Replace usage of get_domains_from_state with get_current_hosts_in_room

synapse/handlers/federation.py

@@ -99,37 +99,6 @@
 )
 
 
-def get_domains_from_state(state: StateMap[EventBase]) -> List[Tuple[str, int]]:
-    """Get joined domains from state
-
-    Args:
-        state: State map from type/state key to event.
-
-    Returns:
-        Returns a list of servers with the lowest depth of their joins.
-            Sorted by lowest depth first.
-    """
-    joined_users = [
-        (state_key, int(event.depth))
-        for (e_type, state_key), event in state.items()
-        if e_type == EventTypes.Member and event.membership == Membership.JOIN
-    ]
-
-    joined_domains: Dict[str, int] = {}
-    for u, d in joined_users:
-        try:
-            dom = get_domain_from_id(u)
-            old_d = joined_domains.get(dom)
-            if old_d:
-                joined_domains[dom] = min(d, old_d)
-            else:
-                joined_domains[dom] = d
-        except Exception:
-            pass
-
-    return sorted(joined_domains.items(), key=lambda d: d[1])
-
-
 class _BackfillPointType(Enum):
     # a regular backwards extremity (ie, an event which we don't yet have, but which
     # is referred to by other events in the DAG)
@@ -427,17 +396,11 @@ async def _maybe_backfill_inner(
         )
 
         # Now we need to decide which hosts to hit first.
-
-        # First we try hosts that are already in the room
+        # First we try hosts that are already in the room.
         # TODO: HEURISTIC ALERT.
-
-        curr_state = await self._storage_controllers.state.get_current_state(room_id)
-
-        curr_domains = get_domains_from_state(curr_state)
-
-        likely_domains = [
-            domain for domain, depth in curr_domains if domain != self.server_name
-        ]
+        likely_domains = (
+            await self._storage_controllers.state.get_current_hosts_in_room(room_id)
+        )
 
         async def try_backfill(domains: List[str]) -> bool:
             # TODO: Should we try multiple of these at a time?

synapse/handlers/room.py

@@ -60,7 +60,6 @@
 from synapse.events import EventBase
 from synapse.events.utils import copy_and_fixup_power_levels_contents
 from synapse.federation.federation_client import InvalidResponseError
-from synapse.handlers.federation import get_domains_from_state
 from synapse.handlers.relations import BundledAggregations
 from synapse.module_api import NOT_SPAM
 from synapse.rest.admin._base import assert_user_is_admin
@@ -1459,14 +1458,9 @@ async def get_event_for_timestamp(
                 timestamp,
             )
 
-            # Find other homeservers from the given state in the room
-            curr_state = await self._storage_controllers.state.get_current_state(
-                room_id
+            likely_domains = (
+                await self._storage_controllers.state.get_current_hosts_in_room(room_id)
             )
-            curr_domains = get_domains_from_state(curr_state)
-            likely_domains = [
-                domain for domain, depth in curr_domains if domain != self.server_name
-            ]
 
             # Loop through each homeserver candidate until we get a succesful response
             for domain in likely_domains: