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 && $offset != 0 ) {
  51                         $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
  61                 /* Still avoid scanning purged rows */
  62                 $offset = $row->job_id;
  63
  64                 // Try to delete it from the master
  65                 $dbw = wfGetDB( DB_MASTER );
  66                 $dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
  67                 $affected = $dbw->affectedRows();
  68                 $dbw->immediateCommit();
  69
  70                 if ( !$affected ) {
  71                         // Failed, someone else beat us to it
  72                         // Try getting a random row
  73                         $row = $dbw->selectRow( 'job', array( 'MIN(job_id) as minjob',
  74                                 'MAX(job_id) as maxjob' ), "job_id >= $offset", __METHOD__ );
  75                         if ( $row === false || is_null( $row->minjob ) || is_null( $row->maxjob ) ) {
  76                                 // No jobs to get
  77                                 wfProfileOut( __METHOD__ );
  78                                 return false;
  79                         }
  80                         // Get the random row
  81                         $row = $dbw->selectRow( 'job', '*',
  82                                 'job_id >= ' . mt_rand( $row->minjob, $row->maxjob ),   __METHOD__ );
  83                         if ( $row === false ) {
  84                                 // Random job gone before we got the chance to select it
  85                                 // Give up
  86                                 wfProfileOut( __METHOD__ );
  87                                 return false;
  88                         }
  89                         // Delete the random row
  90                         $dbw->delete( 'job', array( 'job_id' => $row->job_id ), __METHOD__ );
  91                         $affected = $dbw->affectedRows();
  92                         $dbw->immediateCommit();
  93
  94                         if ( !$affected ) {
  95                                 // Random job gone before we exclusively deleted it
  96                                 // Give up
  97                                 wfProfileOut( __METHOD__ );
  98                                 return false;
  99                         }
 100                 }
 101
 102                 // If execution got to here, there's a row in $row that has been deleted from the database
 103                 // by this thread. Hence the concurrent pop was successful.
 104                 $namespace = $row->job_namespace;
 105                 $dbkey = $row->job_title;
 106                 $title = Title::makeTitleSafe( $namespace, $dbkey );
 107                 $job = Job::factory( $row->job_cmd, $title, Job::extractBlob( $row->job_params ), $row->job_id );
 108
 109                 // Remove any duplicates it may have later in the queue
 110                 $dbw->delete( 'job', $job->insertFields(), __METHOD__ );
 111
 112                 wfProfileOut( __METHOD__ );
 113                 return $job;
 114         }
 115
 116         /**
 117          * Create an object of a subclass
 118          */
 119         static function factory( $command, $title, $params = false, $id = 0 ) {
 120                 switch ( $command ) {
 121                         case 'refreshLinks':
 122                                 return new RefreshLinksJob( $title, $params, $id );
 123                         case 'htmlCacheUpdate':
 124                         case 'html_cache_update': # BC
 125                                 return new HTMLCacheUpdateJob( $title, $params['table'], $params['start'], $params['end'], $id );
 126                         default:
 127                                 throw new MWException( "Invalid job command \"$command\"" );
 128                 }
 129         }
 130
 131         static function makeBlob( $params ) {
 132                 if ( $params !== false ) {
 133                         return serialize( $params );
 134                 } else {
 135                         return '';
 136                 }
 137         }
 138
 139         static function extractBlob( $blob ) {
 140                 if ( (string)$blob !== '' ) {
 141                         return unserialize( $blob );
 142                 } else {
 143                         return false;
 144                 }
 145         }
 146
 147         /*-------------------------------------------------------------------------
 148          * Non-static functions
 149          *------------------------------------------------------------------------*/
 150
 151         function __construct( $command, $title, $params = false, $id = 0 ) {
 152                 $this->command = $command;
 153                 $this->title = $title;
 154                 $this->params = $params;
 155                 $this->id = $id;
 156
 157                 // A bit of premature generalisation
 158                 // Oh well, the whole class is premature generalisation really
 159                 $this->removeDuplicates = true;
 160         }
 161
 162         /**
 163          * Insert a single job into the queue.
