11.2.0/bits/std_thread.h

// std::thread declarations -*- C++ -*-

// 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
// 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 bits/std_thread.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{thread}
 */

#ifndef _GLIBCXX_THREAD_H
#define _GLIBCXX_THREAD_H 1

#pragma GCC system_header

#if __cplusplus >= 201103L
#include <bits/c++config.h>

#include <exception>            // std::terminate
#include <iosfwd>               // std::basic_ostream
#include <tuple>                // std::tuple
#include <bits/functional_hash.h> // std::hash
#include <bits/invoke.h>        // std::__invoke
#include <bits/refwrap.h>       // not required, but helpful to users
#include <bits/unique_ptr.h>    // std::unique_ptr

#ifdef _GLIBCXX_HAS_GTHREADS
# include <bits/gthr.h>
#else
# include <errno.h>
# include <bits/functexcept.h>
#endif

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /** @addtogroup threads
   *  @{
   */

  /// thread
  class thread
  {
  public:
#ifdef _GLIBCXX_HAS_GTHREADS
    // 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>;

    using native_handle_type = __gthread_t;
#else
    using native_handle_type = int;
#endif

    /// 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 struct 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;

#ifdef _GLIBCXX_HAS_GTHREADS
    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
        using _Wrapper = _Call_wrapper<_Callable, _Args...>;
        // Create a call wrapper with DECAY_COPY(__f) as its target object
        // and DECAY_COPY(__args)... as its bound argument entities.
        _M_start_thread(_State_ptr(new _State_impl<_Wrapper>(
              std::forward<_Callable>(__f), std::forward<_Args>(__args)...)),
            __depend);
      }
#endif // _GLIBCXX_HAS_GTHREADS

    ~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;

#ifdef _GLIBCXX_HAS_GTHREADS
  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 (*)());

#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());
        }
      };

  public:
    template<typename... _Tp>
      using _Call_wrapper = _Invoker<tuple<typename decay<_Tp>::type...>>;
#endif // _GLIBCXX_HAS_GTHREADS
  };

#ifndef _GLIBCXX_HAS_GTHREADS
  inline void thread::join() { std::__throw_system_error(EINVAL); }
  inline void thread::detach() { std::__throw_system_error(EINVAL); }
  inline unsigned int thread::hardware_concurrency() noexcept { return 0; }
#endif

  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;
  }

  // N.B. other comparison operators are defined in <thread>

  // 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); }
    };

  namespace this_thread
  {
    /// this_thread::get_id
    inline thread::id
    get_id() noexcept
    {
#ifndef _GLIBCXX_HAS_GTHREADS
      return thread::id(1);
#elif defined _GLIBCXX_NATIVE_THREAD_ID
      return thread::id(_GLIBCXX_NATIVE_THREAD_ID);
#else
      return thread::id(__gthread_self());
#endif
    }

    /// this_thread::yield
    inline void
    yield() noexcept
    {
#if defined _GLIBCXX_HAS_GTHREADS && defined _GLIBCXX_USE_SCHED_YIELD
      __gthread_yield();
#endif
    }

