1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
|
// <stop_token> -*- C++ -*-
// Copyright (C) 2019-2020 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/stop_token
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_STOP_TOKEN
#define _GLIBCXX_STOP_TOKEN
#if __cplusplus > 201703L
#include <atomic>
#include <bits/std_mutex.h>
#include <ext/concurrence.h>
#include <bits/unique_ptr.h>
#include <bits/shared_ptr.h>
#ifdef _GLIBCXX_HAS_GTHREADS
# define __cpp_lib_jthread 201907L
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Tag type indicating a stop_source should have no shared-stop-state.
struct nostopstate_t { explicit nostopstate_t() = default; };
inline constexpr nostopstate_t nostopstate{};
/// Allow testing whether a stop request has been made on a `stop_source`.
class stop_token
{
public:
stop_token() noexcept = default;
stop_token(const stop_token& __other) noexcept = default;
stop_token(stop_token&& __other) noexcept = default;
~stop_token() = default;
stop_token&
operator=(const stop_token& __rhs) noexcept = default;
stop_token&
operator=(stop_token&& __rhs) noexcept = default;
[[nodiscard]]
bool
stop_possible() const noexcept
{
return static_cast<bool>(_M_state);
}
[[nodiscard]]
bool
stop_requested() const noexcept
{
return stop_possible() && _M_state->_M_stop_requested();
}
void
swap(stop_token& __rhs) noexcept
{ _M_state.swap(__rhs._M_state); }
[[nodiscard]]
friend bool
operator==(const stop_token& __a, const stop_token& __b)
{
return __a._M_state == __b._M_state;
}
[[nodiscard]]
friend bool
operator!=(const stop_token& __a, const stop_token& __b)
{
return __a._M_state != __b._M_state;
}
friend void
swap(stop_token& __lhs, stop_token& __rhs) noexcept
{ __lhs.swap(__rhs); }
private:
friend class stop_source;
template<typename _Callback>
friend class stop_callback;
struct _Stop_cb
{
void(*_M_callback)(_Stop_cb*);
_Stop_cb* _M_prev = nullptr;
_Stop_cb* _M_next = nullptr;
template<typename _Cb>
_Stop_cb(_Cb&& __cb)
: _M_callback(std::forward<_Cb>(__cb))
{ }
bool
_M_linked() const noexcept
{
return (_M_prev != nullptr)
|| (_M_next != nullptr);
}
static void
_S_execute(_Stop_cb* __cb) noexcept
{
__cb->_M_callback(__cb);
__cb->_M_prev = __cb->_M_next = nullptr;
}
};
struct _Stop_state_t
{
std::atomic<bool> _M_stopped{false};
_Stop_cb* _M_head = nullptr;
#ifdef _GLIBCXX_HAS_GTHREADS
std::mutex _M_mtx;
#endif
_Stop_state_t() = default;
bool
_M_stop_requested() noexcept
{
return _M_stopped;
}
bool
_M_request_stop()
{
bool __stopped = false;
if (_M_stopped.compare_exchange_strong(__stopped, true))
{
#ifdef _GLIBCXX_HAS_GTHREADS
std::lock_guard<std::mutex> __lck{_M_mtx};
#endif
while (_M_head)
{
auto __p = _M_head;
_M_head = _M_head->_M_next;
_Stop_cb::_S_execute(__p);
}
return true;
}
return false;
}
bool
_M_register_callback(_Stop_cb* __cb)
{
#ifdef _GLIBCXX_HAS_GTHREADS
std::lock_guard<std::mutex> __lck{_M_mtx};
#endif
if (_M_stopped)
return false;
__cb->_M_next = _M_head;
if (_M_head)
{
_M_head->_M_prev = __cb;
}
_M_head = __cb;
return true;
}
void
_M_remove_callback(_Stop_cb* __cb)
{
#ifdef _GLIBCXX_HAS_GTHREADS
std::lock_guard<std::mutex> __lck{_M_mtx};
#endif
if (__cb == _M_head)
{
_M_head = _M_head->_M_next;
if (_M_head)
{
_M_head->_M_prev = nullptr;
}
}
else if (!__cb->_M_linked())
{
return;
}
else
{
__cb->_M_prev->_M_next = __cb->_M_next;
if (__cb->_M_next)
{
__cb->_M_next->_M_prev = __cb->_M_prev;
}
}
}
};
using _Stop_state = std::shared_ptr<_Stop_state_t>;
_Stop_state _M_state;
explicit
stop_token(const _Stop_state& __state) noexcept
: _M_state{__state}
{ }
};
/// A type that allows a stop request to be made.
