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, 5 insertions, 3 deletions

diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index 7469cc55a2..472688f045 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -537,14 +537,16 @@ class PaginationHandler:
                 state_dict = await self.store.get_events(list(state_ids.values()))
                 state = state_dict.values()
 
+        aggregations = await self.store.get_bundled_aggregations(events)
+
         time_now = self.clock.time_msec()
 
         chunk = {
             "chunk": (
-                await self._event_serializer.serialize_events(
+                self._event_serializer.serialize_events(
                     events,
                     time_now,
-                    bundle_aggregations=True,
+                    bundle_aggregations=aggregations,
                     as_client_event=as_client_event,
                 )
             ),
@@ -553,7 +555,7 @@ class PaginationHandler:
         }
 
         if state:
-            chunk["state"] = await self._event_serializer.serialize_events(
+            chunk["state"] = self._event_serializer.serialize_events(
                 state, time_now, as_client_event=as_client_event
             )