make user signatures a separate stream

synapse/storage/data_stores/main/devices.py

@@ -543,20 +543,9 @@ class DeviceWorkerStore(SQLBaseStore):
             LEFT JOIN device_lists_outbound_pokes USING (stream_id, user_id, device_id)
             WHERE ? < stream_id AND stream_id <= ?
             GROUP BY user_id, destination
-            UNION
-            SELECT MAX(stream_id) AS stream_id, from_user_id AS user_id, NULL AS destination
-            FROM user_signature_stream
-            WHERE ? < stream_id AND stream_id <= ?
-            GROUP BY user_id
         """
         return self._execute(
-            "get_all_device_list_changes_for_remotes",
-            None,
-            sql,
-            from_key,
-            to_key,
-            from_key,
-            to_key,
+            "get_all_device_list_changes_for_remotes", None, sql, from_key, to_key
         )
 
     @cached(max_entries=10000)

synapse/storage/data_stores/main/end_to_end_keys.py

@@ -315,6 +315,30 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
             from_user_id,
         )
 
+    def get_all_user_signature_changes_for_remotes(self, from_key, to_key):
+        """Return a list of changes from the user signature stream to notify remotes.
+        Note that the user signature stream represents when a user signs their
+        device with their user-signing key, which is not published to other
+        users or servers, so no `destination` is needed in the returned
+        list. However, this is needed to poke workers.
+
+        Args:
+            from_key (int): the stream ID to start at (exclusive)
+            to_key (int): the stream ID to end at (inclusive)
+
+        Returns:
+            Deferred[list[(int,str)]] a list of `(stream_id, user_id)`
+        """
+        sql = """
+            SELECT MAX(stream_id) AS stream_id, from_user_id AS user_id
+            FROM user_signature_stream
+            WHERE ? < stream_id AND stream_id <= ?
+            GROUP BY user_id
+        """
+        return self._execute(
+            "get_all_user_signature_changes_for_remotes", None, sql, from_key, to_key
+        )
+
 
 class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
     def set_e2e_device_keys(self, user_id, device_id, time_now, device_keys):