__cxx03/__thread/jthread.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___CXX03___THREAD_JTHREAD_H
0011 #define _LIBCPP___CXX03___THREAD_JTHREAD_H
0012
0013 #include <__cxx03/__config>
0014 #include <__cxx03/__functional/invoke.h>
0015 #include <__cxx03/__stop_token/stop_source.h>
0016 #include <__cxx03/__stop_token/stop_token.h>
0017 #include <__cxx03/__thread/support.h>
0018 #include <__cxx03/__thread/thread.h>
0019 #include <__cxx03/__type_traits/decay.h>
0020 #include <__cxx03/__type_traits/is_constructible.h>
0021 #include <__cxx03/__type_traits/is_same.h>
0022 #include <__cxx03/__type_traits/remove_cvref.h>
0023 #include <__cxx03/__utility/forward.h>
0024 #include <__cxx03/__utility/move.h>
0025
0026 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0027 #  pragma GCC system_header
0028 #endif
0029
0030 _LIBCPP_PUSH_MACROS
0031 #include <__cxx03/__undef_macros>
0032
0033 #if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
0034
0035 _LIBCPP_BEGIN_NAMESPACE_STD
0036
0037 class _LIBCPP_AVAILABILITY_SYNC jthread {
0038 public:
0039   // types
0040   using id                 = thread::id;
0041   using native_handle_type = thread::native_handle_type;
0042
0043   // [thread.jthread.cons], constructors, move, and assignment
0044   _LIBCPP_HIDE_FROM_ABI jthread() noexcept : __stop_source_(std::nostopstate) {}
0045
0046   template <class _Fun, class... _Args>
0047   _LIBCPP_HIDE_FROM_ABI explicit jthread(_Fun&& __fun, _Args&&... __args)
0048     requires(!std::is_same_v<remove_cvref_t<_Fun>, jthread>)
0049       : __stop_source_(),
0050         __thread_(__init_thread(__stop_source_, std::forward<_Fun>(__fun), std::forward<_Args>(__args)...)) {
0051     static_assert(is_constructible_v<decay_t<_Fun>, _Fun>);
0052     static_assert((is_constructible_v<decay_t<_Args>, _Args> && ...));
0053     static_assert(is_invocable_v<decay_t<_Fun>, decay_t<_Args>...> ||
0054                   is_invocable_v<decay_t<_Fun>, stop_token, decay_t<_Args>...>);
0055   }
0056
0057   _LIBCPP_HIDE_FROM_ABI ~jthread() {
0058     if (joinable()) {
0059       request_stop();
0060       join();
0061     }
0062   }
0063
0064   jthread(const jthread&) = delete;
0065
0066   _LIBCPP_HIDE_FROM_ABI jthread(jthread&&) noexcept = default;
0067
0068   jthread& operator=(const jthread&) = delete;
0069
0070   _LIBCPP_HIDE_FROM_ABI jthread& operator=(jthread&& __other) noexcept {
0071     if (this != &__other) {
0072       if (joinable()) {
0073         request_stop();
0074         join();
0075       }
0076       __stop_source_ = std::move(__other.__stop_source_);
0077       __thread_      = std::move(__other.__thread_);
0078     }
0079
0080     return *this;
0081   }
0082
0083   // [thread.jthread.mem], members
0084   _LIBCPP_HIDE_FROM_ABI void swap(jthread& __other) noexcept {
0085     std::swap(__stop_source_, __other.__stop_source_);
0086     std::swap(__thread_, __other.__thread_);
0087   }
0088
0089   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool joinable() const noexcept { return get_id() != id(); }
0090
0091   _LIBCPP_HIDE_FROM_ABI void join() { __thread_.join(); }
0092
0093   _LIBCPP_HIDE_FROM_ABI void detach() { __thread_.detach(); }
0094
0095   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI id get_id() const noexcept { return __thread_.get_id(); }
0096
0097   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return __thread_.native_handle(); }
0098
0099   // [thread.jthread.stop], stop token handling
0100   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI stop_source get_stop_source() noexcept { return __stop_source_; }
0101
0102   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI stop_token get_stop_token() const noexcept { return __stop_source_.get_token(); }
0103
0104   _LIBCPP_HIDE_FROM_ABI bool request_stop() noexcept { return __stop_source_.request_stop(); }
0105
0106   // [thread.jthread.special], specialized algorithms
0107   _LIBCPP_HIDE_FROM_ABI friend void swap(jthread& __lhs, jthread& __rhs) noexcept { __lhs.swap(__rhs); }
0108
0109   // [thread.jthread.static], static members
0110   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static unsigned int hardware_concurrency() noexcept {
0111     return thread::hardware_concurrency();
0112   }
0113
0114 private:
0115   template <class _Fun, class... _Args>
0116   _LIBCPP_HIDE_FROM_ABI static thread __init_thread(const stop_source& __ss, _Fun&& __fun, _Args&&... __args) {
0117     if constexpr (is_invocable_v<decay_t<_Fun>, stop_token, decay_t<_Args>...>) {
0118       return thread(std::forward<_Fun>(__fun), __ss.get_token(), std::forward<_Args>(__args)...);
0119     } else {
0120       return thread(std::forward<_Fun>(__fun), std::forward<_Args>(__args)...);
0121     }
0122   }
0123
0124   stop_source __stop_source_;
0125   thread __thread_;
0126 };
0127
0128 _LIBCPP_END_NAMESPACE_STD
0129
0130 #endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN)
0131
0132 _LIBCPP_POP_MACROS
0133
0134 #endif // _LIBCPP___CXX03___THREAD_JTHREAD_H