Consistently return a Deferred in the descriptor cache

synapse/push/bulk_push_rule_evaluator.py

@@ -76,7 +76,7 @@ def _get_rules_for_event(self, event, context):
             dict of user_id -> push_rules
         """
         room_id = event.room_id
-        rules_for_room = self._get_rules_for_room(room_id)
+        rules_for_room = yield self._get_rules_for_room(room_id)
 
         rules_by_user = yield rules_for_room.get_rules(event, context)
 

synapse/util/caches/descriptors.py

@@ -216,8 +216,9 @@ def invalidate_all(self):
 class _CacheDescriptorBase(object):
     def __init__(self, orig, num_args, inlineCallbacks, cache_context=False):
         self.orig = orig
+        self.inlineCallbacks = inlineCallbacks
 
-        if inlineCallbacks:
+        if self.inlineCallbacks:
             self.function_to_call = defer.inlineCallbacks(orig)
         else:
             self.function_to_call = orig
@@ -380,6 +381,8 @@ def wrapped(*args, **kwargs):
 
                 if isinstance(cached_result_d, ObservableDeferred):
                     observer = cached_result_d.observe()
+                elif self.inlineCallbacks:
+                    observer = defer.succeed(cached_result_d)
                 else:
                     observer = cached_result_d