Implemented diff cache
authorTim Starling <tstarling@users.mediawiki.org>
Tue, 15 Nov 2005 11:12:21 +0000 (11:12 +0000)
committerTim Starling <tstarling@users.mediawiki.org>
Tue, 15 Nov 2005 11:12:21 +0000 (11:12 +0000)
includes/Article.php
includes/DifferenceEngine.php
includes/EditPage.php
includes/SpecialRecentchanges.php

index eb131c6..3dfd273 100644 (file)
@@ -693,7 +693,7 @@ class Article {
                        require_once( 'DifferenceEngine.php' );
                        $wgOut->setPageTitle( $this->mTitle->getPrefixedText() );
 
-                       $de = new DifferenceEngine( $oldid, $diff, $rcid );
+                       $de = new DifferenceEngine( $this->mTitle, $oldid, $diff, $rcid );
                        // DifferenceEngine directly fetched the revision:
                        $this->mRevIdFetched = $de->mNewid;
                        $de->showDiffPage();
index 7b2cadb..2650929 100644 (file)
@@ -21,23 +21,27 @@ class DifferenceEngine {
        /**#@+
         * @access private
         */
-       var $mOldid, $mNewid;
+       var $mOldid, $mNewid, $mTitle;
        var $mOldtitle, $mNewtitle, $mPagetitle;
        var $mOldtext, $mNewtext;
        var $mOldUser, $mNewUser;
        var $mOldComment, $mNewComment;
        var $mOldPage, $mNewPage;
        var $mRcidMarkPatrolled;
+       var $mOldRev, $mNewRev;
+       var $mRevisionsLoaded = false; // Have the revisions been loaded
+       var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
        /**#@-*/
 
        /**
         * Constructor
+        * @param Title $titleObj Title object that the diff is associated with
         * @param integer $old Old ID we want to show and diff with.
         * @param string $new Either 'prev' or 'next'. 
         * @param integer $rcid ??? (default 0)
         */
-       function DifferenceEngine( $old, $new, $rcid = 0 ) {
-               global $wgTitle;
+       function DifferenceEngine( $titleObj = null, $old = 0, $new = 0, $rcid = 0 ) {
+               $this->mTitle = $titleObj;
 
                if ( 'prev' == $new ) {
                        # Show diff between revision $old and the previous one.
@@ -45,14 +49,14 @@ class DifferenceEngine {
                        #
                        $this->mNewid = intval($old);
 
-                       $this->mOldid = $wgTitle->getPreviousRevisionID( $this->mNewid );
+                       $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
 
                } elseif ( 'next' == $new ) {
                        # Show diff between revision $old and the previous one.
                        # Get previous one from DB.
                        #
                        $this->mOldid = intval($old);
-                       $this->mNewid = $wgTitle->getNextRevisionID( $this->mOldid );
+                       $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
                        if ( false === $this->mNewid ) {
                                # if no result, NewId points to the newest old revision. The only newer
                                # revision is cur, which is "0".
@@ -67,7 +71,7 @@ class DifferenceEngine {
        }
 
        function showDiffPage() {
-               global $wgUser, $wgTitle, $wgOut, $wgContLang, $wgOnlySysopsCanPatrol,
+               global $wgUser, $wgOut, $wgContLang, $wgOnlySysopsCanPatrol,
                       $wgUseExternalEditor, $wgUseRCPatrol;
                $fname = 'DifferenceEngine::showDiffPage';
                wfProfileIn( $fname );
@@ -79,8 +83,8 @@ class DifferenceEngine {
                        global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
                        $wgOut->disable();
                        header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
-                       $url1=$wgTitle->getFullURL("action=raw&oldid=".$this->mOldid);                  
-                       $url2=$wgTitle->getFullURL("action=raw&oldid=".$this->mNewid);
+                       $url1=$this->mTitle->getFullURL("action=raw&oldid=".$this->mOldid);                     
+                       $url2=$this->mTitle->getFullURL("action=raw&oldid=".$this->mNewid);
                        $special=$wgLang->getNsText(NS_SPECIAL);
                        $control=<<<CONTROL
 [Process]
@@ -110,17 +114,21 @@ CONTROL;
                        return;
                }
 
