Factor out a separate `EventContext.for_outlier` (#10883)

Constructing an EventContext for an outlier is actually really simple, and
there's no sense in going via an `async` method in the `StateHandler`.

This also means that we can resolve a bunch of FIXMEs.

2 files changed, 6 insertions, 10 deletions

diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index a03d77dffd..0befe9ce43 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -624,7 +624,7 @@ class FederationHandler(BaseHandler):
         # in the invitee's sync stream. It is stripped out for all other local users.
         event.unsigned["knock_room_state"] = stripped_room_state["knock_state_events"]
 
-        context = await self.state_handler.compute_event_context(event)
+        context = EventContext.for_outlier()
         stream_id = await self._federation_event_handler.persist_events_and_notify(
             event.room_id, [(event, context)]
         )
@@ -814,7 +814,7 @@ class FederationHandler(BaseHandler):
             )
         )
 
-        context = await self.state_handler.compute_event_context(event)
+        context = EventContext.for_outlier()
         await self._federation_event_handler.persist_events_and_notify(
             event.room_id, [(event, context)]
         )
@@ -843,7 +843,7 @@ class FederationHandler(BaseHandler):
 
         await self.federation_client.send_leave(host_list, event)
 
-        context = await self.state_handler.compute_event_context(event)
+        context = EventContext.for_outlier()
         stream_id = await self._federation_event_handler.persist_events_and_notify(
             event.room_id, [(event, context)]
         )
@@ -1115,8 +1115,7 @@ class FederationHandler(BaseHandler):
         events_to_context = {}
         for e in itertools.chain(auth_events, state):
             e.internal_metadata.outlier = True
-            ctx = await self.state_handler.compute_event_context(e)
-            events_to_context[e.event_id] = ctx
+            events_to_context[e.event_id] = EventContext.for_outlier()
 
         event_map = {
             e.event_id: e for e in itertools.chain(auth_events, state, [event])
diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py
index 3b95beeb08..10b3fdc222 100644
--- a/synapse/handlers/federation_event.py
+++ b/synapse/handlers/federation_event.py
@@ -1221,7 +1221,7 @@ class FederationEventHandler:
         async def prep(ev_info: _NewEventInfo) -> EventContext:
             event = ev_info.event
             with nested_logging_context(suffix=event.event_id):
-                res = await self._state_handler.compute_event_context(event)
+                res = EventContext.for_outlier()
                 res = await self._check_event_auth(
                     origin,
                     event,
@@ -1540,10 +1540,7 @@ class FederationEventHandler:
                             event.event_id,
                             auth_event.event_id,
                         )
-                        missing_auth_event_context = (
-                            await self._state_handler.compute_event_context(auth_event)
-                        )
-
+                        missing_auth_event_context = EventContext.for_outlier()
                         missing_auth_event_context = await self._check_event_auth(
                             origin,
                             auth_event,