Add a new method to enqueue the device messages rather than sending a dummy EDU

synapse/federation/federation_client.py

@@ -137,6 +137,12 @@ class FederationClient(FederationBase):
         self._transaction_queue.enqueue_edu(edu)
         return defer.succeed(None)
 
+    @log_function
+    def send_device_messages(self, destination):
+        """Sends the device messages in the local database to the remote
+        destination"""
+        self._transaction_queue.enqueue_device_messages(destination)
+
     @log_function
     def send_failure(self, failure, destination):
         self._transaction_queue.enqueue_failure(failure, destination)

synapse/federation/transaction_queue.py

@@ -157,6 +157,17 @@ class TransactionQueue(object):
             self._attempt_new_transaction, destination
         )
 
+    def enqueue_device_messages(self, destination):
+        if destination == self.server_name or destination == "localhost":
+            return
+
+        if not self.can_send_to(destination):
+            return
+
+        preserve_context_over_fn(
+            self._attempt_new_transaction, destination
+        )
+
     @defer.inlineCallbacks
     def _attempt_new_transaction(self, destination):
         yield run_on_reactor()

synapse/handlers/devicemessage.py

@@ -112,10 +112,6 @@ class DeviceMessageHandler(object):
         )
 
         for destination in remote_messages.keys():
-            # Hack to send make synapse send a federation transaction
-            # to the remote servers.
-            self.federation.send_edu(
-                destination=destination,
-                edu_type="m.ping",
-                content={},
-            )
+            # Enqueue a new federation transaction to send the new
+            # device messages to each remote destination.
+            self.federation.send_device_messages(destination)