1 files changed, 5 insertions, 0 deletions
diff --git a/synapse/federation/transaction_queue.py b/synapse/federation/transaction_queue.py
index 90235ff098..c802dd67a3 100644
--- a/synapse/federation/transaction_queue.py
+++ b/synapse/federation/transaction_queue.py
@@ -99,7 +99,12 @@ class TransactionQueue(object):
         # destination -> list of tuple(failure, deferred)
         self.pending_failures_by_dest = {}
 
+        # destination -> stream_id of last successfully sent to-device message.
+        # NB: may be a long or an int.
         self.last_device_stream_id_by_dest = {}
+
+        # destination -> stream_id of last successfully sent device list
+        # update.
         self.last_device_list_stream_id_by_dest = {}
 
         # HACK to get unique tx id