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 <__thread/poll_with_backoff.h> 10 #include <__thread/timed_backoff_policy.h> 11 #include <exception> 12 #include <future> 13 #include <limits> 14 #include <thread> 15 #include <vector> 16 17 #if __has_include(<unistd.h>) 18 # include <unistd.h> // for sysconf 19 #endif 20 21 #if defined(__NetBSD__) 22 #pragma weak pthread_create // Do not create libpthread dependency 23 #endif 24 25 #if defined(_LIBCPP_WIN32API) 26 #include <windows.h> 27 #endif 28 29 #if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB) 30 #pragma comment(lib, "pthread") 31 #endif 32 33 _LIBCPP_BEGIN_NAMESPACE_STD 34 35 thread::~thread() 36 { 37 if (!__libcpp_thread_isnull(&__t_)) 38 terminate(); 39 } 40 41 void 42 thread::join() 43 { 44 int ec = EINVAL; 45 if (!__libcpp_thread_isnull(&__t_)) 46 { 47 ec = __libcpp_thread_join(&__t_); 48 if (ec == 0) 49 __t_ = _LIBCPP_NULL_THREAD; 50 } 51 52 if (ec) 53 __throw_system_error(ec, "thread::join failed"); 54 } 55 56 void 57 thread::detach() 58 { 59 int ec = EINVAL; 60 if (!__libcpp_thread_isnull(&__t_)) 61 { 62 ec = __libcpp_thread_detach(&__t_); 63 if (ec == 0) 64 __t_ = _LIBCPP_NULL_THREAD; 65 } 66 67 if (ec) 68 __throw_system_error(ec, "thread::detach failed"); 69 } 70 71 unsigned 72 thread::hardware_concurrency() noexcept 73 { 74 #if defined(_SC_NPROCESSORS_ONLN) 75 long result = sysconf(_SC_NPROCESSORS_ONLN); 76 // sysconf returns -1 if the name is invalid, the option does not exist or 77 // does not have a definite limit. 78 // if sysconf returns some other negative number, we have no idea 79 // what is going on. Default to something safe. 80 if (result < 0) 81 return 0; 82 return static_cast<unsigned>(result); 83 #elif defined(_LIBCPP_WIN32API) 84 SYSTEM_INFO info; 85 GetSystemInfo(&info); 86 return info.dwNumberOfProcessors; 87 #else // defined(CTL_HW) && defined(HW_NCPU) 88 // TODO: grovel through /proc or check cpuid on x86 and similar 89 // instructions on other architectures. 90 # if defined(_LIBCPP_WARNING) 91 _LIBCPP_WARNING("hardware_concurrency not yet implemented") 92 # else 93 # warning hardware_concurrency not yet implemented 94 # endif 95 return 0; // Means not computable [thread.thread.static] 96 #endif // defined(CTL_HW) && defined(HW_NCPU) 97 } 98 99 namespace this_thread 100 { 101 102 void 103 sleep_for(const chrono::nanoseconds& ns) 104 { 105 if (ns > chrono::nanoseconds::zero()) 106 { 107 __libcpp_thread_sleep_for(ns); 108 } 109 } 110 111 } // this_thread 112 113 __thread_specific_ptr<__thread_struct>& 114 __thread_local_data() 115 { 116 // Even though __thread_specific_ptr's destructor doesn't actually destroy 117 // anything (see comments there), we can't call it at all because threads may 118 // outlive the static variable and calling its destructor means accessing an 119 // object outside of its lifetime, which is UB. 120 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)]; 121 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>(); 122 return *__p; 123 } 124 125 // __thread_struct_imp 126 127 template <class T> 128 class _LIBCPP_HIDDEN __hidden_allocator 129 { 130 public: 131 typedef T value_type; 132 133 T* allocate(size_t __n) 134 {return static_cast<T*>(::operator new(__n * sizeof(T)));} 135 void deallocate(T* __p, size_t) {::operator delete(static_cast<void*>(__p));} 136 137 size_t max_size() const {return size_t(~0) / sizeof(T);} 138 }; 139 140 class _LIBCPP_HIDDEN __thread_struct_imp 141 { 142 typedef vector<__assoc_sub_state*, 143 __hidden_allocator<__assoc_sub_state*> > _AsyncStates; 144 typedef vector<pair<condition_variable*, mutex*>, 145 __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify; 146 147 _AsyncStates async_states_; 148 _Notify notify_; 149 150 __thread_struct_imp(const __thread_struct_imp&); 151 __thread_struct_imp& operator=(const __thread_struct_imp&); 152 public: 153 __thread_struct_imp() {} 154 ~__thread_struct_imp(); 155 156 void notify_all_at_thread_exit(condition_variable* cv, mutex* m); 157 void __make_ready_at_thread_exit(__assoc_sub_state* __s); 158 }; 159 160 __thread_struct_imp::~__thread_struct_imp() 161 { 162 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); 163 i != e; ++i) 164 { 165 i->first->notify_all(); 166 i->second->unlock(); 167 } 168 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end(); 169 i != e; ++i) 170 { 171 (*i)->__make_ready(); 172 (*i)->__release_shared(); 173 } 174 } 175 176 void 177 __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m) 178 { 179 notify_.push_back(pair<condition_variable*, mutex*>(cv, m)); 180 } 181 182 void 183 __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s) 184 { 185 async_states_.push_back(__s); 186 __s->__add_shared(); 187 } 188 189 // __thread_struct 190 191 __thread_struct::__thread_struct() 192 : __p_(new __thread_struct_imp) 193 { 194 } 195 196 __thread_struct::~__thread_struct() 197 { 198 delete __p_; 199 } 200 201 void 202 __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) 203 { 204 __p_->notify_all_at_thread_exit(cv, m); 205 } 206 207 void 208 __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) 209 { 210 __p_->__make_ready_at_thread_exit(__s); 211 } 212 213 _LIBCPP_END_NAMESPACE_STD 214