1 files changed, 41 insertions, 1 deletions
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index a134e9b3e8..d14a7b2538 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -428,14 +428,54 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
"""
# for now we do this by looking at the create event. We may want to cache this
# more intelligently in future.
+
+ # Retrieve the room's create event
+ create_event = yield self.get_create_event_for_room(room_id)
+ defer.returnValue(create_event.content.get("room_version", "1"))
+
+ @defer.inlineCallbacks
+ def get_room_predecessor(self, room_id):
+ """Get the predecessor room of an upgraded room if one exists.
+ Otherwise return None.
+
+ Args:
+ room_id (str)
+
+ Returns:
+ Deferred[unicode|None]: predecessor room id
+
+ Raises:
+ NotFoundError if the room is unknown
+ """
+ # Retrieve the room's create event
+ create_event = yield self.get_create_event_for_room(room_id)
+
+ # Return predecessor if present
+ defer.returnValue(create_event.content.get("predecessor", None))
+
+ @defer.inlineCallbacks
+ def get_create_event_for_room(self, room_id):
+ """Get the create state event for a room.
+
+ Args:
+ room_id (str)
+
+ Returns:
+ Deferred[EventBase]: The room creation event.
+
+ Raises:
+ NotFoundError if the room is unknown
+ """
state_ids = yield self.get_current_state_ids(room_id)
create_id = state_ids.get((EventTypes.Create, ""))
+ # If we can't find the create event, assume we've hit a dead end
if not create_id:
raise NotFoundError("Unknown room %s" % (room_id))
+ # Retrieve the room's create event and return
create_event = yield self.get_event(create_id)
- defer.returnValue(create_event.content.get("room_version", "1"))
+ defer.returnValue(create_event)
@cached(max_entries=100000, iterable=True)
def get_current_state_ids(self, room_id):
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