LinkCache.php

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<?php
# Cache for article titles (prefixed DB keys) and ids linked from one source

# These are used in incrementalSetup()
define ('LINKCACHE_GOOD', 0);
define ('LINKCACHE_BAD', 1);
define ('LINKCACHE_IMAGE', 2);

class LinkCache {       
        // Increment $mClassVer whenever old serialized versions of this class
        // becomes incompatible with the new version.
        /* private */ var $mClassVer = 2;

        /* private */ var $mGoodLinks, $mBadLinks, $mActive;
        /* private */ var $mImageLinks, $mCategoryLinks;
        /* private */ var $mPreFilled, $mOldGoodLinks, $mOldBadLinks;
        
        /* private */ function getKey( $title ) {
                global $wgDBname;
                return "$wgDBname:lc:title:$title";
        }
        
        function LinkCache()
        {
                $this->mActive = true;
                $this->mPreFilled = false;
                $this->mGoodLinks = array();
                $this->mBadLinks = array();
                $this->mImageLinks = array();
                $this->mCategoryLinks = array();
                $this->mOldGoodLinks = array();
                $this->mOldBadLinks = array();
        }

        function getGoodLinkID( $title )
        {
                if ( array_key_exists( $title, $this->mGoodLinks ) ) {
                        return $this->mGoodLinks[$title];
                } else {
                        return 0;
                }
        }

        function isBadLink( $title )
        {
                return array_key_exists( $title, $this->mBadLinks ); 
        }

        function addGoodLink( $id, $title )
        {
                if ( $this->mActive ) {
                        $this->mGoodLinks[$title] = $id;
                }
        }

        function addBadLink( $title )
        {
                if ( $this->mActive && ( ! $this->isBadLink( $title ) ) ) {
                        $this->mBadLinks[$title] = 1;
                }
        }

        function addImageLink( $title )
        {
                if ( $this->mActive ) { $this->mImageLinks[$title] = 1; }
        }

        function addImageLinkObj( $nt )
        {
                if ( $this->mActive ) { $this->mImageLinks[$nt->getDBkey()] = 1; }
        }
        
        function addCategoryLink( $title, $sortkey ) {
                if ( $this->mActive ) { $this->mCategoryLinks[$title] = $sortkey; }
        }
        
        function addCategoryLinkObj( &$nt, $sortkey ) {
                $this->addCategoryLink( $nt->getDBkey(), $sortkey );
        }

        function clearBadLink( $title )
        {
                unset( $this->mBadLinks[$title] );
                $this->clearLink( $title );
        }
        
        function clearLink( $title ) 
        {
                global $wgMemc, $wgLinkCacheMemcached;
                if( $wgLinkCacheMemcached )
                        $wgMemc->delete( $this->getKey( $title ) );
        }

        function suspend() { $this->mActive = false; }
        function resume() { $this->mActive = true; }
        function getGoodLinks() { return $this->mGoodLinks; }
        function getBadLinks() { return array_keys( $this->mBadLinks ); }
        function getImageLinks() { return $this->mImageLinks; }
        function getCategoryLinks() { return $this->mCategoryLinks; }

        function addLink( $title )
        {
                $nt = Title::newFromDBkey( $title );
                if( $nt ) {
                        return $this->addLinkObj( $nt );
                } else {
                        return 0;
                }
        }
        
        function addLinkObj( &$nt )
        {
                global $wgMemc, $wgLinkCacheMemcached;
                $title = $nt->getPrefixedDBkey();
                if ( $this->isBadLink( $title ) ) { return 0; }         
                $id = $this->getGoodLinkID( $title );
                if ( 0 != $id ) { return $id; }

                $fname = "LinkCache::addLinkObj";
                wfProfileIn( $fname );

                $ns = $nt->getNamespace();
                $t = $nt->getDBkey();

                if ( "" == $title ) { 
                        wfProfileOut( $fname );
                        return 0; 
                }
                
                $id = NULL;
                if( $wgLinkCacheMemcached )
                        $id = $wgMemc->get( $key = $this->getKey( $title ) );
                if( ! is_integer( $id ) ) {
                        $sql = "SELECT cur_id FROM cur WHERE cur_namespace=" .
                          "{$ns} AND cur_title='" . wfStrencode( $t ) . "'";
                        $res = wfQuery( $sql, DB_READ, "LinkCache::addLink" );

