* Added a TODO note to isASCII()

[mediawiki.git] / includes / LinkCache.php

<?php
/**
 * Cache for article titles (prefixed DB keys) and ids linked from one source
 * @package MediaWiki
 * @subpackage Cache
 */

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

/**
 * @package MediaWiki
 * @subpackage Cache
 */
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 */ var $mForUpdate;

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

        /**
         * General accessor to get/set whether SELECT FOR UPDATE should be used
         */
        function forUpdate( $update = NULL ) { 
                return wfSetVar( $this->mForUpdate, $update );
        }
        
        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 ) ) {
                        if ( $this->mForUpdate ) {
                                $db =& wfGetDB( DB_MASTER );
                                $options = array( 'FOR UPDATE' );
                        } else {
                                $db =& wfGetDB( DB_SLAVE );
                                $options = array();
                        }

                        $id = $db->selectField( 'page', 'page_id', array( 'page_namespace' => $ns, 'page_title' => $t ), $fname, $options );
                        if ( !$id ) {
                                $id = 0;
                        }
                        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;
                        }
                }
                if ( $this->mForUpdate ) {
                        $db =& wfGetDB( DB_MASTER );
                        $options = 'FOR UPDATE';
                } else {
                        $db =& wfGetDB( DB_SLAVE );
                        $options = '';
                }

                $page = $db->tableName( 'page' );
                $links = $db->tableName( 'links' );

                $sql = "SELECT page_id,page_namespace,page_title
                        FROM $page,$links
                        WHERE page_id=l_to AND l_from=$id $options";
                $res = $db->query( $sql, $fname );
                while( $s = $db->fetchObject( $res ) ) {
                        $this->addGoodLink( $s->page_id,
                                Title::makeName( $s->page_namespace, $s->page_title )
                                );
                }
                
                $res = $db->select( 'brokenlinks', array( 'bl_to' ), array( 'bl_from' => $id ), $fname, array( $options ) );
                while( $s = $db->fetchObject( $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:
         * @param $which is one of the LINKCACHE_xxx constants
         * @param $del,$add are the incremental update arrays which will be filled.
         *
         * @return 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();
        }

        /**
         * @access private
         */
        function fillFromLinkscc( $id ){ 
                $fname = 'LinkCache::fillFromLinkscc';

                $id = IntVal( $id );
                if ( $this->mForUpdate ) {
                        $db =& wfGetDB( DB_MASTER );
                        $options = 'FOR UPDATE';
                } else {
                        $db =& wfGetDB( DB_SLAVE );
                        $options = '';
                }
                $raw = $db->selectField( 'linkscc', 'lcc_cacheobj', array( 'lcc_pageid' => $id ), $fname, $options );
                if ( $raw === false ) {
                        return false;
                }
                
                $cacheobj = false;
                if( function_exists( 'gzuncompress' ) )
                        $cacheobj = @gzuncompress( $raw );

                if($cacheobj == FALSE){
                        $cacheobj = $raw;
                }
                $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;
                }

        }

        /**
         * @access private
         */
        function saveToLinkscc( $pid ){
                global $wgCompressedPersistentLC;
                if( $wgCompressedPersistentLC and function_exists( 'gzcompress' ) ) {
                        $ser = gzcompress( serialize( $this ), 3 );
                } else {
                        $ser = serialize( $this );
                }
                $db =& wfGetDB( DB_MASTER );
                $db->replace( 'linkscc', array( 'lcc_pageid' ), array( 'lcc_pageid' => $pid, 'lcc_cacheobj' => $ser ) );
        }

        /**
         * Delete linkscc rows which link to here
         * @param $pid is a page id
         * @static
         */
        function linksccClearLinksTo( $pid ){
                global $wgEnablePersistentLC;
                if ( $wgEnablePersistentLC ) {
                        $fname = 'LinkCache::linksccClearLinksTo';
                        $pid = intval( $pid );
                        $dbw =& wfGetDB( DB_MASTER );
                        # Delete linkscc rows which link to here
                        $dbw->deleteJoin( 'linkscc', 'links', 'lcc_pageid', 'l_from', array( 'l_to' => $pid ), $fname );
                        # Delete linkscc row representing this page
                        $dbw->delete( 'linkscc', array( 'lcc_pageid' => $pid ), $fname);
                }

