1 files changed, 3 insertions, 0 deletions
diff --git a/synapse/replication/slave/storage/devices.py b/synapse/replication/slave/storage/devices.py
index 01a4f85884..23b1650e41 100644
--- a/synapse/replication/slave/storage/devices.py
+++ b/synapse/replication/slave/storage/devices.py
@@ -72,6 +72,9 @@ class SlavedDeviceStore(EndToEndKeyWorkerStore, DeviceWorkerStore, BaseSlavedSto
 
     def _invalidate_caches_for_devices(self, token, rows):
         for row in rows:
+            # The entities are either user IDs (starting with '@') whose devices
+            # have changed, or remote servers that we need to tell about
+            # changes.
             if row.entity.startswith("@"):
                 self._device_list_stream_cache.entity_has_changed(row.entity, token)
                 self.get_cached_devices_for_user.invalidate((row.entity,))