1/* $NetBSD: once.h,v 1.5 2008/10/09 10:48:21 pooka Exp $ */
2
3/*-
4 * Copyright (c)2005 YAMAMOTO Takashi,
5 * Copyright (c)2008 Antti Kantee,
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#ifndef _SYS_ONCE_H_
31#define _SYS_ONCE_H_
32
33typedef struct {
34 unsigned o_status;
35 int o_error;
36#define ONCE_VIRGIN 0
37#define ONCE_RUNNING 1
38#define ONCE_DONE 2
39} once_t;
40
41void once_init(void);
42int _run_once(once_t *, int (*)(void));
43
44#define ONCE_DECL(o) \
45 once_t (o) = { \
46 .o_status = 0, \
47 };
48
49#define RUN_ONCE(o, fn) \
50 (__predict_true((o)->o_status == ONCE_DONE) ? \
51 ((o)->o_error) : _run_once((o), (fn)))
52
53#endif /* _SYS_ONCE_H_ */
54