  } // namespace this_thread

  /// @}

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // C++11

#endif // _GLIBCXX_THREAD_H
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	8469 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// std::thread declarations -- C++ --
2
3	// Copyright (C) 2008-2021 Free Software Foundation, Inc.
4	//
5	// This file is part of the GNU ISO C++ Library. This library is free
6	// software; you can redistribute it and/or modify it under the
7	// terms of the GNU General Public License as published by the
8	// Free Software Foundation; either version 3, or (at your option)
9	// any later version.
10
11	// This library is distributed in the hope that it will be useful,
12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	// GNU General Public License for more details.
15
16	// Under Section 7 of GPL version 3, you are granted additional
17	// permissions described in the GCC Runtime Library Exception, version
18	// 3.1, as published by the Free Software Foundation.
19
20	// You should have received a copy of the GNU General Public License and
21	// a copy of the GCC Runtime Library Exception along with this program;
22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23	// <http://www.gnu.org/licenses/>.
24
25	/** @file bits/std_thread.h
26	* This is an internal header file, included by other library headers.
27	* Do not attempt to use it directly. @headername{thread}
28	*/
29
30	#ifndef _GLIBCXX_THREAD_H
31	#define _GLIBCXX_THREAD_H 1
32
33	#pragma GCC system_header
34
35	#if __cplusplus >= 201103L
36	#include <bits/c++config.h>
37
38	#include <exception> // std::terminate
39	#include <iosfwd> // std::basic_ostream
40	#include <tuple> // std::tuple
41	#include <bits/functional_hash.h> // std::hash
42	#include <bits/invoke.h> // std::__invoke
43	#include <bits/refwrap.h> // not required, but helpful to users
44	#include <bits/unique_ptr.h> // std::unique_ptr
45
46	#ifdef _GLIBCXX_HAS_GTHREADS
47	# include <bits/gthr.h>
48	#else
49	# include <errno.h>
50	# include <bits/functexcept.h>
51	#endif
52
53	namespace std _GLIBCXX_VISIBILITY(default)
54	{
55	_GLIBCXX_BEGIN_NAMESPACE_VERSION
56
57	/** @addtogroup threads
58	* @{
59	*/
60
61	/// thread
62	class thread
63	{
64	public:
65	#ifdef _GLIBCXX_HAS_GTHREADS
66	// Abstract base class for types that wrap arbitrary functors to be
67	// invoked in the new thread of execution.
68	struct _State
69	{
70	virtual ~_State();
71	virtual void _M_run() = 0;
72	};
73	using _State_ptr = unique_ptr<_State>;
74
75	using native_handle_type = __gthread_t;
76	#else
77	using native_handle_type = int;
78	#endif
79
80	/// thread::id
81	class id
82	{
83	native_handle_type _M_thread;
84
85	public:
86	id() noexcept : _M_thread() { }
87
88	explicit
89	id(native_handle_type __id) : _M_thread(__id) { }
90
91	private:
92	friend class thread;
93	friend struct hash<id>;
94
95	friend bool
96	operator==(id __x, id __y) noexcept;
97
98	#if __cpp_lib_three_way_comparison
99	friend strong_ordering
100	operator<=>(id __x, id __y) noexcept;
101	#else
102	friend bool
103	operator<(id __x, id __y) noexcept;
104	#endif
105
106	template<class _CharT, class _Traits>
107	friend basic_ostream<_CharT, _Traits>&
108	operator<<(basic_ostream<_CharT, _Traits>& __out, id __id);
109	};
110
111	private:
112	id _M_id;
113
114	// _GLIBCXX_RESOLVE_LIB_DEFECTS
115	// 2097. packaged_task constructors should be constrained
116	// 3039. Unnecessary decay in thread and packaged_task
117	template<typename _Tp>
118	using __not_same = __not_<is_same<__remove_cvref_t<_Tp>, thread>>;
119
120	public:
121	thread() noexcept = default;
122
123	#ifdef _GLIBCXX_HAS_GTHREADS
124	template<typename _Callable, typename... _Args,
125	typename = _Require<__not_same<_Callable>>>
126	explicit
127	thread(_Callable&& __f, _Args&&... __args)
128	{
129	static_assert( __is_invocable<typename decay<_Callable>::type,
130	typename decay<_Args>::type...>::value,
131	"std::thread arguments must be invocable after conversion to rvalues"
132	);
133
134	#ifdef GTHR_ACTIVE_PROXY
135	// Create a reference to pthread_create, not just the gthr weak symbol.
136	auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
137	#else
138	auto __depend = nullptr;
139	#endif
140	using _Wrapper = _Call_wrapper<_Callable, _Args...>;
141	// Create a call wrapper with DECAY_COPY(__f) as its target object
142	// and DECAY_COPY(__args)... as its bound argument entities.
143	_M_start_thread(_State_ptr(new _State_impl<_Wrapper>(
