int event_base_once (struct event_base *base, int fd, short events, void (*cb)(int, short, void *), void *arg, struct timeval *tv);
int event_base_priority_init (struct event_base *base, int fd);
int event_base_once (struct event_base *base, int fd, short events, void (*cb)(int, short, void *), void *arg, struct timeval *tv);
int event_base_priority_init (struct event_base *base, int fd);