freebsd man page for timer_create

TIMER_CREATE(2) 					      BSD System Calls Manual						   TIMER_CREATE(2)

NAME
     timer_create -- create a per-process timer (REALTIME)

LIBRARY
     POSIX Real-time Library (librt, -lrt)

SYNOPSIS
     #include <time.h>
     #include <signal.h>

     int
     timer_create(clockid_t clockid, struct sigevent *restrict evp, timer_t *restrict timerid);

DESCRIPTION
     The timer_create() system call creates a per-process timer using the specified clock, clock_id, as the timing base.  The timer_create() sys-
     tem call 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 is 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 is 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 to 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.

     The implementations supports a clock_id of CLOCK_REALTIME or CLOCK_MONOTONIC.

     If evp->sigev_notify is SIGEV_THREAD and sev->sigev_notify_attributes is not NULL, if the attribute pointed to by
     sev->sigev_notify_attributes has a thread stack address specified by a call to pthread_attr_setstack() or pthread_attr_setstackaddr(), the
     results are unspecified if the signal is generated more than once.

RETURN VALUES
     If the call succeeds, timer_create() returns zero 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 system call returns a value of -1 and the global variable errno is set to indicate the
     error.  The value of timerid is undefined if an error occurs.

ERRORS
     The timer_create() system call will fail if:

     [EAGAIN]		The calling process has already created all of the timers it is allowed by this implementation.

     [EINVAL]		The specified clock ID is not supported.

     [EFAULT]		Any arguments point outside the allocated address space or there is a memory protection fault.

SEE ALSO
     clock_getres(2), timer_delete(2), timer_getoverrun(2), siginfo(3)

STANDARDS
     The timer_create() system call conforms to IEEE Std 1003.1-2004 (``POSIX.1'').

HISTORY
     Support for POSIX per-process timer first appeared in FreeBSD 7.0.

BSD
								 January 12, 2009							       BSD