timer_create(3C) Standard C Library Functions timer_create(3C)
NAME
timer_create - create a timer
SYNOPSIS
#include <signal.h>
#include <time.h>
int timer_create(clockid_t clock_id,
struct sigevent *restrict evp, timer_t *restrict timerid);
DESCRIPTION
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 noti-
fication that will occur when the timer expires (see signal.h(3HEAD) for event notification details). 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 the value SIGALARM, and the sigev_value member having the value of the timer ID.
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 sup-
ported:
CLOCK_REALTIME wall clock
CLOCK_VIRTUAL user CPU usage clock
CLOCK_PROF user and system CPU usage clock
CLOCK_HIGHRES non-adjustable, high-resolution clock
For timers created with a clock_id of CLOCK_HIGHRES, the system will attempt to use an optimal hardware source. This may include, but is
not limited to, per-CPU timer sources. The actual hardware source used is transparent to the user and may change over the lifetime of the
timer. For example, if the caller that created the timer were to change its processor binding or its processor set, the system may elect to
drive the timer with a hardware source that better reflects the new binding. Timers based on a clock_id of CLOCK_HIGHRES are ideally
suited for interval timers that have minimal jitter tolerence.
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)).
RETURN VALUES
Upon successful completion, 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.
ERRORS
The timer_create() function will fail if:
EAGAIN 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.
EINVAL The specified clock ID, clock_id, is not defined.
EPERM The specified clock ID, clock_id, is CLOCK_HIGHRES and the {PRIV_PROC_CLOCK_HIGHRES} is not asserted in the effective set of the
calling process.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
|ATTRIBUTE TYPE |ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Committed |
+-----------------------------+-----------------------------+
|MT-Level |MT-Safe with exceptions |
+-----------------------------+-----------------------------+
|Standard |See standards(5). |
+-----------------------------+-----------------------------+
SEE ALSO
exec(2), fork(2), time(2), clock_settime(3C), signal(3C), signal.h(3HEAD), timer_delete(3C), timer_settime(3C), attributes(5), privi-
leges(5), standards(5)
SunOS 5.11 5 Feb 2008 timer_create(3C)