Return read-only collections from @cached methods

changelog.d/13755.misc

@@ -0,0 +1 @@
+Re-type hint some collections as read-only.

synapse/app/phone_stats_home.py

@@ -15,7 +15,7 @@
 import math
 import resource
 import sys
-from typing import TYPE_CHECKING, List, Sized, Tuple
+from typing import TYPE_CHECKING, List, Mapping, Sized, Tuple
 
 from prometheus_client import Gauge
 
@@ -194,7 +194,7 @@ def performance_stats_init() -> None:
     @wrap_as_background_process("generate_monthly_active_users")
     async def generate_monthly_active_users() -> None:
         current_mau_count = 0
-        current_mau_count_by_service = {}
+        current_mau_count_by_service: Mapping[str, int] = {}
         reserved_users: Sized = ()
         store = hs.get_datastores().main
         if hs.config.server.limit_usage_by_mau or hs.config.server.mau_stats_only:

synapse/config/room_directory.py

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Any, List
+from typing import Any, Collection
 
 from matrix_common.regex import glob_to_regex
 
@@ -70,7 +70,7 @@ def is_alias_creation_allowed(self, user_id: str, room_id: str, alias: str) -> b
         return False
 
     def is_publishing_room_allowed(
-        self, user_id: str, room_id: str, aliases: List[str]
+        self, user_id: str, room_id: str, aliases: Collection[str]
     ) -> bool:
         """Checks if the given user is allowed to publish the room
 
@@ -122,7 +122,7 @@ def __init__(self, option_name: str, rule: JsonDict):
         except Exception as e:
             raise ConfigError("Failed to parse glob into regex") from e
 
-    def matches(self, user_id: str, room_id: str, aliases: List[str]) -> bool:
+    def matches(self, user_id: str, room_id: str, aliases: Collection[str]) -> bool:
         """Tests if this rule matches the given user_id, room_id and aliases.
 
         Args:

synapse/events/builder.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union
+from typing import TYPE_CHECKING, Any, Collection, Dict, List, Optional, Tuple, Union
 
 import attr
 from signedjson.types import SigningKey
@@ -103,7 +103,7 @@ def is_state(self) -> bool:
 
     async def build(
         self,
-        prev_event_ids: List[str],
+        prev_event_ids: Collection[str],
         auth_event_ids: Optional[List[str]],
         depth: Optional[int] = None,
     ) -> EventBase:
@@ -136,7 +136,7 @@ async def build(
 
         format_version = self.room_version.event_format
         # The types of auth/prev events changes between event versions.
-        prev_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
+        prev_events: Union[Collection[str], List[Tuple[str, Dict[str, str]]]]
         auth_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
         if format_version == EventFormatVersions.ROOM_V1_V2:
             auth_events = await self._store.add_event_hashes(auth_event_ids)

synapse/federation/federation_server.py

@@ -23,6 +23,7 @@
     Collection,
     Dict,
     List,
+    Mapping,
     Optional,
     Tuple,
     Union,
@@ -1506,7 +1507,7 @@ async def on_query(self, query_type: str, args: dict) -> JsonDict:
 def _get_event_ids_for_partial_state_join(
     join_event: EventBase,
     prev_state_ids: StateMap[str],
-    summary: Dict[str, MemberSummary],
+    summary: Mapping[str, MemberSummary],
 ) -> Collection[str]:
     """Calculate state to be returned in a partial_state send_join
 

synapse/handlers/directory.py

@@ -14,7 +14,7 @@
 
 import logging
 import string
-from typing import TYPE_CHECKING, Iterable, List, Optional
+from typing import TYPE_CHECKING, Iterable, List, Optional, Sequence
 
 from typing_extensions import Literal
 
@@ -485,6 +485,7 @@ async def edit_published_room_list(
                 )
             )
             if canonical_alias:
+                room_aliases = list(room_aliases)
                 room_aliases.append(canonical_alias)
 