-               $t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
+               $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
                  "{$this->mNewid})";
                $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 
                $wgOut->setArticleFlag( false );
-               if ( ! $this->loadText() ) {
+               if ( ! $this->loadRevisionData() ) {
                        $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
                        $wgOut->addWikitext( $mtext );
                        wfProfileOut( $fname );
                        return;
                }
+               if ( $this->mNewRev->isCurrent() ) {
+                       $wgOut->setArticleFlag( true );
+               }
+               
                $wgOut->suppressQuickbar();
 
                $oldTitle = $this->mOldPage->getPrefixedText();
@@ -155,10 +163,10 @@ CONTROL;
                        'target=' . urlencode($this->mOldUser) );
                $newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
                        'target=' . urlencode($this->mNewUser) );
-               if ( $this->newRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
-                       $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'rollbacklink' ),
+               if ( $this->mNewRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
+                       $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'rollbacklink' ),
                                'action=rollback&from=' . urlencode($this->mNewUser) .
-                               '&token=' . urlencode( $wgUser->editToken( array( $wgTitle->getPrefixedText(), $this->mNewUser ) ) ) ) .
+                               '&token=' . urlencode( $wgUser->editToken( array( $this->mTitle->getPrefixedText(), $this->mNewUser ) ) ) ) .
                                ']</strong>';
                } else {
                        $rollback = '';
@@ -166,18 +174,18 @@ CONTROL;
                if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->isLoggedIn() &&
                     ( $wgUser->isAllowed('rollback') || !$wgOnlySysopsCanPatrol ) )
                {
-                       $patrol = ' [' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'markaspatrolleddiff' ),
+                       $patrol = ' [' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'markaspatrolleddiff' ),
                                "action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) . ']';
                } else {
                        $patrol = '';
                }
 
-               $prevlink = $sk->makeKnownLinkObj( $wgTitle, wfMsgHtml( 'previousdiff' ),
+               $prevlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'previousdiff' ),
                        'diff=prev&oldid='.$this->mOldid, '', '', 'id="differences-prevlink"' );
-               if ( $this->newRev->isCurrent() ) {
+               if ( $this->mNewRev->isCurrent() ) {
                        $nextlink = '';
                } else {
-                       $nextlink = $sk->makeKnownLinkObj( $wgTitle, wfMsgHtml( 'nextdiff' ),
+                       $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ),
                                'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
                }
 
@@ -188,15 +196,17 @@ CONTROL;
                        "($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment .
                        '<br />' . $nextlink . $patrol;
 
-               DifferenceEngine::showDiff( $this->mOldtext, $this->mNewtext,
-                 $oldHeader, $newHeader );
+               $this->showDiff( $oldHeader, $newHeader );
                $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 
-               if( !$this->newRev->isCurrent() ) {
+               if( !$this->mNewRev->isCurrent() ) {
                        $oldEditSectionSetting = $wgOut->mParserOptions->setEditSection( false );
                }
+
+               $this->loadNewText();
                $wgOut->addWikiText( $this->mNewtext );
-               if( !$this->newRev->isCurrent() ) {
+
+               if( !$this->mNewRev->isCurrent() ) {
                        $wgOut->mParserOptions->setEditSection( $oldEditSectionSetting );
                }
 
@@ -208,18 +218,15 @@ CONTROL;
         * contrast to normal "old revision" display style.
         */
        function showFirstRevision() {
-               global $wgOut, $wgTitle, $wgUser, $wgLang;
+               global $wgOut, $wgUser, $wgLang;
 
                $fname = 'DifferenceEngine::showFirstRevision';
                wfProfileIn( $fname );
 
-
-               $this->mOldid = $this->mNewid; # hack to make loadText() work.
-
                # Get article text from the DB
                #
-               if ( ! $this->loadText() ) {
-                       $t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
+               if ( ! $this->loadNewText() ) {
+                       $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
                          "{$this->mNewid})";
                        $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
                        $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
@@ -227,10 +234,13 @@ CONTROL;
                        wfProfileOut( $fname );
                        return;
                }
+               if ( $this->mNewRev->isCurrent() ) {
+                       $wgOut->setArticleFlag( true );
+               }
 
