convert list of servers into a set

synapse/federation/federation_client.py

@@ -19,6 +19,7 @@
 import logging
 from typing import (
     TYPE_CHECKING,
+    AbstractSet,
     Awaitable,
     Callable,
     Collection,
@@ -110,9 +111,9 @@ class SendJoinResult:
     # True if 'state' elides non-critical membership events
     partial_state: bool
 
-    # If 'partial_state' is set, a list of the servers in the room (otherwise empty).
+    # If 'partial_state' is set, a set of the servers in the room (otherwise empty).
     # Always contains the server we joined off.
-    servers_in_room: List[str]
+    servers_in_room: AbstractSet[str]
 
 
 class FederationClient(FederationBase):
@@ -1153,30 +1154,32 @@ async def _execute(pdu: EventBase) -> None:
                     % (auth_chain_create_events,)
                 )
 
-            servers_in_room = response.servers_in_room
+            servers_in_room = None
+            if response.servers_in_room is not None:
+                servers_in_room = set(response.servers_in_room)
+
             if response.members_omitted:
                 if not servers_in_room:
                     raise InvalidResponseError(
                         "members_omitted was set, but no servers were listed in the room"
                     )
 
-                if destination not in servers_in_room:
-                    # `servers_in_room` is supposed to be a complete list.
-                    # Fix things up if the remote homeserver is badly behaved.
-                    servers_in_room = [destination] + servers_in_room
-
                 if not partial_state:
                     raise InvalidResponseError(
                         "members_omitted was set, but we asked for full state"
                     )
 
+                # `servers_in_room` is supposed to be a complete list.
+                # Fix things up in case the remote homeserver is badly behaved.
+                servers_in_room.add(destination)
+
             return SendJoinResult(
                 event=event,
                 state=signed_state,
                 auth_chain=signed_auth,
                 origin=destination,
                 partial_state=response.members_omitted,
-                servers_in_room=servers_in_room or [],
+                servers_in_room=servers_in_room or frozenset(),
             )
 
         # MSC3083 defines additional error codes for room joins.

synapse/handlers/federation.py

@@ -20,7 +20,17 @@
 import logging
 from enum import Enum
 from http import HTTPStatus
-from typing import TYPE_CHECKING, Dict, Iterable, List, Optional, Set, Tuple, Union
+from typing import (
+    TYPE_CHECKING,
+    AbstractSet,
+    Dict,
+    Iterable,
+    List,
+    Optional,
+    Set,
+    Tuple,
+    Union,
+)
 
 import attr
 from prometheus_client import Histogram
@@ -169,7 +179,7 @@ def __init__(self, hs: "HomeServer"):
         # A dictionary mapping room IDs to (initial destination, other destinations)
         # tuples.
         self._partial_state_syncs_maybe_needing_restart: Dict[
-            str, Tuple[Optional[str], StrCollection]
+            str, Tuple[Optional[str], AbstractSet[str]]
         ] = {}
         # A lock guarding the partial state flag for rooms.
         # When the lock is held for a given room, no other concurrent code may
@@ -1720,7 +1730,7 @@ async def _resume_partial_state_room_sync(self) -> None:
     def _start_partial_state_room_sync(
         self,
         initial_destination: Optional[str],
-        other_destinations: StrCollection,
+        other_destinations: AbstractSet[str],
         room_id: str,
     ) -> None:
         """Starts the background process to resync the state of a partial state room,
@@ -1802,7 +1812,7 @@ async def _sync_partial_state_room_wrapper() -> None:
     async def _sync_partial_state_room(
         self,
         initial_destination: Optional[str],
-        other_destinations: StrCollection,
+        other_destinations: AbstractSet[str],
         room_id: str,
     ) -> None:
         """Background process to resync the state of a partial-state room
@@ -1939,7 +1949,7 @@ async def _sync_partial_state_room(
 
 def _prioritise_destinations_for_partial_state_resync(
     initial_destination: Optional[str],
-    other_destinations: StrCollection,
+    other_destinations: AbstractSet[str],
     room_id: str,
 ) -> StrCollection:
     """Work out the order in which we should ask servers to resync events.

