wiki.techinc.nl/includes/LinkCache.php

<?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 ) ) {
			$dbr =& wfGetDB( DB_READ );
			$id = $dbr->getField( 'cur', 'cur_id', array( 'cur_namespace' => $ns, 'cur_title' => $t ), $fname );
			if ( !$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;
			}
		}

		$dbr =& wfGetDB( DB_READ );
		$cur = $dbr->tableName( 'cur' );
		$links = $dbr->tableName( 'links' );

		$sql = "SELECT cur_id,cur_namespace,cur_title
			FROM $cur,$links
			WHERE cur_id=l_to AND l_from=$id";
		$res = $dbr->query( $sql, $fname );
		while( $s = $dbr->fetchObject( $res ) ) {
			$this->addGoodLink( $s->cur_id,
				Title::makeName( $s->cur_namespace, $s->cur_title )
				);
		}
		
		$res = $dbr->select( 'brokenlinks', array( 'bl_to' ), array( 'bl_from' => $id ), $fname );
		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 );
		$dbr =& wfGetDB( DB_READ );
		$raw = $dbr->getField( 'linkscc', 'lcc_cacheobj', array( 'lcc_pageid' => $id ) );
		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;
		}

	}

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

	# Delete linkscc rows which link to here
	# $pid is a page id
	/* static */ function linksccClearLinksTo( $pid ){
		global $wgEnablePersistentLC;
		if ( $wgEnablePersistentLC ) {
			$fname = "LinkCache::linksccClearLinksTo";
			$pid = intval( $pid );
			$dbw =& wfGetDB( DB_WRITE );
			# 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
	# $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_WRITE );
			$dbw->deleteJoin( 'linkscc', 'brokenlinks', 'lcc_pageid', 'bl_from', array( 'bl_to' => $title ), $fname );
		}
	}

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