/*
 * Copyright (c) 2008-2024 Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This file is part of ObjFW. It may be distributed under the terms of the
 * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
 * the packaging of this file.
 *
 * Alternatively, it may be distributed under the terms of the GNU General
 * Public License, either version 2 or 3, which can be found in the file
 * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
 * file.
 */

#include "objfw-defs.h"

#import "macros.h"

#if defined(OF_HAVE_PTHREADS)
# include <pthread.h>
typedef pthread_once_t OFOnceControl;
# define OFOnceControlInitValue PTHREAD_ONCE_INIT
#elif defined(OF_HAVE_ATOMIC_OPS)
typedef volatile int OFOnceControl;
# define OFOnceControlInitValue 0
#elif defined(OF_AMIGAOS) || !defined(OF_HAVE_THREADS)
typedef int OFOnceControl;
# define OFOnceControlInitValue 0
#endif

OF_ASSUME_NONNULL_BEGIN

/** @file */

typedef void (*OFOnceFunction)(void);

#ifdef __cplusplus
extern "C" {
#endif
/**
 * @brief Executes the specified function exactly once in the application's
 *	  lifetime, even in a multi-threaded environment.
 *
 * @param control An OFOnceControl. This should be a static variable
 *		  preinitialized to `OFOnceControlInitValue`.
 * @param function The function to execute once
 */
extern void OFOnce(OFOnceControl *control, OFOnceFunction function);
#ifdef __cplusplus
}
#endif

OF_ASSUME_NONNULL_END