From f76d407ef3d2f6c18a568eff965e12e794105a7a Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Date: Wed, 29 May 2019 09:17:33 +0100
Subject: [PATCH] Fix dropped logcontexts during high outbound traffic. (#5277)
Fixes #5271.
---
changelog.d/5277.bugfix | 1 +
synapse/app/_base.py | 20 +++++++++++++-------
2 files changed, 14 insertions(+), 7 deletions(-)
create mode 100644 changelog.d/5277.bugfix
diff --git a/changelog.d/5277.bugfix b/changelog.d/5277.bugfix
new file mode 100644
index 0000000000..371aa2e7fb
--- /dev/null
+++ b/changelog.d/5277.bugfix
@@ -0,0 +1 @@
+Fix dropped logcontexts during high outbound traffic.
diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index 08199a5e8d..8cc990399f 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -344,15 +344,21 @@ class _LimitedHostnameResolver(object):
def resolveHostName(self, resolutionReceiver, hostName, portNumber=0,
addressTypes=None, transportSemantics='TCP'):
- # Note this is happening deep within the reactor, so we don't need to
- # worry about log contexts.
-
# We need this function to return `resolutionReceiver` so we do all the
# actual logic involving deferreds in a separate function.
- self._resolve(
- resolutionReceiver, hostName, portNumber,
- addressTypes, transportSemantics,
- )
+
+ # even though this is happening within the depths of twisted, we need to drop
+ # our logcontext before starting _resolve, otherwise: (a) _resolve will drop
+ # the logcontext if it returns an incomplete deferred; (b) _resolve will
+ # call the resolutionReceiver *with* a logcontext, which it won't be expecting.
+ with PreserveLoggingContext():
+ self._resolve(
+ resolutionReceiver,
+ hostName,
+ portNumber,
+ addressTypes,
+ transportSemantics,
+ )
return resolutionReceiver
--
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