1 files changed, 23 insertions, 9 deletions
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index c8858b22dd..dace9b606f 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -31,14 +31,20 @@ from typing import (
 import attr
 from prometheus_client import Counter
 
-from synapse.api.constants import EventTypes, Membership
+from synapse.api.constants import EventContentFields, EventTypes, Membership
 from synapse.api.filtering import FilterCollection
 from synapse.api.presence import UserPresenceState
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.events import EventBase
 from synapse.handlers.relations import BundledAggregations
 from synapse.logging.context import current_context
-from synapse.logging.opentracing import SynapseTags, log_kv, set_tag, start_active_span
+from synapse.logging.opentracing import (
+    SynapseTags,
+    log_kv,
+    set_tag,
+    start_active_span,
+    trace,
+)
 from synapse.push.clientformat import format_push_rules_for_user
 from synapse.storage.databases.main.event_push_actions import RoomNotifCounts
 from synapse.storage.databases.main.roommember import extract_heroes_from_room_summary
@@ -1528,10 +1534,12 @@ class SyncHandler:
             #
             # If we don't have that info cached then we get all the users that
             # share a room with our user and check if those users have changed.
-            changed_users = self.store.get_cached_device_list_changes(
+            cache_result = self.store.get_cached_device_list_changes(
                 since_token.device_list_key
             )
-            if changed_users is not None:
+            if cache_result.hit:
+                changed_users = cache_result.entities
+
                 result = await self.store.get_rooms_for_users(changed_users)
 
                 for changed_user_id, entries in result.items():
@@ -1584,6 +1592,7 @@ class SyncHandler:
         else:
             return DeviceListUpdates()
 
+    @trace
     async def _generate_sync_entry_for_to_device(
         self, sync_result_builder: "SyncResultBuilder"
     ) -> None:
@@ -1603,11 +1612,16 @@ class SyncHandler:
             )
 
             for message in messages:
-                # We pop here as we shouldn't be sending the message ID down
-                # `/sync`
-                message_id = message.pop("message_id", None)
-                if message_id:
-                    set_tag(SynapseTags.TO_DEVICE_MESSAGE_ID, message_id)
+                log_kv(
+                    {
+                        "event": "to_device_message",
+                        "sender": message["sender"],
+                        "type": message["type"],
+                        EventContentFields.TO_DEVICE_MSGID: message["content"].get(
+                            EventContentFields.TO_DEVICE_MSGID
+                        ),
+                    }
+                )
 
             logger.debug(
                 "Returning %d to-device messages between %d and %d (current token: %d)",