// <thread> -*- C++ -*- // Copyright (C) 2008-2020 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file include/thread * This is a Standard C++ Library header. */ #ifndef _GLIBCXX_THREAD #define _GLIBCXX_THREAD 1 #pragma GCC system_header #if __cplusplus < 201103L # include <bits/c++0x_warning.h> #else #include <bits/c++config.h> #if defined(_GLIBCXX_HAS_GTHREADS) #include <bits/gthr.h> #include <chrono> // std::chrono::* #include <memory> // std::unique_ptr #include <tuple> // std::tuple #if __cplusplus > 201703L # include <compare> // std::strong_ordering # include <stop_token> // std::stop_source, std::stop_token, std::nostopstate #endif #ifdef _GLIBCXX_USE_NANOSLEEP # include <cerrno> // errno, EINTR # include <time.h> // nanosleep #endif #include <bits/functional_hash.h> // std::hash #include <bits/invoke.h> // std::__invoke namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION /** * @defgroup threads Threads * @ingroup concurrency * * Classes for thread support. * @{ */ /// thread class thread { public: // Abstract base class for types that wrap arbitrary functors to be // invoked in the new thread of execution. struct _State { virtual ~_State(); virtual void _M_run() = 0; }; using _State_ptr = unique_ptr<_State>; typedef __gthread_t native_handle_type; /// thread::id class id { native_handle_type _M_thread; public: id() noexcept : _M_thread() { } explicit id(native_handle_type __id) : _M_thread(__id) { } private: friend class thread; friend class hash<id>; friend bool operator==(id __x, id __y) noexcept; #if __cpp_lib_three_way_comparison friend strong_ordering operator<=>(id __x, id __y) noexcept; #else friend bool operator<(id __x, id __y) noexcept; #endif template<class _CharT, class _Traits> friend basic_ostream<_CharT, _Traits>& operator<<(basic_ostream<_CharT, _Traits>& __out, id __id); }; private: id _M_id; // _GLIBCXX_RESOLVE_LIB_DEFECTS // 2097. packaged_task constructors should be constrained // 3039. Unnecessary decay in thread and packaged_task template<typename _Tp> using __not_same = __not_<is_same<__remove_cvref_t<_Tp>, thread>>; public: thread() noexcept = default; template<typename _Callable, typename... _Args, typename = _Require<__not_same<_Callable>>> explicit thread(_Callable&& __f, _Args&&... __args) { static_assert( __is_invocable<typename decay<_Callable>::type, typename decay<_Args>::type...>::value, "std::thread arguments must be invocable after conversion to rvalues" ); #ifdef GTHR_ACTIVE_PROXY // Create a reference to pthread_create, not just the gthr weak symbol. auto __depend = reinterpret_cast<void(*)()>(&pthread_create); #else auto __depend = nullptr; #endif // A call wrapper holding tuple{DECAY_COPY(__f), DECAY_COPY(__args)...} using _Invoker_type = _Invoker<__decayed_tuple<_Callable, _Args...>>; _M_start_thread(_S_make_state<_Invoker_type>( std::forward<_Callable>(__f), std::forward<_Args>(__args)...), __depend); } ~thread() { if (joinable()) std::terminate(); } thread(const thread&) = delete; thread(thread&& __t) noexcept { swap(__t); } thread& operator=(const thread&) = delete; thread& operator=(thread&& __t) noexcept { if (joinable()) std::terminate(); swap(__t); return *this; } void swap(thread& __t) noexcept { std::swap(_M_id, __t._M_id); } bool joinable() const noexcept { return !(_M_id == id()); } void join(); void detach(); id get_id() const noexcept { return _M_id; } /** @pre thread is joinable */ native_handle_type native_handle() { return _M_id._M_thread; } // Returns a value that hints at the number of hardware thread contexts. static unsigned int hardware_concurrency() noexcept; private: template<typename _Callable> struct _State_impl : public _State { _Callable _M_func; template<typename... _Args> _State_impl(_Args&&... __args) : _M_func{{std::forward<_Args>(__args)...