NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | ATTRIBUTES | SEE ALSO | NOTES
cc [ flag... ] file... -lrt [ library... ] #include <signal.h> #include <time.h>int timer_create(clockid_t clock_id, struct sigevent *evp, timer_t *timerid);
The timer_create() function creates a timer using the specified clock, clock_id, as the timing base. The timer_create() function returns, in the location referenced by timerid, a timer ID of type timer_t used to identify the timer in timer requests. This timer ID will be unique within the calling process until the timer is deleted. The particular clock, clock_id, is defined in <time.h>. The timer whose ID is returned will be in a disarmed state upon return from timer_create().
The evp argument, if non-NULL, points to a sigevent structure. This structure, allocated by the application, defines the asynchronous notification that willo occur when the timer expires. If the evp argument is NULL, the effect is as if the evp argument pointed to a sigevent structure with the sigev_notify member having the value SIGEV_SIGNAL, the sigev_signo having a default signal number, and the sigev_value member having the value of the timer ID, timerid.
The system defines a set of clocks that can be used as timing bases for per-process timers. The following values for clock_id are supported:
wall clock, not bound
user CPU usage clock
user and system CPU usage clock
Timers are not inherited by a child process across a fork(2) and are disarmed and deleted by a call to one of the exec functions (see exec(2)).
If the call succeeds, timer_create() returns 0 and updates the location referenced by timerid to a timer_t, which can be passed to the per-process timer calls. If an error occurs, the function returns -1 and sets errno to indicate the error. The value of timerid is undefined if an error occurs.
The timer_create() function will fail if:
The system lacks sufficient signal queuing resources to honor the request, or the calling process has already created all of the timers it is allowed by the system.
The specified clock ID, clock_id, is not defined.
The timer_create() function is not supported by the system.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE | ATTRIBUTE VALUE |
MT-Level | MT-Safe with exceptions |
exec(2), fork(2), time(2), clock_settime(3R), signal(3C), timer_delete(3R), timer_settime(3R), attributes(5)
Due to the way that signals are handled, if two timers expire at approximately the same time, the signal handler might not detect both of them.
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | ATTRIBUTES | SEE ALSO | NOTES