Manual page for timer_create(3R)
timer_create - create a timer
SYNOPSIS
cc
[ flag ... ] file ...
-lposix4
[ library ... ]
#include <signal.h>
#include <time.h>
int timer_create(clockid_t clock_id, struct sigevent *evp,
timer_t *timerid);
struct sigevent {
int sigev_notify /* notification type */
int sigev_signo; /* signal number */
union sigval sigev_value; /* signal value */
};
union sigval {
int sival_int; /* integer value */
void *sival_ptr; /* pointer value */
};
MT-LEVEL
MT-Safe with exceptions
DESCRIPTION
timer_create()
creates a timer using the specified clock,
clock_id,
as the timing base.
This timer ID is unique and meaningful only within the calling LWP
until the timer is deleted.
This timer is initially disarmed upon return from
timer_create().
The timer may be created per-LWP or per-process.
Expiration signals for a per-LWP timer will be sent to the creating LWP.
Expiration signals for a per-process timer will be sent to the process.
A per-LWP timer will be automatically deleted when the creating LWP exits.
By default, timers are created per-LWP.
If the symbol
_POSIX_PER_PROCESS_TIMERS
is defined
or the symbol
_POSIX_C_SOURCE
is defined to have a value greater than
199500L
before the inclusion of
<time.h>,
timers will be created per-process.
If
evp
is non-NULL:
-
then
evp
points to a
sigevent
structure, allocated by the application, which
defines the asynchronous notification that will occur when the timer expires.
If the
sigev_notify
member of
evp
is
SIGEV_SIGNAL,
then the structure also contains the signal number
and the application specific data value to be sent to the process.
If
SA_SIGINFO
is set for the expiration
signal, then the signal and application-defined value specified in
the structure will be queued to the process on timer expiration.
If
SA_SIGINFO
is not set for the expiration signal,
then the signal specified in the structure will be sent
upon the timer expiration.
If the
sigev_notify
member is
SIGEV_NONE,
no notification will be sent.
If
evp
is
NULL,
and
SA_SIGINFO
is set for the expiration signal,
then the default signal,
SIGALRM,
will be queued to the process
and the signal data value will be set to the timer ID.
RETURN VALUES
timer_create()
returns
0
upon success and creates a
timer_t,
timerid,
which can be passed to the timer calls;
otherwise it returns
-1
and sets
errno
to indicate the error condition.
ERRORS
- EAGAIN
-
The system lacks sufficient signal queuing resources to honor the request.
The calling process has already created
all of the timers it is allowed by this implementation.
- EINVAL
-
The specified clock ID,
clock_id,
is not defined.
- ENOSYS
-
timer_create()
is not supported by this implementation.
SEE ALSO
exec.2
fork.2
time.2
clock_settime.3r
timer_delete.3r
timer_settime.3r
NOTES
Timers are not inherited by a child process across a
fork.2
and can be disarmed and deleted by an
exec.2
In a future release,
the ability to create per-LWP timers will be removed,
and all calls to
timer_create()
will result in per-process timers.
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97
