includes/SpecialRandompage.php

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