// <thread> -*- C++ -*-
-// Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2008-2021 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
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
-/** @file thread
+/** @file include/thread
* This is a Standard C++ Library header.
*/
#pragma GCC system_header
-#ifndef __GXX_EXPERIMENTAL_CXX0X__
+#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
-#include <chrono>
-#include <functional>
-#include <memory>
-#include <mutex>
-#include <condition_variable>
-#include <bits/functexcept.h>
-#include <bits/functional_hash.h>
-#include <bits/gthr.h>
+#include <chrono> // std::chrono::*
-#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
+#if __cplusplus > 201703L
+# include <compare> // std::strong_ordering
+# include <stop_token> // std::stop_source, std::stop_token, std::nostopstate
+#endif
+
+#include <bits/std_thread.h> // std::thread, get_id, yield
+
+#ifdef _GLIBCXX_USE_NANOSLEEP
+# include <cerrno> // errno, EINTR
+# include <time.h> // nanosleep
+#endif
-namespace std
+namespace std _GLIBCXX_VISIBILITY(default)
{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
/**
* @defgroup threads Threads
* @ingroup concurrency
* @{
*/
- template<typename _Tp>
- struct hash;
-
- /// thread
- class thread
- {
- public:
- typedef __gthread_t native_handle_type;
- struct _Impl_base;
- typedef shared_ptr<_Impl_base> __shared_base_type;
-
- /// thread::id
- class id
- {
- native_handle_type _M_thread;
-
- public:
- id() : _M_thread() { }
+ // std::thread is defined in <bits/std_thread.h>
- explicit
- id(native_handle_type __id) : _M_thread(__id) { }
+#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); }
- private:
- friend class thread;
- friend class hash<thread::id>;
+ 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;
+ }
- friend bool
- operator==(thread::id __x, thread::id __y)
- { return __gthread_equal(__x._M_thread, __y._M_thread); }
+ inline bool
+ operator<=(thread::id __x, thread::id __y) noexcept
+ { return !(__y < __x); }
- friend bool
- operator<(thread::id __x, thread::id __y)
- { return __x._M_thread < __y._M_thread; }
+ inline bool
+ operator>(thread::id __x, thread::id __y) noexcept
+ { return __y < __x; }
- template<class _CharT, class _Traits>
- friend basic_ostream<_CharT, _Traits>&
- operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id);
- };
+ inline bool
+ operator>=(thread::id __x, thread::id __y) noexcept
+ { return !(__x < __y); }
+#endif // __cpp_lib_three_way_comparison
- // Simple base type that the templatized, derived class containing
- // an arbitrary functor can be converted to and called.
- struct _Impl_base
+ template<class _CharT, class _Traits>
+ inline basic_ostream<_CharT, _Traits>&
+ operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
{
- __shared_base_type _M_this_ptr;
+ if (__id == thread::id())
+ return __out << "thread::id of a non-executing thread";
+ else
+ return __out << __id._M_thread;
+ }
- inline virtual ~_Impl_base();
+ /** @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
+ {
+#ifndef _GLIBCXX_NO_SLEEP
- virtual void _M_run() = 0;
- };
+#ifndef _GLIBCXX_USE_NANOSLEEP
+ void
+ __sleep_for(chrono::seconds, chrono::nanoseconds);
+#endif
- template<typename _Callable>
- struct _Impl : public _Impl_base
+ /// this_thread::sleep_for
+ template<typename _Rep, typename _Period>
+ inline void
+ sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
{
- _Callable _M_func;
-
- _Impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f))
- { }
+ 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
+ struct ::timespec __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
+ }
- void
- _M_run() { _M_func(); }
- };
+ /// this_thread::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();
+ }
+ }
+ } // namespace this_thread
+#endif // ! NO_SLEEP
- private:
- id _M_id;
+#ifdef __cpp_lib_jthread
+ /// A thread that can be requested to stop and automatically joined.