class stop_source
{
public:
stop_source()
: _M_state(std::make_shared<stop_token::_Stop_state_t>())
{ }
explicit stop_source(std::nostopstate_t) noexcept
{ }
stop_source(const stop_source& __other) noexcept
: _M_state(__other._M_state)
{ }
stop_source(stop_source&& __other) noexcept
: _M_state(std::move(__other._M_state))
{ }
stop_source&
operator=(const stop_source& __rhs) noexcept
{
if (_M_state != __rhs._M_state)
_M_state = __rhs._M_state;
return *this;
}
stop_source&
operator=(stop_source&& __rhs) noexcept
{
std::swap(_M_state, __rhs._M_state);
return *this;
}
[[nodiscard]]
bool
stop_possible() const noexcept
{
return static_cast<bool>(_M_state);
}
[[nodiscard]]
bool
stop_requested() const noexcept
{
return stop_possible() && _M_state->_M_stop_requested();
}
bool
request_stop() const noexcept
{
if (stop_possible())
return _M_state->_M_request_stop();
return false;
}
[[nodiscard]]
stop_token
get_token() const noexcept
{
return stop_token{_M_state};
}
void
swap(stop_source& __other) noexcept
{
_M_state.swap(__other._M_state);
}
[[nodiscard]]
friend bool
operator==(const stop_source& __a, const stop_source& __b) noexcept
{
return __a._M_state == __b._M_state;
}
[[nodiscard]]
friend bool
operator!=(const stop_source& __a, const stop_source& __b) noexcept
{
return __a._M_state != __b._M_state;
}
friend void
swap(stop_source& __lhs, stop_source& __rhs) noexcept
{
__lhs.swap(__rhs);
}
private:
stop_token::_Stop_state _M_state;
};
/// A wrapper for callbacks to be run when a stop request is made.
template<typename _Callback>
class [[nodiscard]] stop_callback
: private stop_token::_Stop_cb
{
public:
using callback_type = _Callback;
template<typename _Cb,
enable_if_t<is_constructible_v<_Callback, _Cb>, int> = 0>
explicit
stop_callback(const stop_token& __token, _Cb&& __cb)
noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
: _Stop_cb(&_S_execute), _M_cb(std::forward<_Cb>(__cb))
{
if (auto __state = __token._M_state)
{
if (__state->_M_stop_requested())
_S_execute(this); // ensures std::terminate on throw
else if (__state->_M_register_callback(this))
_M_state.swap(__state);
}
}
template<typename _Cb,
enable_if_t<is_constructible_v<_Callback, _Cb>, int> = 0>
explicit
stop_callback(stop_token&& __token, _Cb&& __cb)
noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
: _Stop_cb(&_S_execute), _M_cb(std::forward<_Cb>(__cb))
{
if (auto& __state = __token._M_state)
{
if (__state->_M_stop_requested())
_S_execute(this); // ensures std::terminate on throw
else if (__state->_M_register_callback(this))
_M_state.swap(__state);
}
}
~stop_callback()
{
if (_M_state)
{
_M_state->_M_remove_callback(this);
}
}
stop_callback(const stop_callback&) = delete;
stop_callback& operator=(const stop_callback&) = delete;
stop_callback(stop_callback&&) = delete;
stop_callback& operator=(stop_callback&&) = delete;
private:
_Callback _M_cb;
stop_token::_Stop_state _M_state = nullptr;
static void
_S_execute(_Stop_cb* __that) noexcept
{
static_cast<stop_callback*>(__that)->_M_cb();
}
};
template<typename _Callback>
stop_callback(stop_token, _Callback) -> stop_callback<_Callback>;
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // __cplusplus > 201703L
#endif // _GLIBCXX_STOP_TOKEN
|