1// <thread> -*- C++ -*-
2
3// Copyright (C) 2008-2016 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 include/thread
26 *  This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_THREAD
30#define _GLIBCXX_THREAD 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <chrono>
39#include <functional>
40#include <memory>
41#include <cerrno>
42#include <bits/functexcept.h>
43#include <bits/functional_hash.h>
44#include <bits/gthr.h>
45
46#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
47
48namespace std _GLIBCXX_VISIBILITY(default)
49{
50_GLIBCXX_BEGIN_NAMESPACE_VERSION
51
52  /**
53   * @defgroup threads Threads
54   * @ingroup concurrency
55   *
56   * Classes for thread support.
57   * @{
58   */
59
60  /// thread
61  class thread
62  {
63  public:
64    // Abstract base class for types that wrap arbitrary functors to be
65    // invoked in the new thread of execution.
66    struct _State
67    {
68      virtual ~_State();
69      virtual void _M_run() = 0;
70    };
71    using _State_ptr = unique_ptr<_State>;
72
73    typedef __gthread_t			native_handle_type;
74
75    /// thread::id
76    class id
77    {
78      native_handle_type	_M_thread;
79
80    public:
81      id() noexcept : _M_thread() { }
82
83      explicit
84      id(native_handle_type __id) : _M_thread(__id) { }
85
86    private:
87      friend class thread;
88      friend class hash<thread::id>;
89
90      friend bool
91      operator==(thread::id __x, thread::id __y) noexcept
92      {
93	// pthread_equal is undefined if either thread ID is not valid, so we
94	// can't safely use __gthread_equal on default-constructed values (nor
95	// the non-zero value returned by this_thread::get_id() for
96	// single-threaded programs using GNU libc). Assume EqualityComparable.
97	return __x._M_thread == __y._M_thread;
98      }
99
100      friend bool
101      operator<(thread::id __x, thread::id __y) noexcept
102      {
103	// Pthreads doesn't define any way to do this, so we just have to
104	// assume native_handle_type is LessThanComparable.
105	return __x._M_thread < __y._M_thread;
106      }
107
108      template<class _CharT, class _Traits>
109	friend basic_ostream<_CharT, _Traits>&
110	operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id);
111    };
112
113  private:
114    id				_M_id;
115
116  public:
117    thread() noexcept = default;
118    // _GLIBCXX_RESOLVE_LIB_DEFECTS
119    // 2097.  packaged_task constructors should be constrained
120    thread(thread&) = delete;
121    thread(const thread&) = delete;
122    thread(const thread&&) = delete;
123
124    thread(thread&& __t) noexcept
125    { swap(__t); }
126
127    template<typename _Callable, typename... _Args>
128      explicit
129      thread(_Callable&& __f, _Args&&... __args)
130      {
131#ifdef GTHR_ACTIVE_PROXY
132	// Create a reference to pthread_create, not just the gthr weak symbol.
133	auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
134#else
135	auto __depend = nullptr;
136#endif
137        _M_start_thread(_S_make_state(
138	      std::__bind_simple(std::forward<_Callable>(__f),
139				 std::forward<_Args>(__args)...)),
140	    __depend);
141      }
142
143    ~thread()
144    {
145      if (joinable())
146	std::terminate();
147    }
148
149    thread& operator=(const thread&) = delete;
150
151    thread& operator=(thread&& __t) noexcept
152    {
153      if (joinable())
154	std::terminate();
155      swap(__t);
156      return *this;
157    }
158
159    void
160    swap(thread& __t) noexcept
161    { std::swap(_M_id, __t._M_id); }
162
163    bool
164    joinable() const noexcept
165    { return !(_M_id == id()); }
166
167    void
168    join();
169
170    void
171    detach();
172
173    thread::id
174    get_id() const noexcept
175    { return _M_id; }
176
177    /** @pre thread is joinable
178     */
179    native_handle_type
180    native_handle()
181    { return _M_id._M_thread; }
182
183    // Returns a value that hints at the number of hardware thread contexts.