}} { } void _M_run() { _M_func(); } }; void _M_start_thread(_State_ptr, void (*)()); template<typename _Callable, typename... _Args> static _State_ptr _S_make_state(_Args&&... __args) { using _Impl = _State_impl<_Callable>; return _State_ptr{new _Impl{std::forward<_Args>(__args)...}}; } #if _GLIBCXX_THREAD_ABI_COMPAT public: struct _Impl_base; typedef shared_ptr<_Impl_base> __shared_base_type; struct _Impl_base { __shared_base_type _M_this_ptr; virtual ~_Impl_base() = default; virtual void _M_run() = 0; }; private: void _M_start_thread(__shared_base_type, void (*)()); void _M_start_thread(__shared_base_type); #endif private: // A call wrapper that does INVOKE(forwarded tuple elements...) template<typename _Tuple> struct _Invoker { _Tuple _M_t; template<typename> struct __result; template<typename _Fn, typename... _Args> struct __result<tuple<_Fn, _Args...>> : __invoke_result<_Fn, _Args...> { }; template<size_t... _Ind> typename __result<_Tuple>::type _M_invoke(_Index_tuple<_Ind...>) { return std::__invoke(std::get<_Ind>(std::move(_M_t))...); } typename __result<_Tuple>::type operator()() { using _Indices = typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type; return _M_invoke(_Indices()); } }; template<typename... _Tp> using __decayed_tuple = tuple<typename decay<_Tp>::type...>; public: // Returns a call wrapper that stores // tuple{DECAY_COPY(__callable), DECAY_COPY(__args)...}. template<typename _Callable, typename... _Args> static _Invoker<__decayed_tuple<_Callable, _Args...>> __make_invoker(_Callable&& __callable, _Args&&... __args) { return { __decayed_tuple<_Callable, _Args...>{ std::forward<_Callable>(__callable), std::forward<_Args>(__args)... } }; } }; inline void swap(thread& __x, thread& __y) noexcept { __x.swap(__y); } inline bool operator==(thread::id __x, thread::id __y) noexcept { // pthread_equal is undefined if either thread ID is not valid, so we // can't safely use __gthread_equal on default-constructed values (nor // the non-zero value returned by this_thread::get_id() for // single-threaded programs using GNU libc). Assume EqualityComparable. return __x._M_thread == __y._M_thread; } #if __cpp_lib_three_way_comparison inline strong_ordering operator<=>(thread::id __x, thread::id __y) noexcept { return __x._M_thread <=> __y._M_thread; } #else inline bool operator!=(thread::id __x, thread::id __y) noexcept { return !(__x == __y); } inline bool operator<(thread::id __x, thread::id __y) noexcept { // Pthreads doesn't define any way to do this, so we just have to // assume native_handle_type is LessThanComparable. return __x._M_thread < __y._M_thread; } inline bool operator<=(thread::id __x, thread::id __y) noexcept { return !(__y < __x); } inline bool operator>(thread::id __x, thread::id __y) noexcept { return __y < __x; } inline bool operator>=(thread::id __x, thread::id __y) noexcept { return !(__x < __y); } #endif // __cpp_lib_three_way_comparison // DR 889. /// std::hash specialization for thread::id. template<> struct hash<thread::id> : public __hash_base<size_t, thread::id> { size_t operator()(const thread::id& __id) const noexcept { return std::_Hash_impl::hash(__id._M_thread); } }; template<class _CharT, class _Traits> inline basic_ostream<_CharT, _Traits>& operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id) { if (__id == thread::id()) return __out << "thread::id of a non-executing thread"; else return __out << __id._M_thread; } /** @namespace std::this_thread * @brief ISO C++ 2011 namespace for interacting with the current thread * * C++11 30.3.2 [thread.thread.this] Namespace