Send device list updates to application services (MSC3202) - part 1 (#11881)

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

synapse/handlers/sync.py

@@ -13,17 +13,7 @@
 # limitations under the License.
 import itertools
 import logging
-from typing import (
-    TYPE_CHECKING,
-    Any,
-    Collection,
-    Dict,
-    FrozenSet,
-    List,
-    Optional,
-    Set,
-    Tuple,
-)
+from typing import TYPE_CHECKING, Any, Dict, FrozenSet, List, Optional, Set, Tuple
 
 import attr
 from prometheus_client import Counter
@@ -41,6 +31,7 @@ from synapse.storage.databases.main.event_push_actions import NotifCounts
 from synapse.storage.roommember import MemberSummary
 from synapse.storage.state import StateFilter
 from synapse.types import (
+    DeviceListUpdates,
     JsonDict,
     MutableStateMap,
     Requester,
@@ -184,21 +175,6 @@ class GroupsSyncResult:
         return bool(self.join or self.invite or self.leave)
 
 
-@attr.s(slots=True, frozen=True, auto_attribs=True)
-class DeviceLists:
-    """
-    Attributes:
-        changed: List of user_ids whose devices may have changed
-        left: List of user_ids whose devices we no longer track
-    """
-
-    changed: Collection[str]
-    left: Collection[str]
-
-    def __bool__(self) -> bool:
-        return bool(self.changed or self.left)
-
-
 @attr.s(slots=True, auto_attribs=True)
 class _RoomChanges:
     """The set of room entries to include in the sync, plus the set of joined
@@ -240,7 +216,7 @@ class SyncResult:
     knocked: List[KnockedSyncResult]
     archived: List[ArchivedSyncResult]
     to_device: List[JsonDict]
-    device_lists: DeviceLists
+    device_lists: DeviceListUpdates
     device_one_time_keys_count: JsonDict
     device_unused_fallback_key_types: List[str]
     groups: Optional[GroupsSyncResult]
@@ -1264,8 +1240,8 @@ class SyncHandler:
         newly_joined_or_invited_or_knocked_users: Set[str],
         newly_left_rooms: Set[str],
         newly_left_users: Set[str],
-    ) -> DeviceLists:
-        """Generate the DeviceLists section of sync
+    ) -> DeviceListUpdates:
+        """Generate the DeviceListUpdates section of sync
 
         Args:
             sync_result_builder
@@ -1383,9 +1359,11 @@ class SyncHandler:
                 if any(e.room_id in joined_rooms for e in entries):
                     newly_left_users.discard(user_id)
 
-            return DeviceLists(changed=users_that_have_changed, left=newly_left_users)
+            return DeviceListUpdates(
+                changed=users_that_have_changed, left=newly_left_users
+            )
         else:
-            return DeviceLists(changed=[], left=[])
+            return DeviceListUpdates()
 
     async def _generate_sync_entry_for_to_device(
         self, sync_result_builder: "SyncResultBuilder"