struct timer {
    struct timeval begin;
    struct timeval end;
    int (*expired)(struct timer *timer);
};

struct timer *new_timer(time_t sec, suseconds_t usec);

int delay(int64_t ns);

double timeval_to_double(struct timeval *tv);

double timeval_diff(struct timeval *tv0, struct timeval *tv1);

void update_timer(struct timer *tp, time_t sec, suseconds_t usec);

int64_t timer_remaining(struct timer *tp);

void free_timer(struct timer *tp);