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/*
* Copyright (c) 2008-2010 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
DISPATCH_ASSUME_NONNULL_BEGIN
__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.
*/
DISPATCH_SWIFT3_UNAVAILABLE("Use lazily initialized globals instead")
typedef intptr_t dispatch_once_t;
#if defined(__x86_64__) || defined(__i386__) || defined(__s390x__)
#define DISPATCH_ONCE_INLINE_FASTPATH 1
#elif defined(__APPLE__)
#define DISPATCH_ONCE_INLINE_FASTPATH 1
#else
#define DISPATCH_ONCE_INLINE_FASTPATH 0
#endif
/*!
* @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__
API_AVAILABLE(macos(10.6), ios(4.0))
DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
DISPATCH_SWIFT3_UNAVAILABLE("Use lazily initialized globals instead")
void
dispatch_once(dispatch_once_t *predicate,
DISPATCH_NOESCAPE dispatch_block_t block);
#if DISPATCH_ONCE_INLINE_FASTPATH
DISPATCH_INLINE DISPATCH_ALWAYS_INLINE DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
DISPATCH_SWIFT3_UNAVAILABLE("Use lazily initialized globals instead")
void
_dispatch_once(dispatch_once_t *predicate,
DISPATCH_NOESCAPE dispatch_block_t block)
{
if (DISPATCH_EXPECT(*predicate, ~0l) != ~0l) {
dispatch_once(predicate, block);
} else {
dispatch_compiler_barrier();
}
DISPATCH_COMPILER_CAN_ASSUME(*predicate == ~0l);
}
#undef dispatch_once
#define dispatch_once _dispatch_once
#endif
#endif // DISPATCH_ONCE_INLINE_FASTPATH
API_AVAILABLE(macos(10.6), ios(4.0))
DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_NONNULL3 DISPATCH_NOTHROW
DISPATCH_SWIFT3_UNAVAILABLE("Use lazily initialized globals instead")
void
dispatch_once_f(dispatch_once_t *predicate, void *_Nullable context,
dispatch_function_t function);
#if DISPATCH_ONCE_INLINE_FASTPATH
DISPATCH_INLINE DISPATCH_ALWAYS_INLINE DISPATCH_NONNULL1 DISPATCH_NONNULL3
DISPATCH_NOTHROW
DISPATCH_SWIFT3_UNAVAILABLE("Use lazily initialized globals instead")
void
_dispatch_once_f(dispatch_once_t *predicate, void *_Nullable context,
dispatch_function_t function)
{
if (DISPATCH_EXPECT(*predicate, ~0l) != ~0l) {
dispatch_once_f(predicate, context, function);
} else {
dispatch_compiler_barrier();
}
DISPATCH_COMPILER_CAN_ASSUME(*predicate == ~0l);
}
#undef dispatch_once_f
#define dispatch_once_f _dispatch_once_f
#endif // DISPATCH_ONCE_INLINE_FASTPATH
__END_DECLS
DISPATCH_ASSUME_NONNULL_END
#endif
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