1 files changed, 57 insertions, 0 deletions
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index b73401bc26..ed372e2fc4 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -302,6 +302,41 @@ class DeviceWorkerStore(SQLBaseStore):
         """
         txn.execute(sql, (destination, stream_id))
 
+    @defer.inlineCallbacks
+    def add_user_signature_change_to_streams(self, from_user_id, user_ids):
+        """Persist that a user has made new signatures
+
+        Args:
+            from_user_id (str): the user who made the signatures
+            user_ids (list[str]): the users who were signed
+        """
+
+        with self._device_list_id_gen.get_next() as stream_id:
+            yield self.runInteraction(
+                "add_user_sig_change_to_streams",
+                self._add_user_signature_change_txn,
+                from_user_id,
+                user_ids,
+                stream_id,
+            )
+        defer.returnValue(stream_id)
+
+    def _add_user_signature_change_txn(self, txn, from_user_id, user_ids, stream_id):
+        txn.call_after(
+            self._user_signature_stream_cache.entity_has_changed,
+            from_user_id,
+            stream_id,
+        )
+        self._simple_insert_txn(
+            txn,
+            "user_signature_stream",
+            values={
+                "stream_id": stream_id,
+                "from_user_id": from_user_id,
+                "user_ids": json.dumps(user_ids),
+            },
+        )
+
     def get_device_stream_token(self):
         return self._device_list_id_gen.get_current_token()
 
@@ -440,6 +475,28 @@ class DeviceWorkerStore(SQLBaseStore):
             "get_users_whose_devices_changed", _get_users_whose_devices_changed_txn
         )
 
+    @defer.inlineCallbacks
+    def get_users_whose_signatures_changed(self, user_id, from_key):
+        """Get the users who have new cross-signing signatures made by `user_id` since
+        `from_key`.
+
+        Args:
+            user_id (str): the user who made the signatures
+            from_key (str): The device lists stream token
+        """
+        from_key = int(from_key)
+        if self._user_signature_stream_cache.has_entity_changed(user_id, from_key):
+            sql = """
+                SELECT DISTINCT user_ids FROM user_signature_stream
+                WHERE from_user_id = ? AND stream_id > ?
+            """
+            rows = yield self._execute(
+                "get_users_whose_signatures_changed", None, sql, user_id, from_key
+            )
+            defer.returnValue(set(user for row in rows for user in json.loads(row[0])))
+        else:
+            defer.returnValue(set())
+
     def get_all_device_list_changes_for_remotes(self, from_key, to_key):
         """Return a list of `(stream_id, user_id, destination)` which is the
         combined list of changes to devices, and which destinations need to be