             if not self.config.roomdirectory.is_publishing_room_allowed(
@@ -528,7 +529,7 @@ async def edit_published_appservice_room_list(
 
     async def get_aliases_for_room(
         self, requester: Requester, room_id: str
-    ) -> List[str]:
+    ) -> Sequence[str]:
         """
         Get a list of the aliases that currently point to this room on this server
         """

synapse/handlers/receipts.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple
+from typing import TYPE_CHECKING, Iterable, List, Optional, Sequence, Tuple
 
 from synapse.api.constants import EduTypes, ReceiptTypes
 from synapse.appservice import ApplicationService
@@ -189,7 +189,7 @@ def __init__(self, hs: "HomeServer"):
 
     @staticmethod
     def filter_out_private_receipts(
-        rooms: List[JsonDict], user_id: str
+        rooms: Sequence[JsonDict], user_id: str
     ) -> List[JsonDict]:
         """
         Filters a list of serialized receipts (as returned by /sync and /initialSync)

synapse/handlers/room.py

@@ -1927,6 +1927,6 @@ async def shutdown_room(
         return {
             "kicked_users": kicked_users,
             "failed_to_kick_users": failed_to_kick_users,
-            "local_aliases": aliases_for_room,
+            "local_aliases": list(aliases_for_room),
             "new_room_id": new_room_id,
         }

synapse/handlers/sync.py

@@ -1493,7 +1493,7 @@ async def generate_sync_result(
             one_time_keys_count = await self.store.count_e2e_one_time_keys(
                 user_id, device_id
             )
-            unused_fallback_key_types = (
+            unused_fallback_key_types = list(
                 await self.store.get_e2e_unused_fallback_key_types(user_id, device_id)
             )
 
@@ -1695,7 +1695,7 @@ async def _generate_sync_entry_for_to_device(
 
     async def _generate_sync_entry_for_account_data(
         self, sync_result_builder: "SyncResultBuilder"
-    ) -> Dict[str, Dict[str, JsonDict]]:
+    ) -> Mapping[str, Mapping[str, JsonDict]]:
         """Generates the account data portion of the sync response.
 
         Account data (called "Client Config" in the spec) can be set either globally
@@ -1730,6 +1730,7 @@ async def _generate_sync_entry_for_account_data(
             )
 
             if push_rules_changed:
+                global_account_data = dict(global_account_data)
                 global_account_data["m.push_rules"] = await self.push_rules_for_user(
                     sync_config.user
                 )
@@ -1739,6 +1740,7 @@ async def _generate_sync_entry_for_account_data(
                 account_data_by_room,
             ) = await self.store.get_account_data_for_user(sync_config.user.to_string())
 
+            global_account_data = dict(global_account_data)
             global_account_data["m.push_rules"] = await self.push_rules_for_user(
                 sync_config.user
             )
@@ -1815,7 +1817,7 @@ async def _generate_sync_entry_for_presence(
     async def _generate_sync_entry_for_rooms(
         self,
         sync_result_builder: "SyncResultBuilder",
-        account_data_by_room: Dict[str, Dict[str, JsonDict]],
+        account_data_by_room: Mapping[str, Mapping[str, JsonDict]],
     ) -> Tuple[AbstractSet[str], AbstractSet[str], AbstractSet[str], AbstractSet[str]]:
         """Generates the rooms portion of the sync response. Populates the
         `sync_result_builder` with the result.
@@ -2284,8 +2286,8 @@ async def _generate_room_entry(
         sync_result_builder: "SyncResultBuilder",
         room_builder: "RoomSyncResultBuilder",
         ephemeral: List[JsonDict],
-        tags: Optional[Dict[str, Dict[str, Any]]],
-        account_data: Dict[str, JsonDict],
+        tags: Optional[Mapping[str, Mapping[str, Any]]],
+        account_data: Mapping[str, JsonDict],
         always_include: bool = False,
     ) -> None:
         """Populates the `joined` and `archived` section of `sync_result_builder`