once.c   [plain text]

/*
 * Copyright (C) 2004, 2007  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id: once.c,v 1.12 2007/06/18 23:47:49 tbox Exp $ */

/* Principal Authors: DCL */

#include <config.h>

#include <windows.h>

#include <isc/once.h>
#include <isc/assertions.h>
#include <isc/util.h>

isc_result_t
isc_once_do(isc_once_t *controller, void(*function)(void)) {
	REQUIRE(controller != NULL && function != NULL);

	if (controller->status == ISC_ONCE_INIT_NEEDED) {

		if (InterlockedDecrement(&controller->counter) == 0) {
			if (controller->status == ISC_ONCE_INIT_NEEDED) {
				function();
				controller->status = ISC_ONCE_INIT_DONE;
			}
		} else {
			while (controller->status == ISC_ONCE_INIT_NEEDED) {
				/*
				 * Sleep(0) indicates that this thread 
				 * should be suspended to allow other 
				 * waiting threads to execute.
				 */
				Sleep(0);
			}
		}
	}

	return (ISC_R_SUCCESS);
}