includes/SpecialRandompage.php

   1 <?php
   2 /**
   3  * @package MediaWiki
   4  * @subpackage SpecialPage
   5  */
   6
   7 /**
   8  * Constructor
   9  *
  10  * @param string $par the namespace to get a random page from (default NS_MAIN),
  11  *               used as e.g. Special:Randompage/Category
  12  */
  13 function wfSpecialRandompage( $par = NS_MAIN ) {
  14         global $wgOut, $wgTitle, $wgArticle, $wgExtraRandompageSQL, $wgContLang;
  15         $fname = 'wfSpecialRandompage';
  16
  17         # Determine the namespace to get a random page from.
  18         $namespace = $wgContLang->getNsIndex($par);
  19         if ($namespace === false || $namespace < NS_MAIN) {
  20                 $namespace = NS_MAIN;
  21         }
  22
  23         # NOTE! We use a literal constant in the SQL instead of the RAND()
  24         # function because RAND() will return a different value for every row
  25         # in the table. That's both very slow and returns results heavily
  26         # biased towards low values, as rows later in the table will likely
  27         # never be reached for comparison.
  28         #
  29         # Using a literal constant means the whole thing gets optimized on
  30         # the index, and the comparison is both fast and fair.
  31
  32         # interpolation and sprintf() can muck up with locale-specific decimal separator
  33         $randstr = wfRandom();
  34
  35         $db =& wfGetDB( DB_SLAVE );
  36         $use_index = $db->useIndexClause( 'page_random' );
  37         $page = $db->tableName( 'page' );
  38
  39         $extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : '';
  40         $sql = "SELECT page_id,page_title
  41                 FROM $page $use_index
  42                 WHERE page_namespace=$namespace AND page_is_redirect=0 $extra
  43                 AND page_random>$randstr
  44                 ORDER BY page_random
  45                 LIMIT 1";
  46         $res = $db->query( $sql, $fname );
  47
  48         $title = null;
  49         if( $s = $db->fetchObject( $res ) ) {
  50                 $title =& Title::makeTitle( $namespace, $s->page_title );
  51         }
  52         if( is_null( $title ) ) {
  53                 # That's not supposed to happen :)
  54                 $title =& Title::newFromText( wfMsg( 'mainpage' ) );
  55         }
  56         $wgOut->reportTime(); # for logfile
  57         $wgOut->redirect( $title->getFullUrl() );
  58 }
  59
  60 ?>