Fix notification for NotImplemented record_events

With mongodb as storage backend, notification-to-sample will be broken by
NotImplementedError of record_events() method if we have set
"store_events" option as True in ceilometer.conf.

This patch catch the NotImplementedError and enable the
notification-to-sample process.

Change-Id: I7ace5a8581518fa56e58abca2e377b513ff38675
Closes-Bug: #1320420

ceilometer/event/endpoint.py

@@ -64,7 +64,12 @@ class EventsNotificationEndpoint(object):
             LOG.debug(_('Saving event "%s"'), event.event_type)
             problem_events = []
             for dispatcher_ext in self.dispatcher_manager:
-                problem_events.extend(dispatcher_ext.obj.record_events(event))
+                try:
+                    problem_events.extend(
+                        dispatcher_ext.obj.record_events(event))
+                except NotImplementedError:
+                    LOG.warn(_('Event is not implemented with the storage'
+                               ' backend'))
             if models.Event.UNKNOWN_PROBLEM in [x[0] for x in problem_events]:
                 if not cfg.CONF.notification.ack_on_event_error:
                     return oslo.messaging.NotificationResult.REQUEUE

ceilometer/tests/event/test_endpoint.py

@@ -101,6 +101,15 @@ class TestEventEndpoint(tests_base.BaseTestCase):
         self.endpoint.event_converter.to_event.return_value = mock.MagicMock(
             event_type='test.test')
 
+    @mock.patch('ceilometer.event.endpoint.LOG')
+    def test_event_not_implemented(self, log):
+        self.mock_dispatcher.record_events.side_effect = NotImplementedError
+        message = {'event_type': "foo", 'message_id': "abc"}
+        ret = self.endpoint.process_notification(message)
+        log.warn.assert_called_once_with(
+            'Event is not implemented with the storage backend')
+        self.assertEqual(oslo.messaging.NotificationResult.HANDLED, ret)
+
     def test_message_to_event(self):
         self.endpoint.info(TEST_NOTICE_CTXT, 'compute.vagrant-precise',
                            'compute.instance.create.end',