synapse/storage/controllers/state.py

@@ -573,7 +573,7 @@ async def get_current_hosts_in_room_or_partial_state_approximation(
             room_id
         )
         if hosts_at_join is None:
-            hosts_at_join = ()
+            hosts_at_join = frozenset()
 
         hosts_from_state = await self.stores.main.get_current_hosts_in_room(room_id)
 

synapse/storage/databases/main/room.py

@@ -18,14 +18,14 @@
 from enum import Enum
 from typing import (
     TYPE_CHECKING,
+    AbstractSet,
     Any,
     Awaitable,
     Collection,
     Dict,
     List,
     Mapping,
     Optional,
-    Sequence,
     Set,
     Tuple,
     Union,
@@ -108,7 +108,7 @@ class RoomSortOrder(Enum):
 @attr.s(slots=True, frozen=True, auto_attribs=True)
 class PartialStateResyncInfo:
     joined_via: Optional[str]
-    servers_in_room: List[str] = attr.ib(factory=list)
+    servers_in_room: Set[str] = attr.ib(factory=set)
 
 
 class RoomWorkerStore(CacheInvalidationWorkerStore):
@@ -1194,8 +1194,8 @@ def get_rooms_for_retention_period_in_range_txn(
 
     async def get_partial_state_servers_at_join(
         self, room_id: str
-    ) -> Optional[Sequence[str]]:
-        """Gets the list of servers in a partial state room at the time we joined it.
+    ) -> Optional[AbstractSet[str]]:
+        """Gets the set of servers in a partial state room at the time we joined it.
 
         Returns:
             The `servers_in_room` list from the `/send_join` response for partial state
@@ -1211,12 +1211,16 @@ async def get_partial_state_servers_at_join(
         return servers_in_room
 
     @cached(iterable=True)
-    async def _get_partial_state_servers_at_join(self, room_id: str) -> Sequence[str]:
-        return await self.db_pool.simple_select_onecol(
-            "partial_state_rooms_servers",
-            keyvalues={"room_id": room_id},
-            retcol="server_name",
-            desc="get_partial_state_servers_at_join",
+    async def _get_partial_state_servers_at_join(
+        self, room_id: str
+    ) -> AbstractSet[str]:
+        return frozenset(
+            await self.db_pool.simple_select_onecol(
+                "partial_state_rooms_servers",
+                keyvalues={"room_id": room_id},
+                retcol="server_name",
+                desc="get_partial_state_servers_at_join",
+            )
         )
 
     async def get_partial_state_room_resync_info(
@@ -1261,7 +1265,7 @@ async def get_partial_state_room_resync_info(
                 # partial-joined between the two SELECTs, but this is unlikely to happen
                 # in practice.)
                 continue
-            entry.servers_in_room.append(server_name)
+            entry.servers_in_room.add(server_name)
 
         return room_servers
 
@@ -1951,7 +1955,7 @@ async def upsert_room_on_join(
     async def store_partial_state_room(
         self,
         room_id: str,
-        servers: Collection[str],
+        servers: AbstractSet[str],
         device_lists_stream_id: int,
         joined_via: str,
     ) -> None:
@@ -1986,7 +1990,7 @@ def _store_partial_state_room_txn(
         self,
         txn: LoggingTransaction,
         room_id: str,
-        servers: Collection[str],
+        servers: AbstractSet[str],
         device_lists_stream_id: int,
         joined_via: str,
     ) -> None:

tests/handlers/test_federation.py

@@ -656,7 +656,7 @@ def test_failed_partial_join_is_clean(self) -> None:
                         EVENT_INVITATION_MEMBERSHIP,
                     ],
                     partial_state=True,
-                    servers_in_room=["example.com"],
+                    servers_in_room={"example.com"},
                 )
             )
         )

tests/handlers/test_room_member.py

@@ -171,7 +171,7 @@ def test_remote_joins_contribute_to_rate_limit(self) -> None:
                     state=[create_event],
                     auth_chain=[create_event],
                     partial_state=False,
-                    servers_in_room=[],
+                    servers_in_room=frozenset(),
                 )
             )
         )