WIP: Connect state_chain to prev_event and the batch to the state_chain so everyhting is valid

We are going to lose the benefit of keeping the join noise out of the timeline.
And will probably have to hide "historical" state on the client.

Author: MadLittleMods

synapse/handlers/room_batch.py

@@ -153,6 +153,7 @@ async def persist_state_events_at_start(
         self,
         state_events_at_start: List[JsonDict],
         room_id: str,
+        initial_prev_event_ids: List[str],
         initial_state_event_ids: List[str],
         app_service_requester: Requester,
     ) -> List[str]:
@@ -178,10 +179,8 @@ async def persist_state_events_at_start(
         state_event_ids_at_start = []
         state_event_ids = initial_state_event_ids.copy()
 
-        # Make the state events float off on their own by specifying no
-        # prev_events for the first one in the chain so we don't have a bunch of
-        # `@mxid joined the room` noise between each batch.
-        prev_event_ids_for_state_chain: List[str] = []
+        # TODO: Here
+        prev_event_ids_for_state_chain: List[str] = initial_prev_event_ids
 
         for index, state_event in enumerate(state_events_at_start):
             assert_params_in_dict(
@@ -269,6 +268,7 @@ async def persist_historical_events(
         events_to_create: List[JsonDict],
         room_id: str,
         inherited_depth: int,
+        state_chain_event_id_to_connect_to: str,
         initial_state_event_ids: List[str],
         app_service_requester: Requester,
     ) -> List[str]:
@@ -301,10 +301,8 @@ async def persist_historical_events(
         # We expect the last event in a historical batch to be an batch event
         assert events_to_create[-1]["type"] == EventTypes.MSC2716_BATCH
 
-        # Make the historical event chain float off on its own by specifying no
-        # prev_events for the first event in the chain which causes the HS to
-        # ask for the state at the start of the batch later.
-        prev_event_ids: List[str] = []
+        # TODO: Here
+        prev_event_ids: List[str] = [state_chain_event_id_to_connect_to]
 
         event_ids = []
         events_to_persist = []
@@ -390,6 +388,7 @@ async def handle_batch_of_events(
         events_to_create: List[JsonDict],
         room_id: str,
         batch_id_to_connect_to: str,
+        state_chain_event_id_to_connect_to: str,
         inherited_depth: int,
         initial_state_event_ids: List[str],
         app_service_requester: Requester,
@@ -458,6 +457,7 @@ async def handle_batch_of_events(
             events_to_create=events_to_create,
             room_id=room_id,
             inherited_depth=inherited_depth,
+            state_chain_event_id_to_connect_to=state_chain_event_id_to_connect_to,
             initial_state_event_ids=initial_state_event_ids,
             app_service_requester=app_service_requester,
         )

synapse/rest/client/room_batch.py

@@ -153,6 +153,7 @@ async def on_POST(
                 await self.room_batch_handler.persist_state_events_at_start(
                     state_events_at_start=body["state_events_at_start"],
                     room_id=room_id,
+                    initial_prev_event_ids=prev_event_ids_from_query,
                     initial_state_event_ids=state_event_ids,
                     app_service_requester=requester,
                 )
@@ -222,6 +223,8 @@ async def on_POST(
             room_id=room_id,
             batch_id_to_connect_to=batch_id_to_connect_to,
             inherited_depth=inherited_depth,
+            # Connect the historical batch to the state chain
+            state_chain_event_id_to_connect_to=state_event_ids_at_start[-1],
             initial_state_event_ids=state_event_ids,
             app_service_requester=requester,
         )

tests/handlers/test_federation_event.py

@@ -1041,9 +1041,9 @@ async def get_event(destination: str, event_id: str, timeout=None):
                 # It all works when I add a prev_event for the floating
                 # insertion event but the event no longer floats.
                 # It's able to resolve state at the prev_events though.
-                # prev_event_ids=[event_before.event_id],
-                allow_no_prev_events=True,
-                prev_event_ids=[],
+                prev_event_ids=[event_before.event_id],
+                # allow_no_prev_events=True,
+                # prev_event_ids=[],
                 auth_event_ids=historical_base_auth_event_ids,
                 state_event_ids=historical_state_event_ids,
                 depth=inherited_depth,