144	std::forward<_Callable>(__f), std::forward<_Args>(__args)...)),
145	__depend);
146	}
147	#endif // _GLIBCXX_HAS_GTHREADS
148
149	~thread()
150	{
151	if (joinable())
152	std::terminate();
153	}
154
155	thread(const thread&) = delete;
156
157	thread(thread&& __t) noexcept
158	{ swap(__t); }
159
160	thread& operator=(const thread&) = delete;
161
162	thread& operator=(thread&& __t) noexcept
163	{
164	if (joinable())
165	std::terminate();
166	swap(__t);
167	return *this;
168	}
169
170	void
171	swap(thread& __t) noexcept
172	{ std::swap(_M_id, __t._M_id); }
173
174	bool
175	joinable() const noexcept
176	{ return !(_M_id == id()); }
177
178	void
179	join();
180
181	void
182	detach();
183
184	id
185	get_id() const noexcept
186	{ return _M_id; }
187
188	/** @pre thread is joinable
189	*/
190	native_handle_type
191	native_handle()
192	{ return _M_id._M_thread; }
193
194	// Returns a value that hints at the number of hardware thread contexts.
195	static unsigned int
196	hardware_concurrency() noexcept;
197
198	#ifdef _GLIBCXX_HAS_GTHREADS
199	private:
200	template<typename _Callable>
201	struct _State_impl : public _State
202	{
203	_Callable _M_func;
204
205	template<typename... _Args>
206	_State_impl(_Args&&... __args)
207	: _M_func{{std::forward<_Args>(__args)...}}
208	{ }
209
210	void
211	_M_run() { _M_func(); }
212	};
213
214	void
215	_M_start_thread(_State_ptr, void (*)());
216
217	#if _GLIBCXX_THREAD_ABI_COMPAT
218	public:
219	struct _Impl_base;
220	typedef shared_ptr<_Impl_base> __shared_base_type;
221	struct _Impl_base
222	{
223	__shared_base_type _M_this_ptr;
224	virtual ~_Impl_base() = default;
225	virtual void _M_run() = 0;
226	};
227
228	private:
229	void
230	_M_start_thread(__shared_base_type, void (*)());
231
232	void
233	_M_start_thread(__shared_base_type);
234	#endif
235
236	private:
237	// A call wrapper that does INVOKE(forwarded tuple elements...)
238	template<typename _Tuple>
239	struct _Invoker
240	{
241	_Tuple _M_t;
242
243	template<typename>
244	struct __result;
245	template<typename _Fn, typename... _Args>
246	struct __result<tuple<_Fn, _Args...>>
247	: __invoke_result<_Fn, _Args...>
248	{ };
249
250	template<size_t... _Ind>
251	typename __result<_Tuple>::type
252	_M_invoke(_Index_tuple<_Ind...>)
253	{ return std::__invoke(std::get<_Ind>(std::move(_M_t))...); }
254
255	typename __result<_Tuple>::type
256	operator()()
257	{
258	using _Indices
259	= typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type;
260	return _M_invoke(_Indices());
261	}
262	};
263
264	public:
265	template<typename... _Tp>
266	using _Call_wrapper = _Invoker<tuple<typename decay<_Tp>::type...>>;
267	#endif // _GLIBCXX_HAS_GTHREADS
268	};
269
270	#ifndef _GLIBCXX_HAS_GTHREADS
271	inline void thread::join() { std::__throw_system_error(EINVAL); }
272	inline void thread::detach() { std::__throw_system_error(EINVAL); }
273	inline unsigned int thread::hardware_concurrency() noexcept { return 0; }
274	#endif
275
276	inline void
277	swap(thread& __x, thread& __y) noexcept
278	{ __x.swap(__y); }
279
280	inline bool
281	operator==(thread::id __x, thread::id __y) noexcept
282	{
283	// pthread_equal is undefined if either thread ID is not valid, so we
284	// can't safely use __gthread_equal on default-constructed values (nor
285	// the non-zero value returned by this_thread::get_id() for
286	// single-threaded programs using GNU libc). Assume EqualityComparable.
287	return __x._M_thread == __y._M_thread;
288	}
289
290	// N.B. other comparison operators are defined in <thread>
291
292	// DR 889.
293	/// std::hash specialization for thread::id.
294	template<>
295	struct hash<thread::id>
296	: public __hash_base<size_t, thread::id>
297	{
298	size_t
299	operator()(const thread::id& __id) const noexcept
300	{ return std::_Hash_impl::hash(__id._M_thread); }
301	};
302
303	namespace this_thread
304	{
305	/// this_thread::get_id
306	inline thread::id
307	get_id() noexcept
308	{
309	#ifndef _GLIBCXX_HAS_GTHREADS
310	return thread::id(1);
311	#elif defined _GLIBCXX_NATIVE_THREAD_ID
312	return thread::id(_GLIBCXX_NATIVE_THREAD_ID);
313	#else
314	return thread::id(__gthread_self());
315	#endif
316	}
317
318	/// this_thread::yield
319	inline void
320	yield() noexcept
321	{
322	#if defined _GLIBCXX_HAS_GTHREADS && defined _GLIBCXX_USE_SCHED_YIELD
323	__gthread_yield();
324	#endif
325	}
326
327	} // namespace this_thread
328
329	/// @}
330
331	_GLIBCXX_END_NAMESPACE_VERSION
332	} // namespace
333	#endif // C++11
334
335	#endif // _GLIBCXX_THREAD_H