this_thread. */ namespace this_thread { /// get_id inline thread::id get_id() noexcept { #ifdef _GLIBCXX_NATIVE_THREAD_ID return thread::id(_GLIBCXX_NATIVE_THREAD_ID); #else return thread::id(__gthread_self()); #endif } /// yield inline void yield() noexcept { #ifdef _GLIBCXX_USE_SCHED_YIELD __gthread_yield(); #endif } void __sleep_for(chrono::seconds, chrono::nanoseconds); /// sleep_for template<typename _Rep, typename _Period> inline void sleep_for(const chrono::duration<_Rep, _Period>& __rtime) { if (__rtime <= __rtime.zero()) return; auto __s = chrono::duration_cast<chrono::seconds>(__rtime); auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s); #ifdef _GLIBCXX_USE_NANOSLEEP __gthread_time_t __ts = { static_cast<std::time_t>(__s.count()), static_cast<long>(__ns.count()) }; while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR) { } #else __sleep_for(__s, __ns); #endif } /// sleep_until template<typename _Clock, typename _Duration> inline void sleep_until(const chrono::time_point<_Clock, _Duration>& __atime) { #if __cplusplus > 201703L static_assert(chrono::is_clock_v<_Clock>); #endif auto __now = _Clock::now(); if (_Clock::is_steady) { if (__now < __atime) sleep_for(__atime - __now); return; } while (__now < __atime) { sleep_for(__atime - __now); __now = _Clock::now(); } } } // @} group threads #ifdef __cpp_lib_jthread class jthread { public: using id = thread::id; using native_handle_type = thread::native_handle_type; jthread() noexcept : _M_stop_source{nostopstate} { } template<typename _Callable, typename... _Args, typename = enable_if_t<!is_same_v<remove_cvref_t<_Callable>, jthread>>> explicit jthread(_Callable&& __f, _Args&&... __args) : _M_thread{_S_create(_M_stop_source, std::forward<_Callable>(__f), std::forward<_Args>(__args)...)} { } jthread(const jthread&) = delete; jthread(jthread&&) noexcept = default; ~jthread() { if (joinable()) { request_stop(); join(); } } jthread& operator=(const jthread&) = delete; jthread& operator=(jthread&& __other) noexcept { std::jthread(std::move(__other)).swap(*this); return *this; } void swap(jthread& __other) noexcept { std::swap(_M_stop_source, __other._M_stop_source); std::swap(_M_thread, __other._M_thread); } [[nodiscard]] bool joinable() const noexcept { return _M_thread.joinable(); } void join() { _M_thread.join(); } void detach() { _M_thread.detach(); } [[nodiscard]] id get_id() const noexcept { return _M_thread.get_id(); } [[nodiscard]] native_handle_type native_handle() { return _M_thread.native_handle(); } [[nodiscard]] static unsigned hardware_concurrency() noexcept { return thread::hardware_concurrency(); } [[nodiscard]] stop_source get_stop_source() noexcept { return _M_stop_source; } [[nodiscard]] stop_token get_stop_token() const noexcept { return _M_stop_source.get_token(); } bool request_stop() noexcept { return _M_stop_source.request_stop(); } friend void swap(jthread& __lhs, jthread& __rhs) noexcept { __lhs.swap(__rhs); } private: template<typename _Callable, typename... _Args> static thread _S_create(stop_source& __ssrc, _Callable&& __f, _Args&&... __args) { if constexpr(is_invocable_v<decay_t<_Callable>, stop_token, decay_t<_Args>...>) return thread{std::forward<_Callable>(__f), __ssrc.get_token(), std::forward<_Args>(__args)...}; else { static_assert(is_invocable_v<decay_t<_Callable>, decay_t<_Args>...>, "std::thread arguments must be invocable after" " conversion to rvalues"); return thread{std::forward<_Callable>(__f), std::forward<_Args>(__args)...}; } } stop_source _M_stop_source; thread _M_thread; }; #endif // __cpp_lib_jthread _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif // _GLIBCXX_HAS_GTHREADS #endif // C++11 #endif // _GLIBCXX_THREAD