Invoked once the request has been finished. Increment a counter
        created in the format:

            package[.module].Class.METHOD.STATUS
            tornado.web.RequestHandler.GET.200

def on_finish(self):
        """Invoked once the request has been finished. Increment a counter
        created in the format:

            package[.module].Class.METHOD.STATUS
            tornado.web.RequestHandler.GET.200

        """
        super(StatsdMixin, self).on_finish()
        key = '%s.%s.%s.%s' % (self.__module__,
                               self.__class__.__name__,
                               self.request.method, self._status_code)
        LOGGER.info('Processing %s', key)
        self.statsd_incr(key)
        self.statsd_add_timing(key, self.request.request_time() * 1000)