Resync remote device list when detected as stale. (#6786)

1 files changed, 8 insertions, 2 deletions

diff --git a/synapse/handlers/devicemessage.py b/synapse/handlers/devicemessage.py
index 5c5fe77be2..05c4b3eec0 100644
--- a/synapse/handlers/devicemessage.py
+++ b/synapse/handlers/devicemessage.py
@@ -21,6 +21,7 @@ from canonicaljson import json
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
+from synapse.logging.context import run_in_background
 from synapse.logging.opentracing import (
     get_active_span_text_map,
     log_kv,
@@ -48,6 +49,8 @@ class DeviceMessageHandler(object):
             "m.direct_to_device", self.on_direct_to_device_edu
         )
 
+        self._device_list_updater = hs.get_device_handler().device_list_updater
+
     @defer.inlineCallbacks
     def on_direct_to_device_edu(self, origin, content):
         local_messages = {}
@@ -134,8 +137,11 @@ class DeviceMessageHandler(object):
                 unknown_devices,
             )
             yield self.store.mark_remote_user_device_cache_as_stale(sender_user_id)
-            # TODO: Poke something to start trying to refetch user's
-            # keys.
+
+            # Immediately attempt a resync in the background
+            run_in_background(
+                self._device_list_updater.user_device_resync, sender_user_id
+            )
 
     @defer.inlineCallbacks
     def send_device_message(self, sender_user_id, message_type, messages):