Ignore AlreadyCalled errors on timer cancel

synapse/push/emailpusher.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 from twisted.internet import defer, reactor
+from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 
 import logging
 
@@ -92,7 +93,11 @@ class EmailPusher(object):
 
     def on_stop(self):
         if self.timed_call:
+            try:
                 self.timed_call.cancel()
+            except (AlreadyCalled, AlreadyCancelled):
+                pass
+            self.timed_call = None
 
     @defer.inlineCallbacks
     def on_new_notifications(self, min_stream_ordering, max_stream_ordering):
@@ -189,7 +194,10 @@ class EmailPusher(object):
                     soonest_due_at = should_notify_at
 
                 if self.timed_call is not None:
+                    try:
                         self.timed_call.cancel()
+                    except (AlreadyCalled, AlreadyCancelled):
+                        pass
                     self.timed_call = None
 
         if soonest_due_at is not None:

synapse/push/httppusher.py

@@ -16,6 +16,7 @@
 from synapse.push import PusherConfigException
 
 from twisted.internet import defer, reactor
+from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 
 import logging
 import push_rule_evaluator
@@ -109,7 +110,11 @@ class HttpPusher(object):
 
     def on_stop(self):
         if self.timed_call:
+            try:
                 self.timed_call.cancel()
+            except (AlreadyCalled, AlreadyCancelled):
+                pass
+            self.timed_call = None
 
     @defer.inlineCallbacks
     def _process(self):