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 class Job {
   8         private
   9                 $command,
  10                 $title,
  11                 $params,
  12                 $id,
  13                 $removeDuplicates,
  14                 $error;
  15
  16         /*-------------------------------------------------------------------------
  17          * Static functions
  18          *------------------------------------------------------------------------*/
  19         /**
  20          * Add an array of refreshLinks jobs to the queue
  21          * @param array $titles Array of title objects.
  22          * @static
  23          */
  24         function queueLinksJobs( $titles ) {
  25                 $fname = 'Job::queueLinksJobs';
  26                 wfProfileIn( $fname );
  27                 foreach ( $titles as $title ) {
  28                         $job = new Job( 'refreshLinks', $title );
  29                         $job->insert();
  30                 }
  31                 wfProfileOut( $fname );
  32         }
  33
  34         /**
  35          * Pop a job off the front of the queue
  36          * @static
  37          * @return Job or false if there's no jobs
  38          */
  39         function pop() {
  40                 $fname = 'Job::pop';
  41                 wfProfileIn( $fname );
  42
  43                 $dbr =& wfGetDB( DB_SLAVE );
  44
  45                 // Get a job from the slave
  46                 $row = $dbr->selectRow( 'job', '*', '', $fname,
  47                         array( 'ORDER BY' => 'job_id', 'LIMIT' => 1 )
  48                 );
  49
  50                 if ( $row === false ) {
  51                         wfProfileOut( $fname );
  52                         return false;
  53                 }
  54
  55                 // Try to delete it from the master
  56                 $dbw =& wfGetDB( DB_MASTER );
  57                 $dbw->delete( 'job', array( 'job_id' => $row->job_id ), $fname );
  58                 $affected = $dbw->affectedRows();
  59                 $dbw->immediateCommit();
  60
  61                 if ( !$affected ) {
  62                         // Failed, someone else beat us to it
  63                         // Try getting a random row
  64                         $row = $dbw->selectRow( 'job', array( 'MIN(job_id) as minjob',
  65                                 'MAX(job_id) as maxjob' ), '', $fname );
  66                         if ( $row === false || is_null( $row->minjob ) || is_null( $row->maxjob ) ) {
  67                                 // No jobs to get
  68                                 wfProfileOut( $fname );
  69                                 return false;
  70                         }
  71                         // Get the random row
  72                         $row = $dbw->selectRow( 'job', '*',
  73                                 array( 'job_id' => mt_rand( $row->minjob, $row->maxjob ) ),     $fname );
  74                         if ( $row === false ) {
  75                                 // Random job gone before we got the chance to select it
  76                                 // Give up
  77                                 wfProfileOut( $fname );
  78                                 return false;
  79                         }
  80                         // Delete the random row
  81                         $dbw->delete( 'job', array( 'job_id' => $row->job_id ), $fname );
  82                         $affected = $dbw->affectedRows();
  83                         $dbw->immediateCommit();
  84
  85                         if ( !$affected ) {
  86                                 // Random job gone before we exclusively deleted it
  87                                 // Give up
  88                                 wfProfileOut( $fname );
  89                                 return false;
  90                         }
  91                 }
  92
  93                 // If execution got to here, there's a row in $row that has been deleted from the database
  94                 // by this thread. Hence the concurrent pop was successful.
  95                 $namespace = $row->job_namespace;
  96                 $dbkey = $row->job_title;
  97                 $title = Title::makeTitleSafe( $namespace, $dbkey );
  98                 $job = new Job( $row->job_cmd, $title, $row->job_params, $row->job_id );
  99                 wfProfileOut( $fname );
 100                 return $job;
 101         }
 102
 103         /*-------------------------------------------------------------------------
 104          * Non-static functions
 105          *------------------------------------------------------------------------*/
 106
 107         function Job( $command, $title, $params = '', $id = 0 ) {
 108                 $this->command = $command;
 109                 $this->title = $title;
 110                 $this->params = $params;
 111                 $this->id = $id;
 112
 113                 // A bit of premature generalisation
 114                 // Oh well, the whole class is premature generalisation really
 115                 $this->removeDuplicates = true;
 116         }
 117
 118         function insert() {
 119                 $fname = 'Job::insert';
 120
 121                 $fields = array(
 122                         'job_cmd' => $this->command,
 123                         'job_namespace' => $this->title->getNamespace(),
 124                         'job_title' => $this->title->getDBkey(),
 125                         'job_params' => $this->params
 126                 );
 127
 128                 $dbw =& wfGetDB( DB_MASTER );
 129
 130                 if ( $this->removeDuplicates ) {
 131                         $res = $dbw->select( 'job', array( '1' ), $fields, $fname );
 132                         if ( $dbw->numRows( $res ) ) {
 133                                 return;
 134                         }
 135                 }
 136                 $fields['job_id'] = $dbw->nextSequenceValue( 'job_job_id_seq' );
 137                 $dbw->insert( 'job', $fields, $fname );
 138         }
 139
 140         /**
 141          * Run the job
 142          * @return boolean success
 143          */
 144         function run() {
 145                 $fname = 'Job::run';
 146                 wfProfileIn( $fname );
 147                 switch ( $this->command ) {
 148                         case 'refreshLinks':
 149                                 $retval = $this->refreshLinks();
 150                                 break;
 151                         default:
 152                                 $this->error = "Invalid job type {$this->command}, ignoring";
 153                                 wfDebug( $this->error . "\n" );
 154                                 $retval = false;
 155                 }
 156                 wfProfileOut( $fname );
 157                 return $retval;
 158         }
 159
 160         /**
 161          * Run a refreshLinks job
 162          * @return boolean success
 163          */
 164         function refreshLinks() {
 165                 global $wgParser;
 166                 $fname = 'Job::refreshLinks';
 167                 wfProfileIn( $fname );
 168
 169                 # FIXME: $dbw never used.
 170                 $dbw =& wfGetDB( DB_MASTER );
 171
 172                 $linkCache =& LinkCache::singleton();
 173                 $linkCache->clear();
 174
 175                 if ( is_null( $this->title ) ) {
 176                         $this->error = "refreshLinks: Invalid title";
 177                         wfProfileOut( $fname );
 178                         return false;
 179                 }
 180
 181                 $revision = Revision::newFromTitle( $this->title );
 182                 if ( !$revision ) {
 183                         $this->error = 'refreshLinks: Article not found "' . $this->title->getPrefixedDBkey() . '"';
 184                         wfProfileOut( $fname );
 185                         return false;
 186                 }
 187
 188                 wfProfileIn( "$fname-parse" );
 189                 $options = new ParserOptions;
 190                 $parserOutput = $wgParser->parse( $revision->getText(), $this->title, $options, true, true, $revision->getId() );
 191                 wfProfileOut( "$fname-parse" );
 192                 wfProfileIn( "$fname-update" );
 193                 $update = new LinksUpdate( $this->title, $parserOutput, false );
 194                 $update->doUpdate();
 195                 wfProfileOut( "$fname-update" );
 196                 wfProfileOut( $fname );
 197                 return true;
 198         }
 199
 200         function toString() {
 201                 if ( is_object( $this->title ) ) {
 202                         $s = "{$this->command} " . $this->title->getPrefixedDBkey();
 203                         if ( $this->params !== '' ) {
 204                                 $s .= ', ' . $this->params;
 205                         }
 206                         return $s;
 207                 } else {
 208                         return "{$this->command} {$this->params}";
 209                 }
 210         }
 211
 212         function getLastError() {
 213                 return $this->error;
 214         }
 215 }
 216 ?>