                # Check if user is allowed to look at this page. If not, bail out.
                #
-               if ( !( $this->mOldPage->userCanRead() ) ) {
+               if ( !( $this->mTitle->userCanRead() ) ) {
                        $wgOut->loginToUse();
                        $wgOut->output();
                        wfProfileOut( $fname );
@@ -245,7 +255,7 @@ CONTROL;
                $userLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
                $contribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), wfMsg( 'contribslink' ),
                        'target=' . urlencode($this->mOldUser) );
-               $nextlink = $sk->makeKnownLinkObj( $wgTitle, wfMsgHtml( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
+               $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
                $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />$userLink " .
                        "($uTLink | $contribs)<br />" . $this->mOldComment .
                        '<br />' . $nextlink. "</div>\n";
@@ -264,23 +274,60 @@ CONTROL;
                wfProfileOut( $fname );
        }
 
-       function showDiff( $otext, $ntext, $otitle, $ntitle ) {
+       /**
+        * Get the diff text, send it to $wgOut
+        * Returns false if the diff could not be generated, otherwise returns true
+        */
+       function showDiff( $otitle, $ntitle ) {
                global $wgOut;
-               $wgOut->addHTML( DifferenceEngine::getDiff( $otext, $ntext, $otitle, $ntitle ) );
+               $diff = $this->getDiff( $otitle, $ntitle );
+               if ( $diff === false ) {
+                       $wgOut->addWikitext( wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" ) );
+                       return false;
+               } else {
+                       $wgOut->addHTML( $diff );
+                       return true;
+               }
        }
-       
-       function getDiff( $otext, $ntext, $otitle, $ntitle ) {
-               global $wgUseExternalDiffEngine, $wgContLang;
-               $out = "
-                       <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
-                       <tr>
-                               <td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
-                               <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
-                       </tr>
-               ";
-               $otext = $wgContLang->segmentForDiff($otext);
-               $ntext = $wgContLang->segmentForDiff($ntext);
-               $difftext='';
+
+       /**
+        * Get diff table, including header
+        * Note that the interface has changed, it's no longer static.
+        * Returns false on error
+        */
+       function getDiff( $otitle, $ntitle ) {
+               $body = $this->getDiffBody();
+               if ( $body === false ) {
+                       return false;
+               } else {
+                       return $this->addHeader( $body, $otitle, $ntitle );
+               }
+       }
+
+       /**
+        * Get the diff table body, without header
+        * Returns false on error
+        */
+       function getDiffBody() {
+               global $wgUseExternalDiffEngine, $wgContLang, $wgMemc, $wgDBname;
+               
+               // Cacheable?
+               $key = false;
+               if ( $this->mOldid && $this->mNewid ) {
+                       // Try cache
+                       $key = "$wgDBname:diff:oldid:{$this->mOldid}:newid:{$this->mNewid}";
+                       $difftext = $wgMemc->get( $key );
+                       if ( $difftext ) {
+                               return $difftext;
+                       }
+               }
+               
+               if ( !$this->loadText() ) {
+                       return false;
+               }
+               
+               $otext = $wgContLang->segmentForDiff($this->mOldtext);
+               $ntext = $wgContLang->segmentForDiff($this->mNewtext);
                if ( $wgUseExternalDiffEngine ) {
                        # For historical reasons, external diff engine expects
                        # input text to be HTML-escaped already
@@ -298,70 +345,154 @@ CONTROL;
                        $difftext = $formatter->format( $diffs );
                }
                $difftext = $wgContLang->unsegmentForDiff($difftext);
-               $out .= $difftext."</table>\n";
+
+               // Save to cache for 7 days
+               if ( $key !== false ) {
+                       $wgMemc->set( $key, $difftext, 7*86400 );
+               }
+               return $difftext;
+       }
+
+       /**
+        * Add the header to a diff body
+        */
+       function addHeader( $diff, $otitle, $ntitle ) {
+               $out = "
+                       <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
+                       <tr>
+                               <td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
+                               <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
+                       </tr>
+                       $diff
+                       </table>
+               ";
                return $out;
        }
 
