Bundle aggregations outside of the serialization method. (#11612)

This makes the serialization of events synchronous (and it no
longer access the database), but we must manually calculate and
provide the bundled aggregations.

Overall this should cause no change in behavior, but is prep work
for other improvements.

1 files changed, 18 insertions, 10 deletions

diff --git a/synapse/rest/client/room.py b/synapse/rest/client/room.py
index 40330749e5..da6014900a 100644
--- a/synapse/rest/client/room.py
+++ b/synapse/rest/client/room.py
@@ -642,6 +642,7 @@ class RoomEventServlet(RestServlet):
     def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.clock = hs.get_clock()
+        self._store = hs.get_datastore()
         self.event_handler = hs.get_event_handler()
         self._event_serializer = hs.get_event_client_serializer()
         self.auth = hs.get_auth()
@@ -660,10 +661,13 @@ class RoomEventServlet(RestServlet):
             # https://matrix.org/docs/spec/client_server/r0.5.0#get-matrix-client-r0-rooms-roomid-event-eventid
             raise SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)
 
-        time_now = self.clock.time_msec()
         if event:
-            event_dict = await self._event_serializer.serialize_event(
-                event, time_now, bundle_aggregations=True
+            # Ensure there are bundled aggregations available.
+            aggregations = await self._store.get_bundled_aggregations([event])
+
+            time_now = self.clock.time_msec()
+            event_dict = self._event_serializer.serialize_event(
+                event, time_now, bundle_aggregations=aggregations
             )
             return 200, event_dict
 
@@ -708,16 +712,20 @@ class RoomEventContextServlet(RestServlet):
             raise SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)
 
         time_now = self.clock.time_msec()
-        results["events_before"] = await self._event_serializer.serialize_events(
-            results["events_before"], time_now, bundle_aggregations=True
+        results["events_before"] = self._event_serializer.serialize_events(
+            results["events_before"],
+            time_now,
+            bundle_aggregations=results["aggregations"],
         )
-        results["event"] = await self._event_serializer.serialize_event(
-            results["event"], time_now, bundle_aggregations=True
+        results["event"] = self._event_serializer.serialize_event(
+            results["event"], time_now, bundle_aggregations=results["aggregations"]
         )
-        results["events_after"] = await self._event_serializer.serialize_events(
-            results["events_after"], time_now, bundle_aggregations=True
+        results["events_after"] = self._event_serializer.serialize_events(
+            results["events_after"],
+            time_now,
+            bundle_aggregations=results["aggregations"],
         )
-        results["state"] = await self._event_serializer.serialize_events(
+        results["state"] = self._event_serializer.serialize_events(
             results["state"], time_now
         )