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