        }

        /**
         * Delete linkscc rows with broken links to here
         * @param $title is a prefixed db title for example like Title->getPrefixedDBkey() returns.
         * @static
         */
        function linksccClearBrokenLinksTo( $title ){
                global $wgEnablePersistentLC;
                $fname = 'LinkCache::linksccClearBrokenLinksTo';

                if ( $wgEnablePersistentLC ) {
                        $dbw =& wfGetDB( DB_MASTER );
                        $dbw->deleteJoin( 'linkscc', 'brokenlinks', 'lcc_pageid', 'bl_from', array( 'bl_to' => $title ), $fname );
                }
        }

        /**
         * @param $pid is a page id
         * @static
         */
        function linksccClearPage( $pid ){
                global $wgEnablePersistentLC;
                if ( $wgEnablePersistentLC ) {
                        $pid = intval( $pid );
                        $dbw =& wfGetDB( DB_MASTER );
                        $dbw->delete( 'linkscc', array( 'lcc_pageid' => $pid ) );
                }
        }
}

/**
 * Class representing a list of titles
 * The execute() method checks them all for existence and adds them to a LinkCache object
 +
 * @package MediaWikki
 * @subpackage Cache
 */
class LinkBatch {
        /** 
         * 2-d array, first index namespace, second index dbkey, value arbitrary
         */
        var $data = array();

        function addObj( $title ) {
                $this->add( $title->getNamespace(), $title->getDBkey() );
        }

        function add( $ns, $dbkey ) {
                if ( $ns < 0 ) {
                        return;
                }
                if ( !array_key_exists( $ns, $this->data ) ) {
                        $this->data[$ns] = array();
                }

                $this->data[$ns][$dbkey] = 1;
        }

        function execute( &$cache ) {
                $fname = 'LinkBatch::execute';
                $namespaces = array();

                if ( !count( $this->data ) ) {
                        return;
                }

                wfProfileIn( $fname );

                // Construct query
                // This is very similar to Parser::replaceLinkHolders
                $dbr = wfGetDB( DB_SLAVE );
                $page = $dbr->tableName( 'page' );
                $sql = "SELECT page_id, page_namespace, page_title FROM $page WHERE ";
                $first = true;
                
                foreach ( $this->data as $ns => $dbkeys ) {
                        if ( !count( $dbkeys ) ) {
                                continue;
                        }

                        if ( $first ) {
                                $first = false;
                        } else {
                                $sql .= ' OR ';
                        }
                        $sql .= "(page_namespace=$ns AND page_title IN (";

                        $firstTitle = true;
                        foreach( $dbkeys as $dbkey => $nothing ) {
                                if ( $firstTitle ) {
                                        $firstTitle = false;
                                } else {
                                        $sql .= ',';
                                }
                                $sql .= $dbr->addQuotes( $dbkey );
                        }

                        $sql .= '))';
                }
                
                // Do query
                $res = $dbr->query( $sql, $fname );

                // Process results
                // For each returned entry, add it to the list of good links, and remove it from $remaining

                $remaining = $this->data;
                while ( $row = $dbr->fetchObject( $res ) ) {
                        $title = Title::makeTitle( $row->page_namespace, $row->page_title );
                        $cache->addGoodLink( $row->page_id, $title->getPrefixedDBkey() );
                        unset( $remaining[$row->page_namespace][$row->page_title] );
                }
                $dbr->freeResult( $res );

                // The remaining links in $data are bad links, register them as such
                foreach ( $remaining as $ns => $dbkeys ) {
                        foreach ( $dbkeys as $dbkey => $nothing ) {
                                $title = Title::makeTitle( $ns, $dbkey );
                                $cache->addBadLink( $title->getPrefixedText() );
                        }
                }

                wfProfileOut( $fname );
        }
}

?>