Do not bundle aggregations for APIs which shouldn't include them. (#11592)

And make bundling aggregations opt-in, instead of opt-out to avoid
having APIs to include extraneous data (and being much heavier than
necessary).

9 files changed, 31 insertions, 27 deletions

diff --git a/changelog.d/11592.bugfix b/changelog.d/11592.bugfix
new file mode 100644
index 0000000000..4116e5dd7c
--- /dev/null
+++ b/changelog.d/11592.bugfix
@@ -0,0 +1 @@
+Fix a long-standing bug where responses included bundled aggregations when they should not, per [MSC2675](https://github.com/matrix-org/matrix-doc/pull/2675).
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 3da432c1df..2038e72924 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -395,7 +395,7 @@ class EventClientSerializer:
         event: Union[JsonDict, EventBase],
         time_now: int,
         *,
-        bundle_aggregations: bool = True,
+        bundle_aggregations: bool = False,
         **kwargs: Any,
     ) -> JsonDict:
         """Serializes a single event.
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index afed80ba14..1b996c420d 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -123,8 +123,6 @@ class EventStreamHandler:
                 events,
                 time_now,
                 as_client_event=as_client_event,
-                # Don't bundle aggregations as this is a deprecated API.
-                bundle_aggregations=False,
             )
 
             chunk = {
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index 9ab723ff97..601bab67f9 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -173,8 +173,6 @@ class InitialSyncHandler:
                 d["invite"] = await self._event_serializer.serialize_event(
                     invite_event,
                     time_now,
-                    # Don't bundle aggregations as this is a deprecated API.
-                    bundle_aggregations=False,
                     as_client_event=as_client_event,
                 )
 
@@ -227,8 +225,6 @@ class InitialSyncHandler:
                         await self._event_serializer.serialize_events(
                             messages,
                             time_now=time_now,
-                            # Don't bundle aggregations as this is a deprecated API.
-                            bundle_aggregations=False,
                             as_client_event=as_client_event,
                         )
                     ),
@@ -239,8 +235,6 @@ class InitialSyncHandler:
                 d["state"] = await self._event_serializer.serialize_events(
                     current_state.values(),
                     time_now=time_now,
-                    # Don't bundle aggregations as this is a deprecated API.
-                    bundle_aggregations=False,
                     as_client_event=as_client_event,
                 )
 
@@ -382,9 +376,7 @@ class InitialSyncHandler:
             "messages": {
                 "chunk": (
                     # Don't bundle aggregations as this is a deprecated API.
-                    await self._event_serializer.serialize_events(
-                        messages, time_now, bundle_aggregations=False
-                    )
+                    await self._event_serializer.serialize_events(messages, time_now)
                 ),
                 "start": await start_token.to_string(self.store),
                 "end": await end_token.to_string(self.store),
@@ -392,7 +384,7 @@ class InitialSyncHandler:
             "state": (
                 # Don't bundle aggregations as this is a deprecated API.
                 await self._event_serializer.serialize_events(
-                    room_state.values(), time_now, bundle_aggregations=False
+                    room_state.values(), time_now
                 )
             ),
             "presence": [],
@@ -413,7 +405,7 @@ class InitialSyncHandler:
         time_now = self.clock.time_msec()
         # Don't bundle aggregations as this is a deprecated API.
         state = await self._event_serializer.serialize_events(
-            current_state.values(), time_now, bundle_aggregations=False
+            current_state.values(), time_now
         )
 
         now_token = self.hs.get_event_sources().get_current_token()
@@ -488,9 +480,7 @@ class InitialSyncHandler:
             "messages": {
                 "chunk": (
                     # Don't bundle aggregations as this is a deprecated API.
-                    await self._event_serializer.serialize_events(
-                        messages, time_now, bundle_aggregations=False
-                    )
+                    await self._event_serializer.serialize_events(messages, time_now)
                 ),
                 "start": await start_token.to_string(self.store),
                 "end": await end_token.to_string(self.store),
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 5e3d3886eb..1a7190085a 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -246,7 +246,9 @@ class MessageHandler:
                 room_state = room_state_events[membership_event_id]
 
