Sun Microsystems, Inc. gratefully acknowledges The Open Group for
permission to reproduce portions of its copyrighted documentation.
Original documentation from The Open Group can be obtained online at
http://www.opengroup.org/bookstore/.

The Institute of Electrical and Electronics Engineers and The Open
Group, have given us permission to reprint portions of their
documentation.

In the following statement, the phrase ``this text'' refers to portions
of the system documentation.

Portions of this text are reprinted and reproduced in electronic form
in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6,
Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy
between these versions and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html.

This notice shall appear on any product containing this material.

The contents of this file are subject to the terms of the
Common Development and Distribution License (the "License").
You may not use this file except in compliance with the License.

You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
or http://www.opensolaris.org/os/licensing.
See the License for the specific language governing permissions
and limitations under the License.

When distributing Covered Code, include this CDDL HEADER in each
file and include the License file at usr/src/OPENSOLARIS.LICENSE.
If applicable, add the following below this CDDL HEADER, with the
fields enclosed by brackets "[]" replaced with your own identifying
information: Portions Copyright [yyyy] [name of copyright owner]


Copyright 1989 AT&T
Portions Copyright (c) 1992, X/Open Company Limited. All Rights Reserved.
Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved.

timer_create - create a timer

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

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

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(), and can be started using timer_settime(3C).

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 (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 SIGALRM, 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 supported: CLOCK_REALTIME

CLOCK_HIGHRES

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 tolerance.

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)).

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. The timer_create() function will fail if: EAGAIN EINVAL See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE

Interface Stability Committed

MT-Level MT-Safe with exceptions

Standard See standards(7).

exec (2), fork (2), time (2), clock_settime (3C), signal (3C), timer_delete (3C), timer_settime (3C), signal.h (3HEAD), attributes (7), standards (7)