1 files changed, 6 insertions, 0 deletions
diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py
index 3c051dabc4..b72bb0ff02 100644
--- a/synapse/util/caches/stream_change_cache.py
+++ b/synapse/util/caches/stream_change_cache.py
@@ -121,3 +121,9 @@ class StreamChangeCache(object):
                 k, r = self._cache.popitem()
                 self._earliest_known_stream_pos = max(k, self._earliest_known_stream_pos)
                 self._entity_to_key.pop(r, None)
+
+    def get_max_pos_of_last_change(self, entity):
+        """Returns an upper bound of the stream id of the last change to an
+        entity.
+        """
+        return self._entity_to_key.get(entity, self._earliest_known_stream_pos)