| //===----------------------------------------------------------------------===// |
| // |
| // 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 |