+       /** 
+        * Use specified text instead of loading from the database
+        */
+       function setText( $oldText, $newText ) {
+               $this->mOldtext = $oldText;
+               $this->mNewtext = $newText;
+               $this->mTextLoaded = 2;
+       }
+
        /**
-        * Load the text of the articles to compare.  If newid is 0, then compare
+        * Load revision metadata for the specified articles. If newid is 0, then compare
         * the old article in oldid to the current article; if oldid is 0, then
         * compare the current article to the immediately previous one (ignoring the
-        * value of newid).
-        */     
-       function loadText() {
-               global $wgTitle, $wgOut, $wgLang;
-               $fname = 'DifferenceEngine::loadText';
+        * value of newid). 
+        *
+        * If oldid is false, leave the corresponding revision object set 
+        * to false. This is impossible via ordinary user input, and is provided for 
+        * API convenience. 
+        */
+       function loadRevisionData() {
+               global $wgLang;
+               if ( $this->mRevisionsLoaded ) {
+                       return true;
+               } else {
+                       // Whether it succeeds or fails, we don't want to try again
+                       $this->mRevisionsLoaded = true;
+               }
 
-               $dbr =& wfGetDB( DB_SLAVE );
+               // Load the new revision object
                if( $this->mNewid ) {
-                       $this->newRev = Revision::newFromId( $this->mNewid );
+                       $this->mNewRev = Revision::newFromId( $this->mNewid );
                } else {
-                       $this->newRev = Revision::newFromTitle( $wgTitle );
+                       $this->mNewRev = Revision::newFromTitle( $this->mTitle );
                }
-               if( is_null( $this->newRev ) ) {
+
+               if( is_null( $this->mNewRev ) ) {
                        return false;
                }
-               
-               if( $this->newRev->isCurrent() ) {
-                       $wgOut->setArticleFlag( true );
+
+               // Set assorted variables
+               if( $this->mNewRev->isCurrent() ) {
                        $this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
-                       $this->mNewPage = $wgTitle;
+                       $this->mNewPage = $this->mTitle;
                        $newLink = $this->mNewPage->escapeLocalUrl();
                        $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
                } else {
-                       $this->mNewPage = $this->newRev->getTitle();
+                       $this->mNewPage = $this->mNewRev->getTitle();
                        $newLink = $this->mNewPage->escapeLocalUrl ('oldid=' . $this->mNewid );
-                       $t = $wgLang->timeanddate( $this->newRev->getTimestamp(), true );
+                       $t = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
                        $this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t ) );
                        $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
                }
+                       
+               $this->mNewUser = $this->mNewRev->getUserText();
+               $this->mNewComment = $this->mNewRev->getComment();
                
+               // Load the old revision object
+               $this->mOldRev = false;
                if( $this->mOldid ) {
-                       $this->oldRev = Revision::newFromId( $this->mOldid );
-               } else {
-                       $this->oldRev = $this->newRev->getPrevious();
-                       $this->mOldid = $this->oldRev->getId();
-               }
-               if( is_null( $this->oldRev ) ) {
+                       $this->mOldRev = Revision::newFromId( $this->mOldid );
+               } elseif ( $this->mOldid === 0 ) {
+                       $this->mOldRev = $this->mNewRev->getPrevious();
+                       $this->mOldid = $this->mOldRev->getId();
+               }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
+
+               if( is_null( $this->mOldRev ) ) {
                        return false;
                }
-                       
-               $this->mOldPage = $this->oldRev->getTitle();
 
-               $t = $wgLang->timeanddate( $this->oldRev->getTimestamp(), true );
-               $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
-               $this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) ) . '</a>';
+               if ( $this->mOldRev ) {
+                       $this->mOldPage = $this->mOldRev->getTitle();
+
+                       $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
+                       $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
+                       $this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) ) . '</a>';
+
+                       
+                       $this->mOldUser = $this->mOldRev->getUserText();
+                       $this->mOldComment = $this->mOldRev->getComment();
+               }
                
-               $this->mNewUser = $this->newRev->getUserText();
-               $this->mNewComment = $this->newRev->getComment();
-               $this->mNewtext = $this->newRev->getText();
+               return true;
+       }
+
+       /**
+        * Load the text of the revisions, as well as revision data.
+        */
+       function loadText() {
+               if ( $this->mTextLoaded == 2 ) {
+                       return true;
+               } else {
+                       // Whether it succeeds or fails, we don't want to try again
+                       $this->mTextLoaded = 2;
+               }
                
