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 37 thread::~thread() 38 { 39 if (!__libcpp_thread_isnull(&__t_)) 40 terminate(); 41 } 42 43 void 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 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 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 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>& 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; 134 135 T* allocate(size_t __n) 136 {return static_cast<T*>(::operator new(__n * sizeof(T)));} 137 void deallocate(T* __p, size_t) {::operator delete(static_cast<void*>(__p));} 138 139 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: 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 }; 161 162 __thread_struct_imp::~__thread_struct_imp() 163 { 164 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); 165 i != e; ++i) 166 { 167 i->second->unlock(); 168 i->first->notify_all(); 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 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 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 192 193 __thread_struct::__thread_struct() 194 : __p_(new __thread_struct_imp) 195 { 196 } 197 198 __thread_struct::~__thread_struct() 199 { 200 delete __p_; 201 } 202 203 void 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 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