/* * Copyright (c) 2008-2009 Apple Inc. All rights reserved. * * @APPLE_APACHE_LICENSE_HEADER_START@ * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * @APPLE_APACHE_LICENSE_HEADER_END@ */ #ifndef __DISPATCH_ONCE__ #define __DISPATCH_ONCE__ #ifndef __DISPATCH_INDIRECT__ #error "Please #include <dispatch/dispatch.h> instead of this file directly." #include <dispatch/base.h> // for HeaderDoc #endif __BEGIN_DECLS /*! * @typedef dispatch_once_t * * @abstract * A predicate for use with dispatch_once(). It must be initialized to zero. * Note: static and global variables default to zero. */ typedef long dispatch_once_t; /*! * @function dispatch_once * * @abstract * Execute a block once and only once. * * @param predicate * A pointer to a dispatch_once_t that is used to test whether the block has * completed or not. * * @param block * The block to execute once. * * @discussion * Always call dispatch_once() before using or testing any variables that are * initialized by the block. */ #ifdef __BLOCKS__ __OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_NA) DISPATCH_NONNULL_ALL DISPATCH_NOTHROW void dispatch_once(dispatch_once_t *predicate, dispatch_block_t block); #ifdef __GNUC__ #define dispatch_once(x, ...) do { if (__builtin_expect(*(x), ~0l) != ~0l) dispatch_once((x), (__VA_ARGS__)); } while (0) #endif #endif __OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_NA) DISPATCH_NONNULL1 DISPATCH_NONNULL3 DISPATCH_NOTHROW void dispatch_once_f(dispatch_once_t *predicate, void *context, void (*function)(void *)); #ifdef __GNUC__ #define dispatch_once_f(x, y, z) do { if (__builtin_expect(*(x), ~0l) != ~0l) dispatch_once_f((x), (y), (z)); } while (0) #endif __END_DECLS #endif