diff --git a/src/cmsplugin_blurp/renderers/data_source.py b/src/cmsplugin_blurp/renderers/data_source.py
index 8cd08b7..54ee8da 100644
--- a/src/cmsplugin_blurp/renderers/data_source.py
+++ b/src/cmsplugin_blurp/renderers/data_source.py
@@ -247,8 +247,8 @@ class Data(object):
                 return msg
             return None
         if self.refresh and data is not None:
+            log.debug('set cache for url %r with key %r', self.url, self.key)
             cache.set(self.key, (data, self.now+self.refresh), 86400*12)
-        log.debug('finished')
         if self.key in self.UPDATE_THREADS:
             c = self.CONDITIONS.setdefault(self.key, threading.Condition())
             with c:
@@ -264,16 +264,22 @@ class Data(object):
             return self.__content
         self.__content, until = cache.get(self.key, (self.__CACHE_SENTINEL, None))
         use_cache = self.__content is not self.__CACHE_SENTINEL
+        if not use_cache:
+            log.debug('found content in cache for url %r', self.url)
         # do not use cache if refresh timeout is 0
         use_cache = use_cache and self.refresh > 0
+        if self.refresh == 0:
+            log.debug('self refresh is 0, ignoring cache')
         # do not use cache if updatecache is present in the query string
         use_cache = use_cache and (not self.request or 'updatecache' not in self.request.GET)
+        if self.request and 'updatecache' not in self.request.GET:
+            log.debug('updatecache in query string, ignoring cache')
 
         if use_cache:
             if until < self.now:
                 # reload cache content asynchronously in a thread
                 # and return the current content
-                log.debug('stale content reloading')
+                log.debug('asynchronous update for url %r', self.url)
                 c = self.CONDITIONS.setdefault(self.key, threading.Condition())
                 t = threading.Thread(target=self.update_content)
                 t2 = self.UPDATE_THREADS.setdefault(self.key, t)
@@ -288,6 +294,7 @@ class Data(object):
                                 c.wait()
                     t2.join()
         else:
+            log.debug('synchronous update for url %r', self.url)
             self.__content = self.update_content()
         return self.__content
     content = property(get_content)