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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ATOMIC_ATOMIC_SYNC_H
#define _LIBCPP___ATOMIC_ATOMIC_SYNC_H
#include <__atomic/contention_t.h>
#include <__atomic/cxx_atomic_impl.h>
#include <__atomic/memory_order.h>
#include <__availability>
#include <__chrono/duration.h>
#include <__config>
#include <__memory/addressof.h>
#include <__thread/poll_with_backoff.h>
#include <__threading_support>
#include <__type_traits/decay.h>
#include <cstring>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#ifndef _LIBCPP_HAS_NO_THREADS
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __cxx_atomic_notify_one(void const volatile*);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __cxx_atomic_notify_all(void const volatile*);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI __cxx_contention_t __libcpp_atomic_monitor(void const volatile*);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __libcpp_atomic_wait(void const volatile*, __cxx_contention_t);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void
__cxx_atomic_notify_one(__cxx_atomic_contention_t const volatile*);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void
__cxx_atomic_notify_all(__cxx_atomic_contention_t const volatile*);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI __cxx_contention_t
__libcpp_atomic_monitor(__cxx_atomic_contention_t const volatile*);
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void
__libcpp_atomic_wait(__cxx_atomic_contention_t const volatile*, __cxx_contention_t);
template <class _Atp, class _Fn>
struct __libcpp_atomic_wait_backoff_impl {
_Atp* __a;
_Fn __test_fn;
_LIBCPP_AVAILABILITY_SYNC
_LIBCPP_HIDE_FROM_ABI bool operator()(chrono::nanoseconds __elapsed) const {
if (__elapsed > chrono::microseconds(64)) {
auto const __monitor = std::__libcpp_atomic_monitor(__a);
if (__test_fn())
return true;
std::__libcpp_atomic_wait(__a, __monitor);
} else if (__elapsed > chrono::microseconds(4))
__libcpp_thread_yield();
else {
} // poll
return false;
}
};
template <class _Atp, class _Fn>
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool __cxx_atomic_wait(_Atp* __a, _Fn&& __test_fn) {
__libcpp_atomic_wait_backoff_impl<_Atp, __decay_t<_Fn> > __backoff_fn = {__a, __test_fn};
return std::__libcpp_thread_poll_with_backoff(__test_fn, __backoff_fn);
}
#else // _LIBCPP_HAS_NO_THREADS
template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void __cxx_atomic_notify_all(__cxx_atomic_impl<_Tp> const volatile*) {}
template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void __cxx_atomic_notify_one(__cxx_atomic_impl<_Tp> const volatile*) {}
template <class _Atp, class _Fn>
_LIBCPP_HIDE_FROM_ABI bool __cxx_atomic_wait(_Atp*, _Fn&& __test_fn) {
return std::__libcpp_thread_poll_with_backoff(__test_fn, __spinning_backoff_policy());
}
#endif // _LIBCPP_HAS_NO_THREADS
template <typename _Tp>
_LIBCPP_HIDE_FROM_ABI bool __cxx_nonatomic_compare_equal(_Tp const& __lhs, _Tp const& __rhs) {
return std::memcmp(std::addressof(__lhs), std::addressof(__rhs), sizeof(_Tp)) == 0;
}
template <class _Atp, class _Tp>
struct __cxx_atomic_wait_test_fn_impl {
_Atp* __a;
_Tp __val;
memory_order __order;
_LIBCPP_HIDE_FROM_ABI bool operator()() const {
return !std::__cxx_nonatomic_compare_equal(std::__cxx_atomic_load(__a, __order), __val);
}
};
template <class _Atp, class _Tp>
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI bool
__cxx_atomic_wait(_Atp* __a, _Tp const __val, memory_order __order) {
__cxx_atomic_wait_test_fn_impl<_Atp, _Tp> __test_fn = {__a, __val, __order};
return std::__cxx_atomic_wait(__a, __test_fn);
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ATOMIC_ATOMIC_SYNC_H
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