Use deferred.addTimeout instead of time_bound_deferred

This doesn't feel like a wheel we need to reinvent.

synapse/http/client.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2018 New Vector Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -18,9 +19,9 @@ from OpenSSL.SSL import VERIFY_NONE
 from synapse.api.errors import (
     CodeMessageException, MatrixCodeMessageException, SynapseError, Codes,
 )
+from synapse.http import cancelled_to_request_timed_out_error
 from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.logcontext import make_deferred_yieldable
-from synapse.util import logcontext
 import synapse.metrics
 from synapse.http.endpoint import SpiderEndpoint
 
@@ -95,21 +96,16 @@ class SimpleHttpClient(object):
         # counters to it
         outgoing_requests_counter.inc(method)
 
-        def send_request():
-            request_deferred = self.agent.request(
-                method, uri, *args, **kwargs
-            )
-
-            return self.clock.time_bound_deferred(
-                request_deferred,
-                time_out=60,
-            )
-
         logger.info("Sending request %s %s", method, uri)
 
         try:
-            with logcontext.PreserveLoggingContext():
-                response = yield send_request()
+            request_deferred = self.agent.request(
+                method, uri, *args, **kwargs
+            )
+            request_deferred.addTimeout(
+                60, reactor, cancelled_to_request_timed_out_error,
+            )
+            response = yield make_deferred_yieldable(request_deferred)
 
             incoming_responses_counter.inc(method, response.code)
             logger.info(