                        if ( 0 == wfNumRows( $res ) ) {
                                $id = 0;
                        } else {
                                $s = wfFetchObject( $res );
                                $id = $s->cur_id;
                        }
                        if( $wgLinkCacheMemcached )
                                $wgMemc->add( $key, $id, 3600*24 );
                }
                
                if ( 0 == $id ) { $this->addBadLink( $title ); }
                else { $this->addGoodLink( $id, $title ); }
                wfProfileOut( $fname );
                return $id;
        }

        function preFill( &$fromtitle )
        {
                global $wgEnablePersistentLC;

                $fname = "LinkCache::preFill";
                wfProfileIn( $fname );
                # Note -- $fromtitle is a Title *object*

                $this->suspend();
                $id = $fromtitle->getArticleID();
                $this->resume();
                
                if( $id == 0 ) {
                        wfDebug( "$fname - got id 0 for title '" . $fromtitle->getPrefixedDBkey() . "'\n" );
                        wfProfileOut( $fname );
                        return;
                }
                
                if ( $wgEnablePersistentLC ) {
                        if( $this->fillFromLinkscc( $id ) ){
                                wfProfileOut( $fname );
                                return;
                        }
                }

                $sql = "SELECT cur_id,cur_namespace,cur_title
                        FROM cur,links
                        WHERE cur_id=l_to AND l_from=$id";
                $res = wfQuery( $sql, DB_READ, $fname );
                while( $s = wfFetchObject( $res ) ) {
                        $this->addGoodLink( $s->cur_id,
                                Title::makeName( $s->cur_namespace, $s->cur_title )
                                );
                }
                
                $sql = "SELECT bl_to
                        FROM brokenlinks
                        WHERE bl_from='{$id}'";
                $res = wfQuery( $sql, DB_READ, "LinkCache::preFill" );
                while( $s = wfFetchObject( $res ) ) {
                        $this->addBadLink( $s->bl_to );
                }
                
                $this->mOldBadLinks = $this->mBadLinks;
                $this->mOldGoodLinks = $this->mGoodLinks;
                $this->mPreFilled = true;

                if ( $wgEnablePersistentLC ) {
                        $this->saveToLinkscc( $id );
                }
                wfProfileOut( $fname );
        }

        function getGoodAdditions() 
        {
                return array_diff( $this->mGoodLinks, $this->mOldGoodLinks );
        }

        function getBadAdditions() 
        {
                #wfDebug( "mOldBadLinks: " . implode( ', ', array_keys( $this->mOldBadLinks ) ) . "\n" );
                #wfDebug( "mBadLinks: " . implode( ', ', array_keys( $this->mBadLinks ) ) . "\n" );
                return array_values( array_diff( array_keys( $this->mBadLinks ), array_keys( $this->mOldBadLinks ) ) );
        }

        function getImageAdditions()
        {
                return array_diff_assoc( $this->mImageLinks, $this->mOldImageLinks );
        }

        function getGoodDeletions() 
        {
                return array_diff( $this->mOldGoodLinks, $this->mGoodLinks );
        }

        function getBadDeletions()
        {
                return array_values( array_diff( array_keys( $this->mOldBadLinks ), array_keys( $this->mBadLinks ) ));
        }

        function getImageDeletions()
        {
                return array_diff_assoc( $this->mOldImageLinks, $this->mImageLinks );
        }

        #     Parameters: $which is one of the LINKCACHE_xxx constants, $del and $add are 
        # the incremental update arrays which will be filled. Returns whether or not it's
        # worth doing the incremental version. For example, if [[List of mathematical topics]]
        # was blanked, it would take a long, long time to do incrementally.
        function incrementalSetup( $which, &$del, &$add )
        {
                if ( ! $this->mPreFilled ) {
                        return false;
                }

                switch ( $which ) {
                        case LINKCACHE_GOOD:
                                $old =& $this->mOldGoodLinks;
                                $cur =& $this->mGoodLinks;
                                $del = $this->getGoodDeletions();
                                $add = $this->getGoodAdditions();
                                break;
                        case LINKCACHE_BAD:
                                $old =& $this->mOldBadLinks;
                                $cur =& $this->mBadLinks;
                                $del = $this->getBadDeletions();
                                $add = $this->getBadAdditions();
                                break;
                        default: # LINKCACHE_IMAGE
                                return false;           
                }
                
                return true;
        }

        # Clears cache but leaves old preFill copies alone
        function clear() 
        {
                $this->mGoodLinks = array();
                $this->mBadLinks = array();
                $this->mImageLinks = array();
        }

