1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #ifndef _LIBCPP___MUTEX_ONCE_FLAG_H
10 #define _LIBCPP___MUTEX_ONCE_FLAG_H
11
12 #include <__config>
13 #include <__functional/invoke.h>
14 #include <__memory/shared_ptr.h> // __libcpp_acquire_load
15 #include <__tuple/tuple_indices.h>
16 #include <__tuple/tuple_size.h>
17 #include <__utility/forward.h>
18 #include <__utility/move.h>
19 #include <cstdint>
20 #ifndef _LIBCPP_CXX03_LANG
21 # include <tuple>
22 #endif
23
24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
25 # pragma GCC system_header
26 #endif
27
28 _LIBCPP_PUSH_MACROS
29 #include <__undef_macros>
30
31 _LIBCPP_BEGIN_NAMESPACE_STD
32
33 struct _LIBCPP_TEMPLATE_VIS once_flag;
34
35 #ifndef _LIBCPP_CXX03_LANG
36
37 template <class _Callable, class... _Args>
38 _LIBCPP_HIDE_FROM_ABI void call_once(once_flag&, _Callable&&, _Args&&...);
39
40 #else // _LIBCPP_CXX03_LANG
41
42 template <class _Callable>
43 _LIBCPP_HIDE_FROM_ABI void call_once(once_flag&, _Callable&);
44
45 template <class _Callable>
46 _LIBCPP_HIDE_FROM_ABI void call_once(once_flag&, const _Callable&);
47
48 #endif // _LIBCPP_CXX03_LANG
49
50 struct _LIBCPP_TEMPLATE_VIS once_flag {
once_flagonce_flag51 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR once_flag() _NOEXCEPT : __state_(_Unset) {}
52 once_flag(const once_flag&) = delete;
53 once_flag& operator=(const once_flag&) = delete;
54
55 #if defined(_LIBCPP_ABI_MICROSOFT)
56 typedef uintptr_t _State_type;
57 #else
58 typedef unsigned long _State_type;
59 #endif
60
61 static const _State_type _Unset = 0;
62 static const _State_type _Pending = 1;
63 static const _State_type _Complete = ~_State_type(0);
64
65 private:
66 _State_type __state_;
67
68 #ifndef _LIBCPP_CXX03_LANG
69 template <class _Callable, class... _Args>
70 friend void call_once(once_flag&, _Callable&&, _Args&&...);
71 #else // _LIBCPP_CXX03_LANG
72 template <class _Callable>
73 friend void call_once(once_flag&, _Callable&);
74
75 template <class _Callable>
76 friend void call_once(once_flag&, const _Callable&);
77 #endif // _LIBCPP_CXX03_LANG
78 };
79
80 #ifndef _LIBCPP_CXX03_LANG
81
82 template <class _Fp>
83 class __call_once_param {
84 _Fp& __f_;
85
86 public:
__call_once_param(_Fp & __f)87 _LIBCPP_HIDE_FROM_ABI explicit __call_once_param(_Fp& __f) : __f_(__f) {}
88
operator()89 _LIBCPP_HIDE_FROM_ABI void operator()() {
90 typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 1>::type _Index;
91 __execute(_Index());
92 }
93
94 private:
95 template <size_t... _Indices>
__execute(__tuple_indices<_Indices...>)96 _LIBCPP_HIDE_FROM_ABI void __execute(__tuple_indices<_Indices...>) {
97 std::__invoke(std::get<0>(std::move(__f_)), std::get<_Indices>(std::move(__f_))...);
98 }
99 };
100
101 #else
102
103 template <class _Fp>
104 class __call_once_param {
105 _Fp& __f_;
106
107 public:
__call_once_param(_Fp & __f)108 _LIBCPP_HIDE_FROM_ABI explicit __call_once_param(_Fp& __f) : __f_(__f) {}
109
operator()110 _LIBCPP_HIDE_FROM_ABI void operator()() { __f_(); }
111 };
112
113 #endif
114
115 template <class _Fp>
__call_once_proxy(void * __vp)116 void _LIBCPP_HIDE_FROM_ABI __call_once_proxy(void* __vp) {
117 __call_once_param<_Fp>* __p = static_cast<__call_once_param<_Fp>*>(__vp);
118 (*__p)();
119 }
120
121 _LIBCPP_EXPORTED_FROM_ABI void __call_once(volatile once_flag::_State_type&, void*, void (*)(void*));
122
123 #ifndef _LIBCPP_CXX03_LANG
124
125 template <class _Callable, class... _Args>
call_once(once_flag & __flag,_Callable && __func,_Args &&...__args)126 inline _LIBCPP_HIDE_FROM_ABI void call_once(once_flag& __flag, _Callable&& __func, _Args&&... __args) {
127 if (__libcpp_acquire_load(&__flag.__state_) != once_flag::_Complete) {
128 typedef tuple<_Callable&&, _Args&&...> _Gp;
129 _Gp __f(std::forward<_Callable>(__func), std::forward<_Args>(__args)...);
130 __call_once_param<_Gp> __p(__f);
131 std::__call_once(__flag.__state_, &__p, &__call_once_proxy<_Gp>);
132 }
133 }
134
135 #else // _LIBCPP_CXX03_LANG
136
137 template <class _Callable>
call_once(once_flag & __flag,_Callable & __func)138 inline _LIBCPP_HIDE_FROM_ABI void call_once(once_flag& __flag, _Callable& __func) {
139 if (__libcpp_acquire_load(&__flag.__state_) != once_flag::_Complete) {
140 __call_once_param<_Callable> __p(__func);
141 std::__call_once(__flag.__state_, &__p, &__call_once_proxy<_Callable>);
142 }
143 }
144
145 template <class _Callable>
call_once(once_flag & __flag,const _Callable & __func)146 inline _LIBCPP_HIDE_FROM_ABI void call_once(once_flag& __flag, const _Callable& __func) {
147 if (__libcpp_acquire_load(&__flag.__state_) != once_flag::_Complete) {
148 __call_once_param<const _Callable> __p(__func);
149 std::__call_once(__flag.__state_, &__p, &__call_once_proxy<const _Callable>);
150 }
151 }
152
153 #endif // _LIBCPP_CXX03_LANG
154
155 _LIBCPP_END_NAMESPACE_STD
156
157 _LIBCPP_POP_MACROS
158
159 #endif // _LIBCPP___MUTEX_ONCE_FLAG_H
160