void backend_add_timeout(struct io_conn *conn, struct timespec ts);
void backend_del_timeout(struct io_conn *conn);
void backend_del_conn(struct io_conn *conn);
void backend_add_timeout(struct io_conn *conn, struct timespec ts);
void backend_del_timeout(struct io_conn *conn);
void backend_del_conn(struct io_conn *conn);