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 <__thread/poll_with_backoff.h> 14 #include <__thread/timed_backoff_policy.h> 15 #include <exception> 16 #include <future> 17 #include <limits> 18 #include <thread> 19 #include <vector> 20 21 #if __has_include(<unistd.h>) 22 # include <unistd.h> // for sysconf 23 #endif 24 25 #if defined(__NetBSD__) 26 #pragma weak pthread_create // Do not create libpthread dependency 27 #endif 28 29 #if defined(_LIBCPP_WIN32API) 30 #include <windows.h> 31 #endif 32 33 #if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB) 34 #pragma comment(lib, "pthread") 35 #endif 36 37 _LIBCPP_BEGIN_NAMESPACE_STD 38 39 thread::~thread() 40 { 41 if (!__libcpp_thread_isnull(&__t_)) 42 terminate(); 43 } 44 45 void 46 thread::join() 47 { 48 int ec = EINVAL; 49 if (!__libcpp_thread_isnull(&__t_)) 50 { 51 ec = __libcpp_thread_join(&__t_); 52 if (ec == 0) 53 __t_ = _LIBCPP_NULL_THREAD; 54 } 55 56 if (ec) 57 __throw_system_error(ec, "thread::join failed"); 58 } 59 60 void 61 thread::detach() 62 { 63 int ec = EINVAL; 64 if (!__libcpp_thread_isnull(&__t_)) 65 { 66 ec = __libcpp_thread_detach(&__t_); 67 if (ec == 0) 68 __t_ = _LIBCPP_NULL_THREAD; 69 } 70 71 if (ec) 72 __throw_system_error(ec, "thread::detach failed"); 73 } 74 75 unsigned 76 thread::hardware_concurrency() noexcept 77 { 78 #if defined(_SC_NPROCESSORS_ONLN) 79 long result = sysconf(_SC_NPROCESSORS_ONLN); 80 // sysconf returns -1 if the name is invalid, the option does not exist or 81 // does not have a definite limit. 82 // if sysconf returns some other negative number, we have no idea 83 // what is going on. Default to something safe. 84 if (result < 0) 85 return 0; 86 return static_cast<unsigned>(result); 87 #elif defined(_LIBCPP_WIN32API) 88 SYSTEM_INFO info; 89 GetSystemInfo(&info); 90 return info.dwNumberOfProcessors; 91 #else // defined(CTL_HW) && defined(HW_NCPU) 92 // TODO: grovel through /proc or check cpuid on x86 and similar 93 // instructions on other architectures. 94 # if defined(_LIBCPP_WARNING) 95 _LIBCPP_WARNING("hardware_concurrency not yet implemented") 96 # else 97 # warning hardware_concurrency not yet implemented 98 # endif 99 return 0; // Means not computable [thread.thread.static] 100 #endif // defined(CTL_HW) && defined(HW_NCPU) 101 } 102 103 namespace this_thread 104 { 105 106 void 107 sleep_for(const chrono::nanoseconds& ns) 108 { 109 if (ns > chrono::nanoseconds::zero()) 110 { 111 __libcpp_thread_sleep_for(ns); 112 } 113 } 114 115 } // this_thread 116 117 __thread_specific_ptr<__thread_struct>& 118 __thread_local_data() 119 { 120 // Even though __thread_specific_ptr's destructor doesn't actually destroy 121 // anything (see comments there), we can't call it at all because threads may 122 // outlive the static variable and calling its destructor means accessing an 123 // object outside of its lifetime, which is UB. 124 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)]; 125 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>(); 126 return *__p; 127 } 128 129 // __thread_struct_imp 130 131 template <class T> 132 class _LIBCPP_HIDDEN __hidden_allocator 133 { 134 public: 135 typedef T value_type; 136 137 T* allocate(size_t __n) 138 {return static_cast<T*>(::operator new(__n * sizeof(T)));} 139 void deallocate(T* __p, size_t) {::operator delete(static_cast<void*>(__p));} 140 141 size_t max_size() const {return size_t(~0) / sizeof(T);} 142 }; 143 144 class _LIBCPP_HIDDEN __thread_struct_imp 145 { 146 typedef vector<__assoc_sub_state*, 147 __hidden_allocator<__assoc_sub_state*> > _AsyncStates; 148 typedef vector<pair<condition_variable*, mutex*>, 149 __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify; 150 151 _AsyncStates async_states_; 152 _Notify notify_; 153 154 __thread_struct_imp(const __thread_struct_imp&); 155 __thread_struct_imp& operator=(const __thread_struct_imp&); 156 public: 157 __thread_struct_imp() {} 158 ~__thread_struct_imp(); 159 160 void notify_all_at_thread_exit(condition_variable* cv, mutex* m); 161 void __make_ready_at_thread_exit(__assoc_sub_state* __s); 162 }; 163 164 __thread_struct_imp::~__thread_struct_imp() 165 { 166 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); 167 i != e; ++i) 168 { 169 i->first->notify_all(); 170 i->second->unlock(); 171 } 172 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end(); 173 i != e; ++i) 174 { 175 (*i)->__make_ready(); 176 (*i)->__release_shared(); 177 } 178 } 179 180 void 181 __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m) 182 { 183 notify_.push_back(pair<condition_variable*, mutex*>(cv, m)); 184 } 185 186 void 187 __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s) 188 { 189 async_states_.push_back(__s); 190 __s->__add_shared(); 191 } 192 193 // __thread_struct 194 195 __thread_struct::__thread_struct() 196 : __p_(new __thread_struct_imp) 197 { 198 } 199 200 __thread_struct::~__thread_struct() 201 { 202 delete __p_; 203 } 204 205 void 206 __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) 207 { 208 __p_->notify_all_at_thread_exit(cv, m); 209 } 210 211 void 212 __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) 213 { 214 __p_->__make_ready_at_thread_exit(__s); 215 } 216 217 _LIBCPP_END_NAMESPACE_STD 218 219 #endif // !_LIBCPP_HAS_NO_THREADS 220