-               $this->mOldUser = $this->oldRev->getUserText();
-               $this->mOldComment = $this->oldRev->getComment();
-               $this->mOldtext = $this->oldRev->getText();
+               if ( !$this->loadRevisionData() ) {
+                       return false;
+               }
+               if ( $this->mOldRev ) {
+                       $this->mOldtext = $this->mOldRev->getText();
+               }
+               if ( $this->mNewRev ) {
+                       $this->mNewtext = $this->mNewRev->getText();
+               }
+               return true;
+       }
 
+       /**
+        * Load the text of the new revision, not the old one
+        */
+       function loadNewText() {
+               if ( $this->mTextLoaded >= 1 ) {
+                       return true;
+               } else {
+                       $this->mTextLoaded = 1;
+               }
+               if ( !$this->loadRevisionData() ) {
+                       return false;
+               }
+               $this->mNewtext = $this->mNewRev->getText();
                return true;
        }
+               
+       
 }
 
 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
index 1b5f4a0..6b3c033 100644 (file)
@@ -897,8 +897,10 @@ END
                if ( $this->isConflict ) {
                        require_once( "DifferenceEngine.php" );
                        $wgOut->addWikiText( '==' . wfMsg( "yourdiff" ) . '==' );
-                       DifferenceEngine::showDiff( $this->textbox2, $this->textbox1,
-                         wfMsg( "yourtext" ), wfMsg( "storedversion" ) );
+
+                       $de = new DifferenceEngine( $this->mTitle );
+                       $de->setText( $this->textbox2, $this->textbox1 );
+                       $de->showDiff( wfMsg( "yourtext" ), wfMsg( "storedversion" ) );
 
                        $wgOut->addWikiText( '==' . wfMsg( "yourtext" ) . '==' );
                        $wgOut->addHTML( "<textarea tabindex=6 id='wpTextbox2' name=\"wpTextbox2\" rows='{$rows}' cols='{$cols}' wrap='virtual'>"
@@ -1384,8 +1386,12 @@ END
                        $this->section, $this->textbox1, $this->summary, $this->edittime );
                $oldtitle = wfMsg( 'currentrev' );
                $newtitle = wfMsg( 'yourtext' );
-               if ( $oldtext != wfMsg( $wgUser->isLoggedIn() ? 'noarticletext' : 'noarticletextanon' ) || $newtext != '' ) {
-                       $difftext = DifferenceEngine::getDiff( $oldtext, $newtext, $oldtitle, $newtitle );
+               if ( $oldtext !== false  || $newtext != '' ) {
+                       $de = new DifferenceEngine( $this->mTitle );
+                       $de->setText( $oldtext, $newtext );
+                       $difftext = $de->getDiff( $oldtitle, $newtitle );
+               } else {
+                       $difftext = '';
                }
 
                return '<div id="wikiDiff">' . $difftext . '</div>';
index 2f9e85f..bf7caf9 100644 (file)
@@ -150,26 +150,28 @@ function wfSpecialRecentchanges( $par, $specialPage ) {
        $batch = new LinkBatch;
        while( $row = $dbr->fetchObject( $res ) ){
                $rows[] = $row;
-               // User page link
-               $title = Title::makeTitleSafe( NS_USER, $row->rc_user_text );
-               $batch->addObj( $title );
-
-               // User talk
-               $title = Title::makeTitleSafe( NS_USER_TALK, $row->rc_user_text );
-               $batch->addObj( $title );
+               if ( !$feedFormat ) {
+                       // User page link
+                       $title = Title::makeTitleSafe( NS_USER, $row->rc_user_text );
+                       $batch->addObj( $title );
+
+                       // User talk
+                       $title = Title::makeTitleSafe( NS_USER_TALK, $row->rc_user_text );
+                       $batch->addObj( $title );
+               }
 
        }
        $dbr->freeResult( $res );
 
-       // Run existence checks
-       $batch->execute( $wgLinkCache );
-
        if( $feedFormat ) {
                rcOutputFeed( $rows, $feedFormat, $limit, $hideminor, $lastmod );
        } else {
 
