1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___THREAD_JTHREAD_H
11#define _LIBCPP___THREAD_JTHREAD_H
12
13#include <__config>
14#include <__functional/invoke.h>
15#include <__stop_token/stop_source.h>
16#include <__stop_token/stop_token.h>
17#include <__thread/support.h>
18#include <__thread/thread.h>
19#include <__type_traits/decay.h>
20#include <__type_traits/is_constructible.h>
21#include <__type_traits/is_same.h>
22#include <__type_traits/remove_cvref.h>
23#include <__utility/forward.h>
24#include <__utility/move.h>
25
26#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27# pragma GCC system_header
28#endif
29
30_LIBCPP_PUSH_MACROS
31#include <__undef_macros>
32
33#if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
34
35_LIBCPP_BEGIN_NAMESPACE_STD
36
37class _LIBCPP_AVAILABILITY_SYNC jthread {
38public:
39 // types
40 using id = thread::id;
41 using native_handle_type = thread::native_handle_type;
42
43 // [thread.jthread.cons], constructors, move, and assignment
44 _LIBCPP_HIDE_FROM_ABI jthread() noexcept : __stop_source_(std::nostopstate) {}
45
46 template <class _Fun, class... _Args>
47 _LIBCPP_HIDE_FROM_ABI explicit jthread(_Fun&& __fun, _Args&&... __args)
48 requires(!std::is_same_v<remove_cvref_t<_Fun>, jthread>)
49 : __stop_source_(),
50 __thread_(__init_thread(__stop_source_, std::forward<_Fun>(__fun), std::forward<_Args>(__args)...)) {
51 static_assert(is_constructible_v<decay_t<_Fun>, _Fun>);
52 static_assert((is_constructible_v<decay_t<_Args>, _Args> && ...));
53 static_assert(is_invocable_v<decay_t<_Fun>, decay_t<_Args>...> ||
54 is_invocable_v<decay_t<_Fun>, stop_token, decay_t<_Args>...>);
55 }
56
57 _LIBCPP_HIDE_FROM_ABI ~jthread() {
58 if (joinable()) {
59 request_stop();
60 join();
61 }
62 }
63
64 jthread(const jthread&) = delete;
65
66 _LIBCPP_HIDE_FROM_ABI jthread(jthread&&) noexcept = default;
67
68 jthread& operator=(const jthread&) = delete;
69
70 _LIBCPP_HIDE_FROM_ABI jthread& operator=(jthread&& __other) noexcept {
71 if (this != &__other) {
72 if (joinable()) {
73 request_stop();
74 join();
75 }
76 __stop_source_ = std::move(__other.__stop_source_);
77 __thread_ = std::move(__other.__thread_);
78 }
79
80 return *this;
81 }
82
83 // [thread.jthread.mem], members
84 _LIBCPP_HIDE_FROM_ABI void swap(jthread& __other) noexcept {
85 std::swap(__stop_source_, __other.__stop_source_);
86 std::swap(__thread_, __other.__thread_);
87 }
88
89 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool joinable() const noexcept { return get_id() != id(); }
90
91 _LIBCPP_HIDE_FROM_ABI void join() { __thread_.join(); }
92
93 _LIBCPP_HIDE_FROM_ABI void detach() { __thread_.detach(); }
94
95 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI id get_id() const noexcept { return __thread_.get_id(); }
96
97 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return __thread_.native_handle(); }
98
99 // [thread.jthread.stop], stop token handling
100 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI stop_source get_stop_source() noexcept { return __stop_source_; }
101
102 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI stop_token get_stop_token() const noexcept { return __stop_source_.get_token(); }
103
104 _LIBCPP_HIDE_FROM_ABI bool request_stop() noexcept { return __stop_source_.request_stop(); }
105
106 // [thread.jthread.special], specialized algorithms
107 _LIBCPP_HIDE_FROM_ABI friend void swap(jthread& __lhs, jthread& __rhs) noexcept { __lhs.swap(__rhs); }
108
109 // [thread.jthread.static], static members
110 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static unsigned int hardware_concurrency() noexcept {
111 return thread::hardware_concurrency();
112 }
113
114private:
115 template <class _Fun, class... _Args>
116 _LIBCPP_HIDE_FROM_ABI static thread __init_thread(const stop_source& __ss, _Fun&& __fun, _Args&&... __args) {
117 if constexpr (is_invocable_v<decay_t<_Fun>, stop_token, decay_t<_Args>...>) {
118 return thread(std::forward<_Fun>(__fun), __ss.get_token(), std::forward<_Args>(__args)...);
119 } else {
120 return thread(std::forward<_Fun>(__fun), std::forward<_Args>(__args)...);
121 }
122 }
123
124 stop_source __stop_source_;
125 thread __thread_;
126};
127
128_LIBCPP_END_NAMESPACE_STD
129
130#endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
131
132_LIBCPP_POP_MACROS
133
134#endif // _LIBCPP___THREAD_JTHREAD_H
135