timer_create(3)timer_create(3)NAMEtimer_create - Allocates a per-process timer
SYNOPSIS
#include <signal.h> #include <time.h>
int timer_create ( clockid_t clock_id, struct sigevent *evp,
timer_t *timerid );
LIBRARY
Realtime Library (librt.so, librt.a)
PARAMETERS
The type of clock on which the timer is based. The CLOCK_REALTIME clock
is supported. A pointer to a sigevent structure, which defines the
signal sent to the process on timer expiration. A pointer to the timer
ID returned by the call to the timer_create function.
DESCRIPTION
The timer_create function allocates a per-process timer using the spec‐
ified clock as the timing base. The timer_create function returns
timer_id, which identifies the timer in timer requests. The timer ID is
unique within the calling process until the timer is deleted. The timer
is unarmed when first returned from a call to timer_create. To arm the
timer, use the timer_settime function.
The evp argument, if non-NULL, points to a sigevent structure, which
defines the asynchronous notification that occurs when the timer
expires. If the sigev_notify member of evp is SIGEV_SIGNAL, the struc‐
ture must contain the signal number and data value to send to the
process when the timer expires.
SIGALRM is the default signal for CLOCK_REALTIME if the evp argument is
NULL.
The maximum number of timers supported per process (TIMER_MAX) is
defined in the <sys/rt_limits.h> header file, which is indirectly
included through <time.h>.
Timers are not inherited across fork calls. An exec call disarms and
deletes a timer.
RETURN VALUES
Upon successful completion, a value of 0 (zero) is returned. The
timer_create function also returns, in timerid, a pointer to the timer
ID that has been created.
An unsuccessful call returns -1, and errno is set to indicate the error
type.
ERRORS
The timer_create function fails under the following conditions: The
system lacks sufficient signal queuing resources to honor the request.
The calling process has already created all of the timers it is
allowed. The specified clock ID is not defined.
SEE ALSO
Functions: clock_getres(3), clock_gettime(3), clock_settime(3),
timer_delete(3), timer_gettime(3), timer_settime(3)
Guide to Realtime Programming
timer_create(3)
