1 // thread -*- 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
26 #define _GLIBCXX_THREAD_ABI_COMPAT 1
27 #include <memory> // include this first so <thread> can use shared_ptr
28 #include <thread>
29 #include <system_error>
30 #include <cerrno>
31 #include <cxxabi_forced.h>
32
33 #ifndef _GLIBCXX_USE_NANOSLEEP
34 # ifdef _GLIBCXX_HAVE_SLEEP
35 # include <unistd.h>
36 # elif defined(_GLIBCXX_HAVE_WIN32_SLEEP)
37 # include <windows.h>
38 # elif defined _GLIBCXX_NO_SLEEP && defined _GLIBCXX_HAS_GTHREADS
39 // We expect to be able to sleep for targets that support multiple threads:
40 # error "No sleep function known for this target"
41 # endif
42 #endif
43
44 #ifdef _GLIBCXX_HAS_GTHREADS
45
46 #if defined(_GLIBCXX_USE_GET_NPROCS)
47 # include <sys/sysinfo.h>
48 # define _GLIBCXX_NPROCS get_nprocs()
49 #elif defined(_GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP)
50 # define _GLIBCXX_NPROCS pthread_num_processors_np()
51 #elif defined(_GLIBCXX_USE_SYSCTL_HW_NCPU)
52 # include <stddef.h>
53 # include <sys/sysctl.h>
get_nprocs()54 static inline int get_nprocs()
55 {
56 int count;
57 size_t size = sizeof(count);
58 int mib[] = { CTL_HW, HW_NCPU };
59 if (!sysctl(mib, 2, &count, &size, NULL, 0))
60 return count;
61 return 0;
62 }
63 # define _GLIBCXX_NPROCS get_nprocs()
64 #elif defined(_GLIBCXX_USE_SC_NPROCESSORS_ONLN)
65 # include <unistd.h>
66 # define _GLIBCXX_NPROCS sysconf(_SC_NPROCESSORS_ONLN)
67 #elif defined(_GLIBCXX_USE_SC_NPROC_ONLN)
68 # include <unistd.h>
69 # define _GLIBCXX_NPROCS sysconf(_SC_NPROC_ONLN)
70 #else
71 # define _GLIBCXX_NPROCS 0
72 #endif
73
74 namespace std _GLIBCXX_VISIBILITY(default)
75 {
76 extern "C"
77 {
78 static void*
execute_native_thread_routine(void * __p)79 execute_native_thread_routine(void* __p)
80 {
81 thread::_State_ptr __t{ static_cast<thread::_State*>(__p) };
82 __t->_M_run();
83 return nullptr;
84 }
85
86 #if _GLIBCXX_THREAD_ABI_COMPAT
87 static void*
execute_native_thread_routine_compat(void * __p)88 execute_native_thread_routine_compat(void* __p)
89 {
90 thread::_Impl_base* __t = static_cast<thread::_Impl_base*>(__p);
91 thread::__shared_base_type __local;
92 // Now that a new thread has been created we can transfer ownership of
93 // the thread state to a local object, breaking the reference cycle
94 // created in thread::_M_start_thread.
