once.c revision 290001 
1/*
2 * Copyright (C) 2004, 2007  Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1999-2001  Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/* $Id: once.c,v 1.12 2007/06/18 23:47:49 tbox Exp $ */
19
20/* Principal Authors: DCL */
21
22#include <config.h>
23
24#include <windows.h>
25
26#include <isc/once.h>
27#include <isc/assertions.h>
28#include <isc/util.h>
29
30isc_result_t
31isc_once_do(isc_once_t *controller, void(*function)(void)) {
32	REQUIRE(controller != NULL && function != NULL);
33
34	if (controller->status == ISC_ONCE_INIT_NEEDED) {
35
36		if (InterlockedDecrement(&controller->counter) == 0) {
37			if (controller->status == ISC_ONCE_INIT_NEEDED) {
38				function();
39				controller->status = ISC_ONCE_INIT_DONE;
40			}
41		} else {
42			while (controller->status == ISC_ONCE_INIT_NEEDED) {
43				/*
44				 * Sleep(0) indicates that this thread
45				 * should be suspended to allow other
46				 * waiting threads to execute.
47				 */
48				Sleep(0);
49			}
50		}
51	}
52
53	return (ISC_R_SUCCESS);
54}
55