<?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, $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";
- $sql = $db->limitResult($sql, 1, 0);
- $res = $db->query( $sql, $fname );
-
- $title = null;
- if( $s = $db->fetchObject( $res ) ) {
- $title =& Title::makeTitle( $namespace, $s->page_title );
+ public function getNamespace() {
+ return $this->namespace;
}
- if( is_null( $title ) ) {
- # That's not supposed to happen :)
- $title = Title::newFromText( wfMsg( 'mainpage' ) );
+
+ public function setNamespace ( $ns ) {
+ if( $ns < NS_MAIN ) $ns = NS_MAIN;
+ $this->namespace = $ns;
+ }
+
+ // 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 ) );
}
- $wgOut->reportTime(); # for logfile
- $wgOut->redirect( $title->getFullUrl() );
-}
-?>
+
+ /**
+ * 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 );
+ }
+}