95 __local.swap(__t->_M_this_ptr);
96 __t->_M_run();
97 return nullptr;
98 }
99 #endif
100 } // extern "C"
101
102 _GLIBCXX_BEGIN_NAMESPACE_VERSION
103
104 thread::_State::~_State() = default;
105
106 void
join()107 thread::join()
108 {
109 int __e = EINVAL;
110
111 if (_M_id != id())
112 __e = __gthread_join(_M_id._M_thread, 0);
113
114 if (__e)
115 __throw_system_error(__e);
116
117 _M_id = id();
118 }
119
120 void
detach()121 thread::detach()
122 {
123 int __e = EINVAL;
124
125 if (_M_id != id())
126 __e = __gthread_detach(_M_id._M_thread);
127
128 if (__e)
129 __throw_system_error(__e);
130
131 _M_id = id();
132 }
133
134 void
_M_start_thread(_State_ptr state,void (*)())135 thread::_M_start_thread(_State_ptr state, void (*)())
136 {
137 if (!__gthread_active_p())
138 {
139 #if __cpp_exceptions
140 throw system_error(make_error_code(errc::operation_not_permitted),
141 "Enable multithreading to use std::thread");
142 #else
143 __builtin_abort();
144 #endif
145 }
146
147 const int err = __gthread_create(&_M_id._M_thread,
148 &execute_native_thread_routine,
149 state.get());
150 if (err)
151 __throw_system_error(err);
152 state.release();
153 }
154
155 #if _GLIBCXX_THREAD_ABI_COMPAT
156 void
_M_start_thread(__shared_base_type __b)157 thread::_M_start_thread(__shared_base_type __b)
158 {
159 if (!__gthread_active_p())
160 #if __cpp_exceptions
161 throw system_error(make_error_code(errc::operation_not_permitted),
162 "Enable multithreading to use std::thread");
163 #else
164 __throw_system_error(int(errc::operation_not_permitted));
165 #endif
166
167 _M_start_thread(std::move(__b), nullptr);
168 }
169
170 void
_M_start_thread(__shared_base_type __b,void (*)())171 thread::_M_start_thread(__shared_base_type __b, void (*)())
172 {
173 auto ptr = __b.get();
174 // Create a reference cycle that will be broken in the new thread.
175 ptr->_M_this_ptr = std::move(__b);
176 int __e = __gthread_create(&_M_id._M_thread,
177 &execute_native_thread_routine_compat, ptr);
178 if (__e)
179 {
180 ptr->_M_this_ptr.reset(); // break reference cycle, destroying *ptr.
181 __throw_system_error(__e);
182 }
183 }
184 #endif
185
186 unsigned int
hardware_concurrency()187 thread::hardware_concurrency() noexcept
188 {
189 int __n = _GLIBCXX_NPROCS;
190 if (__n < 0)
191 __n = 0;
192 return __n;
193 }
194
195 _GLIBCXX_END_NAMESPACE_VERSION
196 } // namespace std
197
198 #endif // _GLIBCXX_HAS_GTHREADS
199
200 #ifndef _GLIBCXX_NO_SLEEP
201 namespace std _GLIBCXX_VISIBILITY(default)
202 {
203 _GLIBCXX_BEGIN_NAMESPACE_VERSION
204 namespace this_thread
205 {
206 void
__sleep_for(chrono::seconds __s,chrono::nanoseconds __ns)207 __sleep_for(chrono::seconds __s, chrono::nanoseconds __ns)
208 {
209 #ifdef _GLIBCXX_USE_NANOSLEEP
210 struct ::timespec __ts =
211 {
212 static_cast<std::time_t>(__s.count()),
213 static_cast<long>(__ns.count())
214 };
215 while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
216 { }
217 #elif defined(_GLIBCXX_HAVE_SLEEP)
218 const auto target = chrono::steady_clock::now() + __s + __ns;
219 while (true)
220 {
221 unsigned secs = __s.count();
222 if (__ns.count() > 0)
223 {
224 # ifdef _GLIBCXX_HAVE_USLEEP
225 long us = __ns.count() / 1000;
226 if (us == 0)
227 us = 1;
228 ::usleep(us);
229 # else
230 if (__ns.count() > 1000000 || secs == 0)
231 ++secs; // No sub-second sleep function, so round up.
232 # endif
233 }
234
235 if (secs > 0)
236 {
237 // Sleep in a loop to handle interruption by signals:
238 while ((secs = ::sleep(secs)))
239 { }
240 }
241 const auto now = chrono::steady_clock::now();
242 if (now >= target)
243 break;
244 __s = chrono::duration_cast<chrono::seconds>(target - now);
245 __ns = chrono::duration_cast<chrono::nanoseconds>(target - (now + __s));
246 }
247 #elif defined(_GLIBCXX_HAVE_WIN32_SLEEP)
248 unsigned long ms = __ns.count() / 1000000;
249 if (__ns.count() > 0 && ms == 0)
250 ms = 1;
251 ::Sleep(chrono::milliseconds(__s).count() + ms);
252 #endif
253 }
254 }
255 _GLIBCXX_END_NAMESPACE_VERSION
256 } // namespace std
257 #endif // ! NO_SLEEP
258