From dbe7892e03e2e0e6a50c54109c30b22fe4194894 Mon Sep 17 00:00:00 2001 From: Mark Haines Date: Mon, 14 Dec 2015 15:09:41 +0000 Subject: [PATCH] Fix a race between started/stopped stream --- synapse/handlers/events.py | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py index fe300433e6ce..576d77e0e7ca 100644 --- a/synapse/handlers/events.py +++ b/synapse/handlers/events.py @@ -69,7 +69,12 @@ def started_stream(self, user): A deferred that completes once their presence has been updated. """ if user not in self._streams_per_user: - self._streams_per_user[user] = 0 + # Make sure we set the streams per user to 1 here rather than + # setting it to zero and incrementing the value below. + # Otherwise this may race with stopped_stream causing the + # user to be erased from the map before we have a chance + # to increment it. + self._streams_per_user[user] = 1 if user in self._stop_timer_per_user: try: self.clock.cancel_call_later( @@ -79,8 +84,8 @@ def started_stream(self, user): logger.exception("Failed to cancel event timer") else: yield started_user_eventstream(self.distributor, user) - - self._streams_per_user[user] += 1 + else: + self._streams_per_user[user] += 1 def stopped_stream(self, user): """If there are no streams for a user this starts a timer that will