Updated: April 19, 2023 |
Set the value of an interval timer
#include <sys/time.h> int setitimer ( int which, const struct itimerval *value, struct itimerval *ovalue );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The setitimer() function sets the value of the timer specified by which to the value specified in the structure pointed to by value, and if ovalue isn't NULL, stores the previous value of the timer in the structure it points to.
The setitimer() function is independent of alarm().
A timer value is defined by the itimerval structure, which includes the following members:
struct timeval it_interval; /* timer interval */ struct timeval it_value; /* current value */
Each struct timeval contains the following members:
The it_value member indicates the time to the next timer expiration. The it_interval member specifies a value to be used in reloading it_value when the timer expires. Setting it_value to 0 disables a timer, regardless of the value of it_interval. Setting it_interval to 0 disables a timer after its next expiration (assuming it_value is nonzero).
Time values smaller than the resolution of the system clock are rounded up to the resolution of the system clock.
The only supported timer is ITIMER_REAL, which decrements in real time. A SIGALRM signal is delivered when this timer expires.
POSIX 1003.1 OB XSI. This function is marked as obsolescent, and may be removed from a future version of the standard.
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | Yes |
Thread | Yes |