Merge remote-tracking branch 'origin/develop' into dbkr/email_notifs

1 files changed, 15 insertions, 3 deletions

diff --git a/synapse/state.py b/synapse/state.py
index 58211f5feb..d0f76dc4f5 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -214,7 +214,7 @@ class StateHandler(object):
 
         if self._state_cache is not None:
             cache = self._state_cache.get(group_names, None)
-            if cache and cache.state_group:
+            if cache:
                 cache.ts = self.clock.time_msec()
 
                 event_dict = yield self.store.get_events(cache.state.values())
@@ -230,22 +230,34 @@ class StateHandler(object):
                     (cache.state_group, state, prev_states)
                 )
 
+        logger.info("Resolving state for %s with %d groups", room_id, len(state_groups))
+
         new_state, prev_states = self._resolve_events(
             state_groups.values(), event_type, state_key
         )
 
+        state_group = None
+        new_state_event_ids = frozenset(e.event_id for e in new_state.values())
+        for sg, events in state_groups.items():
+            if new_state_event_ids == frozenset(e.event_id for e in events):
+                state_group = sg
+                break
+
         if self._state_cache is not None:
             cache = _StateCacheEntry(
                 state={key: event.event_id for key, event in new_state.items()},
-                state_group=None,
+                state_group=state_group,
                 ts=self.clock.time_msec()
             )
 
             self._state_cache[group_names] = cache
 
-        defer.returnValue((None, new_state, prev_states))
+        defer.returnValue((state_group, new_state, prev_states))
 
     def resolve_events(self, state_sets, event):
+        logger.info(
+            "Resolving state for %s with %d groups", event.room_id, len(state_sets)
+        )
         if event.is_state():
             return self._resolve_events(
                 state_sets, event.type, event.state_key