From 5274c8779b714e84a61e4807fb68f3961efaf1f6 Mon Sep 17 00:00:00 2001
From: Sean Quah <seanq@matrix.org>
Date: Fri, 5 Aug 2022 22:31:50 +0100
Subject: [PATCH] Do not wait for full state in `compute_state_delta`

Signed-off-by: Sean Quah <seanq@matrix.org>
---
 synapse/handlers/sync.py | 38 ++++++++++++++++++++++++++++++--------
 1 file changed, 30 insertions(+), 8 deletions(-)

diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index a10a61363b..d2672378a1 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -964,19 +964,26 @@ class SyncHandler:
                 if batch:
                     state_at_timeline_end = (
                         await self._state_storage_controller.get_state_ids_for_event(
-                            batch.events[-1].event_id, state_filter=state_filter
+                            batch.events[-1].event_id,
+                            state_filter=state_filter,
+                            await_full_state=not lazy_load_members,
                         )
                     )
 
                     state_at_timeline_start = (
                         await self._state_storage_controller.get_state_ids_for_event(
-                            batch.events[0].event_id, state_filter=state_filter
+                            batch.events[0].event_id,
+                            state_filter=state_filter,
+                            await_full_state=not lazy_load_members,
                         )
                     )
 
                 else:
                     state_at_timeline_end = await self.get_state_at(
-                        room_id, stream_position=now_token, state_filter=state_filter
+                        room_id,
+                        stream_position=now_token,
+                        state_filter=state_filter,
+                        await_full_state=not lazy_load_members,
                     )
 
                     state_at_timeline_start = state_at_timeline_end
@@ -992,14 +999,19 @@ class SyncHandler:
                 if batch:
                     state_at_timeline_start = (
                         await self._state_storage_controller.get_state_ids_for_event(
-                            batch.events[0].event_id, state_filter=state_filter
+                            batch.events[0].event_id,
+                            state_filter=state_filter,
+                            await_full_state=not lazy_load_members,
                         )
                     )
                 else:
                     # We can get here if the user has ignored the senders of all
                     # the recent events.
                     state_at_timeline_start = await self.get_state_at(
-                        room_id, stream_position=now_token, state_filter=state_filter
+                        room_id,
+                        stream_position=now_token,
+                        state_filter=state_filter,
+                        await_full_state=not lazy_load_members,
                     )
 
                 # for now, we disable LL for gappy syncs - see
@@ -1021,20 +1033,28 @@ class SyncHandler:
                 # is indeed the case.
                 assert since_token is not None
                 state_at_previous_sync = await self.get_state_at(
-                    room_id, stream_position=since_token, state_filter=state_filter
+                    room_id,
+                    stream_position=since_token,
+                    state_filter=state_filter,
+                    await_full_state=not lazy_load_members,
                 )
 
                 if batch:
                     state_at_timeline_end = (
                         await self._state_storage_controller.get_state_ids_for_event(
-                            batch.events[-1].event_id, state_filter=state_filter
+                            batch.events[-1].event_id,
+                            state_filter=state_filter,
+                            await_full_state=not lazy_load_members,
                         )
                     )
                 else:
                     # We can get here if the user has ignored the senders of all
                     # the recent events.
                     state_at_timeline_end = await self.get_state_at(
-                        room_id, stream_position=now_token, state_filter=state_filter
+                        room_id,
+                        stream_position=now_token,
+                        state_filter=state_filter,
+                        await_full_state=not lazy_load_members,
                     )
 
                 state_ids = _calculate_state(
@@ -1064,8 +1084,10 @@ class SyncHandler:
                                 (EventTypes.Member, member)
                                 for member in members_to_fetch
                             ),
+                            await_full_state=False,
                         )
 
+            # FIXME: `state_ids` may be missing memberships for partial state rooms.
             # At this point, if `lazy_load_members` is enabled, `state_ids` includes
             # the memberships of all event senders in the timeline. This is because we
             # may not have sent the memberships in a previous sync.