 164          */
 165         function insert() {
 166                 $fields = $this->insertFields();
 167
 168                 $dbw = wfGetDB( DB_MASTER );
 169
 170                 if ( $this->removeDuplicates ) {
 171                         $res = $dbw->select( 'job', array( '1' ), $fields, __METHOD__ );
 172                         if ( $dbw->numRows( $res ) ) {
 173                                 return;
 174                         }
 175                 }
 176                 $fields['job_id'] = $dbw->nextSequenceValue( 'job_job_id_seq' );
 177                 $dbw->insert( 'job', $fields, __METHOD__ );
 178         }
 179
 180         protected function insertFields() {
 181                 return array(
 182                         'job_cmd' => $this->command,
 183                         'job_namespace' => $this->title->getNamespace(),
 184                         'job_title' => $this->title->getDBkey(),
 185                         'job_params' => Job::makeBlob( $this->params )
 186                 );
 187         }
 188
 189         /**
 190          * Batch-insert a group of jobs into the queue.
 191          * This will be wrapped in a transaction with a forced commit.
 192          *
 193          * This may add duplicate at insert time, but they will be
 194          * removed later on, when the first one is popped.
 195          *
 196          * @param $jobs array of Job objects
 197          */
 198         static function batchInsert( $jobs ) {
 199                 if( count( $jobs ) ) {
 200                         $dbw = wfGetDB( DB_MASTER );
 201                         $dbw->begin();
 202                         foreach( $jobs as $job ) {
 203                                 $rows[] = $job->insertFields();
 204                         }
 205                         $dbw->insert( 'job', $rows, __METHOD__, 'IGNORE' );
 206                         $dbw->commit();
 207                 }
 208         }
 209
 210         /**
 211          * Run the job
 212          * @return boolean success
 213          */
 214         abstract function run();
 215
 216         function toString() {
 217                 $paramString = '';
 218                 if ( $this->params ) {
 219                         foreach ( $this->params as $key => $value ) {
 220                                 if ( $paramString != '' ) {
 221                                         $paramString .= ' ';
 222                                 }
 223                                 $paramString .= "$key=$value";
 224                         }
 225                 }
 226
 227                 if ( is_object( $this->title ) ) {
 228                         $s = "{$this->command} " . $this->title->getPrefixedDBkey();
 229                         if ( $paramString !== '' ) {
 230                                 $s .= ' ' . $paramString;
 231                         }
 232                         return $s;
 233                 } else {
 234                         return "{$this->command} $paramString";
 235                 }
 236         }
 237
 238         function getLastError() {
 239                 return $this->error;
 240         }
 241 }
 242
 243 class RefreshLinksJob extends Job {
 244         function __construct( $title, $params = '', $id = 0 ) {
 245                 parent::__construct( 'refreshLinks', $title, $params, $id );
 246         }
 247
 248         /**
 249          * Run a refreshLinks job
 250          * @return boolean success
 251          */
 252         function run() {
 253                 global $wgParser;
 254                 wfProfileIn( __METHOD__ );
 255
 256                 $linkCache =& LinkCache::singleton();
 257                 $linkCache->clear();
 258
 259                 if ( is_null( $this->title ) ) {
 260                         $this->error = "refreshLinks: Invalid title";
 261                         wfProfileOut( __METHOD__ );
 262                         return false;
 263                 }
 264
 265                 $revision = Revision::newFromTitle( $this->title );
 266                 if ( !$revision ) {
 267                         $this->error = 'refreshLinks: Article not found "' . $this->title->getPrefixedDBkey() . '"';
 268                         wfProfileOut( __METHOD__ );
 269                         return false;
 270                 }
 271
 272                 wfProfileIn( __METHOD__.'-parse' );
 273                 $options = new ParserOptions;
 274                 $parserOutput = $wgParser->parse( $revision->getText(), $this->title, $options, true, true, $revision->getId() );
 275                 wfProfileOut( __METHOD__.'-parse' );
 276                 wfProfileIn( __METHOD__.'-update' );
 277                 $update = new LinksUpdate( $this->title, $parserOutput, false );
 278                 $update->doUpdate();
 279                 wfProfileOut( __METHOD__.'-update' );
 280                 wfProfileOut( __METHOD__ );
 281                 return true;
 282         }
 283 }
 284
 285 ?>