timer_create(S)
timer_create --
create a per-process timer
Syntax
cc . . . -lsuds
#include <signal.h>
#include <time.h>
int timer_create(clockid_t clock_id, struct sigevent *evp,
timer_t *timerid);
Description
The timer_create function creates a per-process 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 (see
timer_settime(S)).
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 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 when the timer expires. If the
sigev_notify member is SIGEV_NONE, no
notification is sent.
A set of clocks is defined; these can be used as timing bases for
per-process timers, and one or more mechanisms for notifying the
process of timer expiration events. A clock ID of
CLOCK_REALTIME and signals are supported (see Section 3.3
of IEEE Std 1003.1b-1993 for more details).
If evp points to a sigevent structure that
specifies SIGEV_SIGNAL, then the signal number defined in
the sigevent structure is sent to the process on timer
expiration. If evp is NULL, then a default
signal is sent to the process.
If clock_id specifies the CLOCK_REALTIME system
clock, then the default signal, when evp is NULL,
is SIGALRM.
Per-process timers are not inherited by a child process across a
fork(S)
and are disarmed and deleted by an
exec(S).
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
(see Section 14.2.4 of IEEE Std 1003.1b-1993).
If an error occurs, the function returns a value of -l and sets
errno to indicate the error.
Diagnostics
If any of the following conditions occur, the timer_create
function returns -1 and sets errno to the corresponding
value:
[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.
[EINVAL]-
The specified clock ID is not defined.
See also
time(FP),
timer_delete(S),
timer_gettime(S),
timer_settime(S)
Standards conformance
Text reprinted and/or adapted from IEEE Std 1003.1b-1993,
IEEE Standard for Information Technology, POSIX
Part 1: System Application Program Interface (API)
Amendment 1: Realtime Extensions [C Language], copyright © 1993
by the Institute of Electrical and Electronics Engineers, Inc. The
IEEE takes no responsibility for and will assume no
liability for damages resulting from the reader's misinterpretation
of said information resulting from the placement and context in this
publication. Information is reproduced with the permission of the
IEEE.
© 2003 Caldera International, Inc. All rights reserved.
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