Specifies the number of seconds of the initial expiration of the timer.
Specifies an amount of milliseconds that will be added to first_s.
Specifies the number of seconds of the period for repeated timer expirations after the initial expiration.
Specifies an amount of milliseconds that will be added to interval_ms.
the previous expiration time as time().
upon failure to set the time
Sets next expiration time of interval timer.
Setting first_s or first_ms to a non-zero value arms the timer. Setting both to zero disarms the timer. If both interval_s and interval_ms are zero, the timer expires just once, at the time specified by first_s and first_ms.