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