+ class jthread
+ {
public:
- thread() = default;
- thread(const thread&) = delete;
+ using id = thread::id;
+ using native_handle_type = thread::native_handle_type;
- thread(thread&& __t)
- { swap(__t); }
+ jthread() noexcept
+ : _M_stop_source{nostopstate}
+ { }
- template<typename _Callable>
- explicit thread(_Callable __f)
- {
- _M_start_thread(_M_make_routine<_Callable>
- (std::forward<_Callable>(__f)));
- }
+ 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)...)}
+ { }
- template<typename _Callable, typename... _Args>
- thread(_Callable&& __f, _Args&&... __args)
- { _M_start_thread(_M_make_routine(std::bind(__f, __args...))); }
+ jthread(const jthread&) = delete;
+ jthread(jthread&&) noexcept = default;
- ~thread()
+ ~jthread()
{
if (joinable())
- std::terminate();
+ {
+ request_stop();
+ join();
+ }
}
- thread& operator=(const thread&) = delete;
+ jthread&
+ operator=(const jthread&) = delete;
- thread& operator=(thread&& __t)
+ jthread&
+ operator=(jthread&& __other) noexcept
{
- if (joinable())
- std::terminate();
- swap(__t);
+ std::jthread(std::move(__other)).swap(*this);
return *this;
}
void
- swap(thread& __t)
- { std::swap(_M_id, __t._M_id); }
+ swap(jthread& __other) noexcept
+ {
+ std::swap(_M_stop_source, __other._M_stop_source);
+ std::swap(_M_thread, __other._M_thread);
+ }
- bool
- joinable() const
- { return !(_M_id == id()); }
+ [[nodiscard]] bool
+ joinable() const noexcept
+ {
+ return _M_thread.joinable();
+ }
void
- join();
+ join()
+ {
+ _M_thread.join();
+ }
void
- detach();
+ detach()
+ {
+ _M_thread.detach();
+ }
- thread::id
- get_id() const
- { return _M_id; }
+ [[nodiscard]] id
+ get_id() const noexcept
+ {
+ return _M_thread.get_id();
+ }
- /** @pre thread is joinable
- */
- native_handle_type
+ [[nodiscard]] 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()
- { return 0; }
-
- private:
- void
- _M_start_thread(__shared_base_type);
-
- template<typename _Callable>
- shared_ptr<_Impl<_Callable>>
- _M_make_routine(_Callable&& __f)
- {
- // Create and allocate full data structure, not base.
- return make_shared<_Impl<_Callable>>(std::forward<_Callable>(__f));
- }
- };
-
- inline thread::_Impl_base::~_Impl_base() = default;
-
- inline void
- swap(thread& __x, thread& __y)
- { __x.swap(__y); }
-
- inline bool
- operator!=(thread::id __x, thread::id __y)
- { return !(__x == __y); }
-
- inline bool
- operator<=(thread::id __x, thread::id __y)
- { return !(__y < __x); }
-
- inline bool
- operator>(thread::id __x, thread::id __y)
- { return __y < __x; }
+ {
+ return _M_thread.native_handle();
+ }
- inline bool
- operator>=(thread::id __x, thread::id __y)
- { return !(__x < __y); }
+ [[nodiscard]] static unsigned
+ hardware_concurrency() noexcept
+ {
+ return thread::hardware_concurrency();
+ }
- // DR 889.
- /// std::hash specialization for thread::id.
- template<>
- struct hash<thread::id>
- : public std::unary_function<thread::id, size_t>
+ [[nodiscard]] stop_source
+ get_stop_source() noexcept
{
- size_t
- operator()(const thread::id& __id) const
- { return std::_Fnv_hash::hash(__id._M_thread); }
- };
+ return _M_stop_source;
+ }
- template<class _CharT, class _Traits>
- inline basic_ostream<_CharT, _Traits>&
- operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
+ [[nodiscard]] stop_token
+ get_stop_token() const noexcept
{
- if (__id == thread::id())
- return __out << "thread::id of a non-executing thread";
- else
- return __out << __id._M_thread;
+ return _M_stop_source.get_token();
}
- /** @namespace std::this_thread
- * @brief ISO C++ 0x entities sub namespace for thread.
- * 30.2.2 Namespace this_thread.
- */
- namespace this_thread
- {
- /// get_id
- inline thread::id
- get_id() { return thread::id(__gthread_self()); }
-
-#ifdef _GLIBCXX_USE_SCHED_YIELD
- /// yield
- inline void
- yield()
- { __gthread_yield(); }
-#endif
+ bool request_stop() noexcept
+ {
+ return _M_stop_source.request_stop();
+ }
-#ifdef _GLIBCXX_USE_NANOSLEEP
- /// sleep_until
- template<typename _Clock, typename _Duration>
- inline void
- sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
- { sleep_for(__atime - _Clock::now()); }
+ friend void swap(jthread& __lhs, jthread& __rhs) noexcept
+ {
+ __lhs.swap(__rhs);
+ }
- /// sleep_for
- template<typename _Rep, typename _Period>
- inline void
- sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
+ private:
+ template<typename _Callable, typename... _Args>
+ static thread
+ _S_create(stop_source& __ssrc, _Callable&& __f, _Args&&... __args)
{
- chrono::seconds __s =
- chrono::duration_cast<chrono::seconds>(__rtime);
-
- chrono::nanoseconds __ns =
- chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
-
- __gthread_time_t __ts =
+ 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_cast<std::time_t>(__s.count()),
- static_cast<long>(__ns.count())
- };
-
- ::nanosleep(&__ts, 0);
+ 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)...};
+ }
}
-#endif
- }
- // @} group threads
-}
-
-#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
+ stop_source _M_stop_source;
+ thread _M_thread;
+ };
+#endif // __cpp_lib_jthread
-#endif // __GXX_EXPERIMENTAL_CXX0X__
+ // @} group threads
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+#endif // C++11
#endif // _GLIBCXX_THREAD
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