        /* private */ function fillFromLinkscc( $id ){ 
                $id = IntVal( $id );
                $res = wfQuery("SELECT lcc_cacheobj FROM linkscc WHERE lcc_pageid = $id", 
                        DB_READ);
                $row = wfFetchObject( $res );
                if( $row == FALSE)
                        return false;   

                $cacheobj = false;
                if( function_exists( "gzuncompress" ) )
                        $cacheobj = @gzuncompress( $row->lcc_cacheobj );

                if($cacheobj == FALSE){
                        $cacheobj = $row->lcc_cacheobj;
                }
                $cc = @unserialize( $cacheobj );
                if( isset( $cc->mClassVer ) and ($cc->mClassVer == $this->mClassVer ) ){
                        $this->mOldGoodLinks = $this->mGoodLinks = $cc->mGoodLinks;
                        $this->mOldBadLinks = $this->mBadLinks = $cc->mBadLinks;
                        $this->mPreFilled = true;
                        return TRUE;
                } else {
                        return FALSE;
                }

        }

        /* private */ function saveToLinkscc( $pid ){
                global $wgCompressedPersistentLC, $wgIsMySQL;
                if( $wgCompressedPersistentLC and function_exists( "gzcompress" ) ) {
                        $ser = wfStrencode( gzcompress( serialize( $this ), 3 ));
                } else {
                        $ser = wfStrencode( serialize( $this ) );
                }
                if ($wgIsMySQL) {
                        wfQuery("REPLACE INTO linkscc(lcc_pageid,lcc_cacheobj) " .
                                "VALUES({$pid}, '{$ser}')", DB_WRITE);
                } else {
                        wfQuery("DELETE FROM linkscc WHERE lcc_pageid={$pid}",DB_WRITE);
                        wfQuery("INSERT INTO linkscc(lcc_pageid,lcc_cacheobj) " .
                                "VALUES({$pid}, '{$ser}')", DB_WRITE);
                }
        }

        # $pid is a page id
        /* static */ function linksccClearLinksTo( $pid ){
                global $wgEnablePersistentLC, $wgIsMySQL;
                if ( $wgEnablePersistentLC ) {
                        $pid = intval( $pid );
                        if ($wgIsMySQL) {
                                wfQuery("DELETE linkscc FROM linkscc,links ".
                                        "WHERE lcc_pageid=links.l_from AND l_to={$pid}", DB_WRITE);
                        } else {
                                wfQuery("DELETE FROM linkscc WHERE lcc_pageid IN ".
                                        "(SELECT l_from FROM links WHERE l_to={$pid})", DB_WRITE);
                        }
                        wfQuery("DELETE FROM linkscc WHERE lcc_pageid='{$pid}'", DB_WRITE);
                }
        }

        # $title is a prefixed db title, for example like Title->getPrefixedDBkey() returns.
        /* static */ function linksccClearBrokenLinksTo( $title ){
                global $wgEnablePersistentLC,$wgIsMySQL;
                if ( $wgEnablePersistentLC ) {
                        $title = wfStrencode( $title );
                        if ($wgIsMySQL) {
                                wfQuery("DELETE linkscc FROM linkscc,brokenlinks ".
                                        "WHERE lcc_pageid=bl_from AND bl_to='{$title}'", DB_WRITE);
                        } else {
                                wfQuery("DELETE FROM linkscc WHERE lcc_pageid IN ".
                                        "(SELECT bl_from FROM brokenlinks ".
                                        "WHERE bl_to='{$title}')",DB_WRITE);
                        }
                }
        }

        # $pid is a page id
        /* static */ function linksccClearPage( $pid ){
                global $wgEnablePersistentLC;
                if ( $wgEnablePersistentLC ) {
                        $pid = intval( $pid );
                        wfQuery("DELETE FROM linkscc WHERE lcc_pageid='{$pid}'", DB_WRITE);
                }
        }
}
?>

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