libstdc++
thread
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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 
48 namespace 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  };
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>
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
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>
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 __GLIBC__
286  // For the GNU C library pthread_self() is usable without linking to
287  // libpthread.so but returns 0, so we cannot use it in single-threaded
288  // programs, because this_thread::get_id() != thread::id{} must be true.
289  // We know that pthread_t is an integral type in the GNU C library.
290  if (!__gthread_active_p())
291  return thread::id(1);
292 #endif
293  return thread::id(__gthread_self());
294  }
295 
296  /// yield
297  inline void
298  yield() noexcept
299  {
300 #ifdef _GLIBCXX_USE_SCHED_YIELD
301  __gthread_yield();
302 #endif
303  }
304 
305  void
306  __sleep_for(chrono::seconds, chrono::nanoseconds);
307 
308  /// sleep_for
309  template<typename _Rep, typename _Period>
310  inline void
312  {
313  if (__rtime <= __rtime.zero())
314  return;
315  auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
316  auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
317 #ifdef _GLIBCXX_USE_NANOSLEEP
318  __gthread_time_t __ts =
319  {
320  static_cast<std::time_t>(__s.count()),
321  static_cast<long>(__ns.count())
322  };
323  while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
324  { }
325 #else
326  __sleep_for(__s, __ns);
327 #endif
328  }
329 
330  /// sleep_until
331  template<typename _Clock, typename _Duration>
332  inline void
334  {
335  auto __now = _Clock::now();
336  if (_Clock::is_steady)
337  {
338  if (__now < __atime)
339  sleep_for(__atime - __now);
340  return;
341  }
342  while (__now < __atime)
343  {
344  sleep_for(__atime - __now);
345  __now = _Clock::now();
346  }
347  }
348 
349  _GLIBCXX_END_NAMESPACE_VERSION
350  }
351 
352  // @} group threads
353 
354 } // namespace
355 
356 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
357 
358 #endif // C++11
359 
360 #endif // _GLIBCXX_THREAD
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:76
void yield() noexcept
yield
Definition: thread:298
constexpr enable_if< __is_duration< _ToDur >::value, _ToDur >::type duration_cast(const duration< _Rep, _Period > &__d)
duration_cast
Definition: chrono:194
void sleep_for(const chrono::duration< _Rep, _Period > &__rtime)
sleep_for
Definition: thread:311
thread::id get_id() noexcept
get_id
Definition: thread:283
thread::id
Definition: thread:76
20.7.1.2 unique_ptr for single objects.
Definition: unique_ptr.h:116
duration
Definition: chrono:64
native_handle_type native_handle()
Definition: thread:180
thread
Definition: thread:61
Primary class template hash.
Definition: system_error:134
void terminate() noexcept __attribute__((__noreturn__))
Template class basic_ostream.
Definition: iosfwd:86
void sleep_until(const chrono::time_point< _Clock, _Duration > &__atime)
sleep_until
Definition: thread:333