Remove stream ordering from Metadata dict (#8452)

There's no need for it to be in the dict as well as the events table. Instead,
we store it in a separate attribute in the EventInternalMetadata object, and
populate that on load.

This means that we can rely on it being correctly populated for any event which
has been persited to the database.

3 files changed, 13 insertions, 7 deletions

diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py

index 1a8144405a..5ac2fc5656 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -3008,6 +3008,9 @@ class FederationHandler(BaseHandler):
         elif event.internal_metadata.is_outlier():
             return
 
+        # the event has been persisted so it should have a stream ordering.
+        assert event.internal_metadata.stream_ordering
+
         event_pos = PersistedEventPosition(
             self._instance_name, event.internal_metadata.stream_ordering
         )
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py

index ee271e85e5..00513fbf37 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -682,7 +682,9 @@ class EventCreationHandler:
                     event.event_id,
                     prev_event.event_id,
                 )
-                return await self.store.get_stream_id_for_event(prev_event.event_id)
+                # we know it was persisted, so must have a stream ordering
+                assert prev_event.internal_metadata.stream_ordering
+                return prev_event.internal_metadata.stream_ordering
 
         return await self.handle_new_client_event(
             requester=requester, event=event, context=context, ratelimit=ratelimit
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py

index 567a14bd0a..13b749b7cb 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -194,8 +194,9 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
         )
         if duplicate is not None:
             # Discard the new event since this membership change is a no-op.
-            _, stream_id = await self.store.get_event_ordering(duplicate.event_id)
-            return duplicate.event_id, stream_id
+            # we know it was persisted, so must have a stream ordering.
+            assert duplicate.internal_metadata.stream_ordering
+            return duplicate.event_id, duplicate.internal_metadata.stream_ordering
 
         prev_state_ids = await context.get_prev_state_ids()
 
@@ -441,12 +442,12 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
                 same_membership = old_membership == effective_membership_state
                 same_sender = requester.user.to_string() == old_state.sender
                 if same_sender and same_membership and same_content:
-                    _, stream_id = await self.store.get_event_ordering(
-                        old_state.event_id
-                    )
+                    # duplicate event.
+                    # we know it was persisted, so must have a stream ordering.
+                    assert old_state.internal_metadata.stream_ordering
                     return (
                         old_state.event_id,
-                        stream_id,
+                        old_state.internal_metadata.stream_ordering,
                     )
 
             if old_membership in ["ban", "leave"] and action == "kick":