RSS update time and 304 Not Modified

  - Gives the wiki administrator control over how often the RSS feed is regenerated.
  - The RSS feed now handles conditional requests and returns HTTP '304 Not Modified'
    responses when possible.

darcs-hash:20060324133315-05dcb-3b814e28523f2a0717222a4940d6fbbb28576cf5.gz

conf/dokuwiki.php

@@ -94,6 +94,7 @@ $conf['rss_linkto'] = 'diff';            //what page RSS entries link to:
                                          //  'page'    - the revised page itself
                                          //  'rev'     - page showing all revisions
                                          //  'current' - most recent revision of page
+$conf['rss_update'] = 5*60;              //Update the RSS feed every n minutes (defaults to 5 minutes)
 
 //Set target to use when creating links - leave empty for same window
 $conf['target']['wiki']      = '';

feed.php

@@ -12,6 +12,7 @@
   require_once(DOKU_INC.'inc/parserutils.php');
   require_once(DOKU_INC.'inc/feedcreator.class.php');
   require_once(DOKU_INC.'inc/auth.php');
+  require_once(DOKU_INC.'inc/pageutils.php');
 
   //close session
   session_write_close();
@@ -46,12 +47,17 @@
   $cache = getCacheName($num.$type.$mode.$ns.$ltype.$_SERVER['REMOTE_USER'],'.feed');
 
   // check cacheage and deliver if nothing has changed since last
-  // time (with 5 minutes settletime)
+  // time or the update interval has not passed, also handles conditional requests
+  header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
+  header('Pragma: public');
+  header('Content-Type: application/xml; charset=utf-8');
   $cmod = @filemtime($cache); // 0 if not exists
-  if($cmod && ($cmod+(5*60) >= @filemtime($conf['changelog']))){
-    header('Content-Type: application/xml; charset=utf-8');
+  if($cmod && (($cmod+$conf['rss_update']>time()) || ($cmod>@filemtime($conf['changelog'])))){
+    http_conditionalRequest($cmod);
     print io_readFile($cache);
     exit;
+  } else {
+    http_conditionalRequest(time());
   }
 
   // create new feed
@@ -79,7 +85,6 @@
   io_saveFile($cache,$feed);
 
   // finally deliver
-  header('Content-Type: application/xml; charset=utf-8');
   print $feed;
 
 // ---------------------------------------------------------------- //