1 //===------------------------- thread.cpp----------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include <__config>
10
11 #ifndef _LIBCPP_HAS_NO_THREADS
12
13 #include <exception>
14 #include <future>
15 #include <limits>
16 #include <thread>
17 #include <vector>
18
19 #if __has_include(<unistd.h>)
20 # include <unistd.h> // for sysconf
21 #endif
22
23 #if defined(__NetBSD__)
24 #pragma weak pthread_create // Do not create libpthread dependency
25 #endif
26
27 #if defined(_LIBCPP_WIN32API)
28 #include <windows.h>
29 #endif
30
31 #if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
32 #pragma comment(lib, "pthread")
33 #endif
34
35 _LIBCPP_BEGIN_NAMESPACE_STD
36
~thread()37 thread::~thread()
38 {
39 if (!__libcpp_thread_isnull(&__t_))
40 terminate();
41 }
42
43 void
join()44 thread::join()
45 {
46 int ec = EINVAL;
47 if (!__libcpp_thread_isnull(&__t_))
48 {
49 ec = __libcpp_thread_join(&__t_);
50 if (ec == 0)
51 __t_ = _LIBCPP_NULL_THREAD;
52 }
53
54 if (ec)
55 __throw_system_error(ec, "thread::join failed");
56 }
57
58 void
detach()59 thread::detach()
60 {
61 int ec = EINVAL;
62 if (!__libcpp_thread_isnull(&__t_))
63 {
64 ec = __libcpp_thread_detach(&__t_);
65 if (ec == 0)
66 __t_ = _LIBCPP_NULL_THREAD;
67 }
68
69 if (ec)
70 __throw_system_error(ec, "thread::detach failed");
71 }
72
73 unsigned
hardware_concurrency()74 thread::hardware_concurrency() noexcept
75 {
76 #if defined(_SC_NPROCESSORS_ONLN)
77 long result = sysconf(_SC_NPROCESSORS_ONLN);
78 // sysconf returns -1 if the name is invalid, the option does not exist or
79 // does not have a definite limit.
80 // if sysconf returns some other negative number, we have no idea
81 // what is going on. Default to something safe.
82 if (result < 0)
83 return 0;
84 return static_cast<unsigned>(result);
85 #elif defined(_LIBCPP_WIN32API)
86 SYSTEM_INFO info;
87 GetSystemInfo(&info);
88 return info.dwNumberOfProcessors;
89 #else // defined(CTL_HW) && defined(HW_NCPU)
90 // TODO: grovel through /proc or check cpuid on x86 and similar
91 // instructions on other architectures.
92 # if defined(_LIBCPP_WARNING)
93 _LIBCPP_WARNING("hardware_concurrency not yet implemented")
94 # else
95 # warning hardware_concurrency not yet implemented
96 # endif
97 return 0; // Means not computable [thread.thread.static]
98 #endif // defined(CTL_HW) && defined(HW_NCPU)
99 }
100
101 namespace this_thread
102 {
103
104 void
sleep_for(const chrono::nanoseconds & ns)105 sleep_for(const chrono::nanoseconds& ns)
106 {
107 if (ns > chrono::nanoseconds::zero())
108 {
109 __libcpp_thread_sleep_for(ns);
110 }
111 }
112
113 } // this_thread
114
115 __thread_specific_ptr<__thread_struct>&
__thread_local_data()116 __thread_local_data()
117 {
118 // Even though __thread_specific_ptr's destructor doesn't actually destroy
119 // anything (see comments there), we can't call it at all because threads may
120 // outlive the static variable and calling its destructor means accessing an
121 // object outside of its lifetime, which is UB.
122 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)];
123 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>();
124 return *__p;
125 }
126
127 // __thread_struct_imp
128
129 template <class T>
130 class _LIBCPP_HIDDEN __hidden_allocator
131 {
132 public:
133 typedef T value_type;
134
allocate(size_t __n)135 T* allocate(size_t __n)
136 {return static_cast<T*>(::operator new(__n * sizeof(T)));}
deallocate(T * __p,size_t)137 void deallocate(T* __p, size_t) {::operator delete(static_cast<void*>(__p));}
138
max_size() const139 size_t max_size() const {return size_t(~0) / sizeof(T);}
140 };
141
142 class _LIBCPP_HIDDEN __thread_struct_imp
143 {
144 typedef vector<__assoc_sub_state*,
145 __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
146 typedef vector<pair<condition_variable*, mutex*>,
147 __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;
148
149 _AsyncStates async_states_;
150 _Notify notify_;
151
152 __thread_struct_imp(const __thread_struct_imp&);
153 __thread_struct_imp& operator=(const __thread_struct_imp&);
154 public:
__thread_struct_imp()155 __thread_struct_imp() {}
156 ~__thread_struct_imp();
157
158 void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
159 void __make_ready_at_thread_exit(__assoc_sub_state* __s);
160 };
161
~__thread_struct_imp()162 __thread_struct_imp::~__thread_struct_imp()
163 {
164 for (_Notify::iterator i = notify_.begin(), e = notify_.end();
165 i != e; ++i)
166 {
167 i->first->notify_all();
168 i->second->unlock();
169 }
170 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end();
171 i != e; ++i)
172 {
173 (*i)->__make_ready();
174 (*i)->__release_shared();
175 }
176 }
177
178 void
notify_all_at_thread_exit(condition_variable * cv,mutex * m)179 __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
180 {
181 notify_.push_back(pair<condition_variable*, mutex*>(cv, m));
182 }
183
184 void
__make_ready_at_thread_exit(__assoc_sub_state * __s)185 __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s)
186 {
187 async_states_.push_back(__s);
188 __s->__add_shared();
189 }
190
191 // __thread_struct
192
__thread_struct()193 __thread_struct::__thread_struct()
194 : __p_(new __thread_struct_imp)
195 {
196 }
197
~__thread_struct()198 __thread_struct::~__thread_struct()
199 {
200 delete __p_;
201 }
202
203 void
notify_all_at_thread_exit(condition_variable * cv,mutex * m)204 __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
205 {
206 __p_->notify_all_at_thread_exit(cv, m);
207 }
208
209 void
__make_ready_at_thread_exit(__assoc_sub_state * __s)210 __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s)
211 {
212 __p_->__make_ready_at_thread_exit(__s);
213 }
214
215 _LIBCPP_END_NAMESPACE_STD
216
217 #endif // !_LIBCPP_HAS_NO_THREADS
218