1 files changed, 11 insertions, 2 deletions
diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index ed2b03fad4..5c9f7a86f0 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -213,7 +213,15 @@ class FederationRemoteSendQueue(object):
     def get_current_token(self):
         return self.pos - 1
 
-    def get_replication_rows(self, token, limit):
+    def get_replication_rows(self, token, limit, federation_ack=None):
+        """
+        Args:
+            token (int)
+            limit (int)
+            federation_ack (int): Optional. The position where the worker is
+                explicitly acknowledged it has handled. Allows us to drop
+                data from before that point
+        """
         # TODO: Handle limit.
 
         # To handle restarts where we wrap around
@@ -224,7 +232,8 @@ class FederationRemoteSendQueue(object):
 
         # There should be only one reader, so lets delete everything its
         # acknowledged its seen.
-        self._clear_queue_before_pos(token)
+        if federation_ack:
+            self._clear_queue_before_pos(federation_ack)
 
         # Fetch changed presence
         keys = self.presence_changed.keys()