184    static unsigned int
185    hardware_concurrency() noexcept;
186
187  private:
188    template<typename _Callable>
189      struct _State_impl : public _State
190      {
191	_Callable		_M_func;
192
193	_State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f))
194	{ }
195
196	void
197	_M_run() { _M_func(); }
198      };
199
200    void
201    _M_start_thread(_State_ptr, void (*)());
202
203    template<typename _Callable>
204      static _State_ptr
205      _S_make_state(_Callable&& __f)
206      {
207	using _Impl = _State_impl<_Callable>;
208	return _State_ptr{new _Impl{std::forward<_Callable>(__f)}};
209      }
210#if _GLIBCXX_THREAD_ABI_COMPAT
211  public:
212    struct _Impl_base;
213    typedef shared_ptr<_Impl_base>	__shared_base_type;
214    struct _Impl_base
215    {
216      __shared_base_type	_M_this_ptr;
217      virtual ~_Impl_base() = default;
218      virtual void _M_run() = 0;
219    };
220
221  private:
222    void
223    _M_start_thread(__shared_base_type, void (*)());
224
225    void
226    _M_start_thread(__shared_base_type);
227#endif
228  };
229
230  inline void
231  swap(thread& __x, thread& __y) noexcept
232  { __x.swap(__y); }
233
234  inline bool
235  operator!=(thread::id __x, thread::id __y) noexcept
236  { return !(__x == __y); }
237
238  inline bool
239  operator<=(thread::id __x, thread::id __y) noexcept
240  { return !(__y < __x); }
241
242  inline bool
243  operator>(thread::id __x, thread::id __y) noexcept
244  { return __y < __x; }
245
246  inline bool
247  operator>=(thread::id __x, thread::id __y) noexcept
248  { return !(__x < __y); }
249
250  // DR 889.
251  /// std::hash specialization for thread::id.
252  template<>
253    struct hash<thread::id>
254    : public __hash_base<size_t, thread::id>
255    {
256      size_t
257      operator()(const thread::id& __id) const noexcept
258      { return std::_Hash_impl::hash(__id._M_thread); }
259    };
260
261  template<class _CharT, class _Traits>
262    inline basic_ostream<_CharT, _Traits>&
263    operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
264    {
265      if (__id == thread::id())
266	return __out << "thread::id of a non-executing thread";
267      else
268	return __out << __id._M_thread;
269    }
270
271_GLIBCXX_END_NAMESPACE_VERSION
272
273  /** @namespace std::this_thread
274   *  @brief ISO C++ 2011 entities sub-namespace for thread.
275   *  30.3.2 Namespace this_thread.
276   */
277  namespace this_thread
278  {
279  _GLIBCXX_BEGIN_NAMESPACE_VERSION
280
281    /// get_id
282    inline thread::id
283    get_id() noexcept
284    {
285#ifdef L4__pthread_t_IS_NOT_AN_INT
286#ifdef __GLIBC__
287      // For the GNU C library pthread_self() is usable without linking to
288      // libpthread.so but returns 0, so we cannot use it in single-threaded
289      // programs, because this_thread::get_id() != thread::id{} must be true.
290      // We know that pthread_t is an integral type in the GNU C library.
291      if (!__gthread_active_p())
292	return thread::id(1);
293#endif
294#endif
295      return thread::id(__gthread_self());
296    }
297
298    /// yield
299    inline void
300    yield() noexcept
301    {
302#ifdef _GLIBCXX_USE_SCHED_YIELD
303      __gthread_yield();
304#endif
305    }
306
307    void
308    __sleep_for(chrono::seconds, chrono::nanoseconds);
309
310    /// sleep_for
311    template<typename _Rep, typename _Period>
312      inline void
313      sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
314      {
315	if (__rtime <= __rtime.zero())
316	  return;
317	auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
318	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
319#ifdef _GLIBCXX_USE_NANOSLEEP
320	__gthread_time_t __ts =
321	  {
322	    static_cast<std::time_t>(__s.count()),
323	    static_cast<long>(__ns.count())
324	  };
325	while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
326	  { }
327#else
328	__sleep_for(__s, __ns);
329#endif
330      }
331
332    /// sleep_until
333    template<typename _Clock, typename _Duration>
334      inline void
335      sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
336      {
337	auto __now = _Clock::now();
338	if (_Clock::is_steady)
339	  {
340	    if (__now < __atime)
341	      sleep_for(__atime - __now);
342	    return;
343	  }
344	while (__now < __atime)
345	  {
346	    sleep_for(__atime - __now);
347	    __now = _Clock::now();
348	  }
349      }
350
351  _GLIBCXX_END_NAMESPACE_VERSION
352  }
353
354  // @} group threads
355
356} // namespace
357
358#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
359
360#endif // C++11
361
362#endif // _GLIBCXX_THREAD
363