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 33 typedef 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 41 void once_init(void); 42 int _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