         now = self.clock.time_msec()
-        events = await self._event_serializer.serialize_events(room_state.values(), now)
+        events = await self._event_serializer.serialize_events(
+            room_state.values(), now, bundle_aggregations=True
+        )
         return events
 
     async def get_joined_members(self, requester: Requester, room_id: str) -> dict:
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index 4f42438053..7469cc55a2 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -542,7 +542,10 @@ class PaginationHandler:
         chunk = {
             "chunk": (
                 await self._event_serializer.serialize_events(
-                    events, time_now, as_client_event=as_client_event
+                    events,
+                    time_now,
+                    bundle_aggregations=True,
+                    as_client_event=as_client_event,
                 )
             ),
             "start": await from_token.to_string(self.store),
diff --git a/synapse/rest/admin/rooms.py b/synapse/rest/admin/rooms.py
index 17c6df1cc8..6030373ebc 100644
--- a/synapse/rest/admin/rooms.py
+++ b/synapse/rest/admin/rooms.py
@@ -745,13 +745,19 @@ class RoomEventContextServlet(RestServlet):
 
         time_now = self.clock.time_msec()
         results["events_before"] = await self._event_serializer.serialize_events(
-            results["events_before"], time_now
+            results["events_before"],
+            time_now,
+            bundle_aggregations=True,
         )
         results["event"] = await self._event_serializer.serialize_event(
-            results["event"], time_now
+            results["event"],
+            time_now,
+            bundle_aggregations=True,
         )
         results["events_after"] = await self._event_serializer.serialize_events(
-            results["events_after"], time_now
+            results["events_after"],
+            time_now,
+            bundle_aggregations=True,
         )
         results["state"] = await self._event_serializer.serialize_events(
             results["state"], time_now
diff --git a/synapse/rest/client/relations.py b/synapse/rest/client/relations.py
index ffa37ef06c..5815650ee6 100644
--- a/synapse/rest/client/relations.py
+++ b/synapse/rest/client/relations.py
@@ -232,7 +232,9 @@ class RelationPaginationServlet(RestServlet):
         )
         # The relations returned for the requested event do include their
         # bundled aggregations.
-        serialized_events = await self._event_serializer.serialize_events(events, now)
+        serialized_events = await self._event_serializer.serialize_events(
+            events, now, bundle_aggregations=True
+        )
 
         return_value = pagination_chunk.to_dict()
         return_value["chunk"] = serialized_events
diff --git a/synapse/rest/client/room.py b/synapse/rest/client/room.py
index 60719331b6..40330749e5 100644
--- a/synapse/rest/client/room.py
+++ b/synapse/rest/client/room.py
@@ -662,7 +662,9 @@ class RoomEventServlet(RestServlet):
 
         time_now = self.clock.time_msec()
         if event:
-            event_dict = await self._event_serializer.serialize_event(event, time_now)
+            event_dict = await self._event_serializer.serialize_event(
+                event, time_now, bundle_aggregations=True
+            )
             return 200, event_dict
 
         raise SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)
@@ -707,13 +709,13 @@ class RoomEventContextServlet(RestServlet):
 
         time_now = self.clock.time_msec()
         results["events_before"] = await self._event_serializer.serialize_events(
-            results["events_before"], time_now
+            results["events_before"], time_now, bundle_aggregations=True
         )
         results["event"] = await self._event_serializer.serialize_event(
-            results["event"], time_now
+            results["event"], time_now, bundle_aggregations=True
         )
         results["events_after"] = await self._event_serializer.serialize_events(
-            results["events_after"], time_now
+            results["events_after"], time_now, bundle_aggregations=True
         )
         results["state"] = await self._event_serializer.serialize_events(
             results["state"], time_now