Making INNER JOIN implicit

[lhc/web/wiklou.git] / includes / SpecialRandompage.php

diff --git a/includes/SpecialRandompage.php b/includes/SpecialRandompage.php
index 82d580c..1ba8e98 100644 (file)
--- a/includes/SpecialRandompage.php
+++ b/includes/SpecialRandompage.php
@@ -1,60 +1,106 @@
 <?php
+
 /**
- * @package MediaWiki
- * @subpackage SpecialPage
+ * Special page to direct the user to a random page
+ *
+ * @addtogroup SpecialPage
+ * @author Rob Church <robchur@gmail.com>, Ilmari Karonen
+ * @license GNU General Public Licence 2.0 or later
  */
 
 /**
- * Constructor
+ * Special page to direct the user to a random page
  *
- * @param string $par the namespace to get a random page from (default NS_MAIN), 
- *               used as e.g. Special:Randompage/Category
+ * @addtogroup SpecialPage
  */
-function wfSpecialRandompage( $par = NS_MAIN ) {
-       global $wgOut, $wgTitle, $wgArticle, $wgExtraRandompageSQL, $wgContLang;
-       $fname = 'wfSpecialRandompage';
-
-       # Determine the namespace to get a random page from.
-       $namespace = $wgContLang->getNsIndex($par);
-       if ($namespace === false || $namespace < NS_MAIN) {
-               $namespace = NS_MAIN;
+class RandomPage extends SpecialPage {
+       private $namespace = NS_MAIN;  // namespace to select pages from
+
+       function __construct( $name = 'Randompage' ){
+               parent::__construct( $name );
        }
-       
-       # NOTE! We use a literal constant in the SQL instead of the RAND()
-       # function because RAND() will return a different value for every row
-       # in the table. That's both very slow and returns results heavily
-       # biased towards low values, as rows later in the table will likely
-       # never be reached for comparison.
-       #
-       # Using a literal constant means the whole thing gets optimized on
-       # the index, and the comparison is both fast and fair.
-       
-       # interpolation and sprintf() can muck up with locale-specific decimal separator
-       $randstr = wfRandom();
-       
-       $db =& wfGetDB( DB_SLAVE );
-       $use_index = $db->useIndexClause( 'page_random' );
-       $page = $db->tableName( 'page' );
-
-       $extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : '';
-       $sql = "SELECT page_id,page_title
-               FROM $page $use_index
-               WHERE page_namespace=$namespace AND page_is_redirect=0 $extra
-               AND page_random>$randstr
-               ORDER BY page_random
-               LIMIT 1";
-       $res = $db->query( $sql, $fname );
-       
-       $title = null;
-       if( $s = $db->fetchObject( $res ) ) {
-               $title =& Title::makeTitle( $namespace, $s->page_title );
-       }       
-       if( is_null( $title ) ) {
-               # That's not supposed to happen :)
-               $title = Title::newFromText( wfMsg( 'mainpage' ) );
+
+       public function getNamespace() {
+               return $this->namespace;
+       }
+
+       public function setNamespace ( $ns ) {
+               if( $ns < NS_MAIN ) $ns = NS_MAIN;
+               $this->namespace = $ns;
        }
-       $wgOut->reportTime(); # for logfile
-       $wgOut->redirect( $title->getFullUrl() );
-}
 
-?>
+       // select redirects instead of normal pages?
+       // Overriden by SpecialRandomredirect
+       public function isRedirect(){
+               return false;
+       }
+
+       public function execute( $par ) {
+               global $wgOut, $wgContLang;
+
+               if ($par)
+                       $this->setNamespace( $wgContLang->getNsIndex( $par ) );
+
+               $title = $this->getRandomTitle();
+
+               if( is_null( $title ) ) {
+                       $this->setHeaders();
+                       $wgOut->addWikiMsg( strtolower( $this->mName ) . '-nopages' );
+                       return;
+               }
+
+               $query = $this->isRedirect() ? 'redirect=no' : '';
+               $wgOut->redirect( $title->getFullUrl( $query ) );
+       }
+
+
+       /**
+        * Choose a random title.
+        * @return Title object (or null if nothing to choose from)
+        */
+       public function getRandomTitle() {
+               $randstr = wfRandom();
+               $row = $this->selectRandomPageFromDB( $randstr );
+
+               /* If we picked a value that was higher than any in
+                * the DB, wrap around and select the page with the
+                * lowest value instead!  One might think this would
+                * skew the distribution, but in fact it won't cause
+                * any more bias than what the page_random scheme
+                * causes anyway.  Trust me, I'm a mathematician. :)
+                */
+               if( !$row )
+                       $row = $this->selectRandomPageFromDB( "0" );
+
+               if( $row )
+                       return Title::makeTitleSafe( $this->namespace, $row->page_title );
+               else
+                       return null;
+       }
+
+       private function selectRandomPageFromDB( $randstr ) {
+               global $wgExtraRandompageSQL;
+               $fname = 'RandomPage::selectRandomPageFromDB';
+
+               $dbr = wfGetDB( DB_SLAVE );
+
+               $use_index = $dbr->useIndexClause( 'page_random' );
+               $page = $dbr->tableName( 'page' );
+
+               $ns = (int) $this->namespace;
+               $redirect = $this->isRedirect() ? 1 : 0;
+
+               $extra = $wgExtraRandompageSQL ? "AND ($wgExtraRandompageSQL)" : "";
+               $sql = "SELECT page_title
+                       FROM $page $use_index
+                       WHERE page_namespace = $ns
+                       AND page_is_redirect = $redirect
+                       AND page_random >= $randstr
+                       $extra
+                       ORDER BY page_random";
+
+               $sql = $dbr->limitResult( $sql, 1, 0 );
+               $res = $dbr->query( $sql, $fname );
+               return $dbr->fetchObject( $res );
+       }
+}