        void cancel_deadline_timer()
        {
            CROW_LOG_DEBUG << this << " timer cancelled: " << &task_timer_ << ' ' << task_id_;
            task_timer_.cancel(task_id_);
        }
        void cancel_deadline_timer()
        {
            CROW_LOG_DEBUG << this << " timer cancelled: " << &task_timer_ << ' ' << task_id_;
            task_timer_.cancel(task_id_);
        }