                # Web output...
 
+               // Run existence checks
+               $batch->execute( $wgLinkCache );
+
                // Output header
                if ( !$specialPage->including() ) {
                        $wgOut->addWikiText( wfMsgForContent( "recentchangestext" ) );
@@ -486,46 +488,24 @@ function rcNamespaceForm ( $namespace, $invert, $nondefaults ) {
  * Format a diff for the newsfeed
  */
 function rcFormatDiff( $row ) {
+       global $wgFeedDiffCutoff, $wgContLang;
        $fname = 'rcFormatDiff';
        wfProfileIn( $fname );
 
        require_once( 'DifferenceEngine.php' );
-       $comment = '<p>' . htmlspecialchars( $row->rc_comment ) . "</p>\n";
+       $completeText = '<p>' . htmlspecialchars( $row->rc_comment ) . "</p>\n";
 
        if( $row->rc_namespace >= 0 ) {
-               global $wgContLang;
-
-               #$diff =& new DifferenceEngine( $row->rc_this_oldid, $row->rc_last_oldid, $row->rc_id );
-               #$diff->showDiffPage();
-
-               $titleObj = Title::makeTitle( $row->rc_namespace, $row->rc_title );
-               $dbr =& wfGetDB( DB_SLAVE );
-               $newrev = Revision::newFromTitle( $titleObj, $row->rc_this_oldid );
-               if( $newrev ) {
-                       $newtext = $newrev->getText();
-               } else {
-                       $diffText = "<p>Can't load revision $row->rc_this_oldid</p>";
-                       wfProfileOut( $fname );
-                       return $comment . $diffText;
-               }
-
                if( $row->rc_last_oldid ) {
                        wfProfileIn( "$fname-dodiff" );
-                       $oldrev =& Revision::newFromId( $row->rc_last_oldid );
-                       if( !$oldrev ) {
-                               $diffText = "<p>Can't load old revision $row->rc_last_oldid</p>";
-                               wfProfileOut( $fname );
-                               return $comment . $diffText;
-                       }
-                       $oldtext = $oldrev->getText();
 
-                       # Old entries may contain illegal characters
-                       # which will damage output
-                       $oldtext = UtfNormal::cleanUp( $oldtext );
+                       $titleObj = Title::makeTitle( $row->rc_namespace, $row->rc_title );
+                       $de = new DifferenceEngine( $titleObj, $row->rc_last_oldid, $row->rc_this_oldid );
+                       $diffText = $de->getDiff( wfMsg( 'revisionasof', $wgContLang->timeanddate( $row->rc_timestamp ) ),
+                               wfMsg( 'currentrev' ) );
 
-                       global $wgFeedDiffCutoff;
-                       if( strlen( $newtext ) > $wgFeedDiffCutoff ||
-                               strlen( $oldtext ) > $wgFeedDiffCutoff ) {
+                       if ( strlen( $diffText ) > $wgFeedDiffCutoff ) {
+                               // Omit large diffs
                                $diffLink = $titleObj->escapeFullUrl(
                                        'diff=' . $row->rc_this_oldid .
                                        '&oldid=' . $row->rc_last_oldid );
@@ -534,23 +514,23 @@ function rcFormatDiff( $row ) {
                                        '">' .
                                        htmlspecialchars( wfMsgForContent( 'difference' ) ) .
                                        '</a>';
+                       } elseif ( $diffText === false ) {
+                               // Error in diff engine, probably a missing revision
+                               $diffText = "<p>Can't load revision $row->rc_this_oldid</p>";
                        } else {
-                               $diffText = DifferenceEngine::getDiff( $oldtext, $newtext,
-                                 wfMsg( 'revisionasof', $wgContLang->timeanddate( $row->rc_timestamp ) ),
-                                 wfMsg( 'currentrev' ) );
+                               // Diff output fine, clean up any illegal UTF-8
+                               $diffText = UtfNormal::cleanUp( $diffText );
                        }
                        wfProfileOut( "$fname-dodiff" );
                } else {
                        $diffText = '<p><b>' . wfMsg( 'newpage' ) . '</b></p>' .
                                '<div>' . nl2br( htmlspecialchars( $newtext ) ) . '</div>';
                }
-
-               wfProfileOut( $fname );
-               return $comment . $diffText;
+               $completeText .= $diffText;
        }
 
        wfProfileOut( $fname );
-       return $comment;
+       return $completeText;
 }
 
 ?>