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