }
 308
 309 ?>