Extension:ParserCacheControl/Code

<?php
/*
 * ParserCacheControl.php
 * 
 * MediaWiki extension
 * @author: Jean-Lou Dupont (http://www.bluecortex.com)
 *
 * Purpose: Controls the Parser Cache without having to
 *          patch a Mediawiki installation.
 *
 * Benefit: Simplify development of complex dynamical extensions whilst
 *          preserving the advantages of parser output caching. 
 *
 * Features:
 * *********
 * - Parser Cache disabling upon article updating/creation (default behavior)
 *
 * DEPENDANCIES:
 * - ExtensionClass (>v1.3)
 *
 * Tested Compatibility:  MW 1.8.2, 1.9.3
 *
 * HISTORY:
 * -- Version 1.0
 */
 
class ParserCacheControl extends ExtensionClass
{
        const thisName = 'ParserCacheControl';
        const thisType = 'other';  // must use this type in order to display useful info in Special:Version
 
        // parser cache control parameter
        // This property is public and thus can be manipulated
        // by other extensions
        var $disableParserCache;
 
        public static function &singleton( )
        { return parent::singleton( ); }
 
        // Our class defines magic words: tell it to our helper class.
        public function ParserCacheControl() 
        {
                parent::__construct( );
                global $wgExtensionCredits, $wgParserCacheType, $wgEnableParserCache, $parserMemc;
 
                $pct = array( CACHE_NONE => "CACHE_NONE", CACHE_ANYTHING => "CACHE_ANYTHING",
                                        CACHE_MEMCACHED => "CACHE_MEMCACHED", CACHE_DB => "CACHE_DB",
                                        CACHE_ACCEL => "CACHE_ACCEL", CACHE_DBA => "CACHE_DBA",
                );
 
                // Let's provide some helpful information in the
                // 'Special:Version' page.
                $wgExtensionCredits[self::thisType][] = array( 
                        'name'    => self::thisName, 
                        'version' => '$LastChangedRevision: 202 $',
                        'author'  => 'Jean-Lou Dupont', 
                        'url'     => 'http://www.bluecortex.com',
                        'description' => "Parser Cache (\$wgEnableParserCache) is currently <b>".($wgEnableParserCache ? "enabled":"disabled").
                                         "</b> whilst \$wgParserCacheType is set to <b>".$pct[$wgParserCacheType]."</b>",
                );
 
                // by default, parser cache is now disabled
                // when Article::editupdates is performed.
                $this->disableParserCache = true;
        }
        public function setup()
        {
                parent::setup();
 
                global $wgHooks;
                $wgHooks['ArticleSave'][] =                  array( &$this, 'hArticleSave' );      
        }
        public function hUpdateExtensionCredits( &$sp, &$extensionTypes )
        {
                global $wgExtensionCredits, $parserMemc;
 
                $pmc = get_class( $parserMemc );
 
                foreach ( $wgExtensionCredits[self::thisType] as $index => &$el )
                {
                        if ($el['name']==self::thisName)
                                $el['description'].=" and \$parserMemc is set to a <b>{$pmc}</b> object";       
                }
 
                return true; // continue hook-chain.
        }
        public function hArticleSave( &$article, &$user, &$text, &$summary, $minor, $watch, $sectionanchor, &$flags )
        {
                if (!$this->disableParserCache)
                        return true;
 
                global $wgParserCacheType;
                // disable the parser cache for this transaction.
                // The hack below will affect the method Article::editUpdates
                // into not saving the current article to a potential real cache.
                // BUT, once the article is viewed, the article will then be stored in the real cache.        
                $wgParserCacheType = CACHE_NONE;
                $apc =& wfGetParserCacheStorage();
 
                $pc = & ParserCache::singleton();
                $pc->mMemc = $apc;
 
                return true;
        }
 
} // end class definition.
 
ParserCacheControl::singleton();