includes/SpecialRandompage.php

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