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 <__system_error/throw_system_error.h> 10 #include <__thread/poll_with_backoff.h> 11 #include <__thread/timed_backoff_policy.h> 12 #include <__utility/pair.h> 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 if (!__libcpp_thread_isnull(&__t_)) 39 terminate(); 40 } 41 42 void thread::join() { 43 int ec = EINVAL; 44 if (!__libcpp_thread_isnull(&__t_)) { 45 ec = __libcpp_thread_join(&__t_); 46 if (ec == 0) 47 __t_ = _LIBCPP_NULL_THREAD; 48 } 49 50 if (ec) 51 std::__throw_system_error(ec, "thread::join failed"); 52 } 53 54 void thread::detach() { 55 int ec = EINVAL; 56 if (!__libcpp_thread_isnull(&__t_)) { 57 ec = __libcpp_thread_detach(&__t_); 58 if (ec == 0) 59 __t_ = _LIBCPP_NULL_THREAD; 60 } 61 62 if (ec) 63 std::__throw_system_error(ec, "thread::detach failed"); 64 } 65 66 unsigned thread::hardware_concurrency() noexcept { 67 #if defined(_SC_NPROCESSORS_ONLN) 68 long result = sysconf(_SC_NPROCESSORS_ONLN); 69 // sysconf returns -1 if the name is invalid, the option does not exist or 70 // does not have a definite limit. 71 // if sysconf returns some other negative number, we have no idea 72 // what is going on. Default to something safe. 73 if (result < 0) 74 return 0; 75 return static_cast<unsigned>(result); 76 #elif defined(_LIBCPP_WIN32API) 77 SYSTEM_INFO info; 78 GetSystemInfo(&info); 79 return info.dwNumberOfProcessors; 80 #else // defined(CTL_HW) && defined(HW_NCPU) 81 // TODO: grovel through /proc or check cpuid on x86 and similar 82 // instructions on other architectures. 83 # if defined(_LIBCPP_WARNING) 84 _LIBCPP_WARNING("hardware_concurrency not yet implemented") 85 # else 86 # warning hardware_concurrency not yet implemented 87 # endif 88 return 0; // Means not computable [thread.thread.static] 89 #endif // defined(CTL_HW) && defined(HW_NCPU) 90 } 91 92 namespace this_thread { 93 94 void sleep_for(const chrono::nanoseconds& ns) { 95 if (ns > chrono::nanoseconds::zero()) { 96 __libcpp_thread_sleep_for(ns); 97 } 98 } 99 100 } // namespace this_thread 101 102 __thread_specific_ptr<__thread_struct>& __thread_local_data() { 103 // Even though __thread_specific_ptr's destructor doesn't actually destroy 104 // anything (see comments there), we can't call it at all because threads may 105 // outlive the static variable and calling its destructor means accessing an 106 // object outside of its lifetime, which is UB. 107 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)]; 108 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>(); 109 return *__p; 110 } 111 112 // __thread_struct_imp 113 114 template <class T> 115 class _LIBCPP_HIDDEN __hidden_allocator { 116 public: 117 typedef T value_type; 118 119 T* allocate(size_t __n) { return static_cast<T*>(::operator new(__n * sizeof(T))); } 120 void deallocate(T* __p, size_t) { ::operator delete(static_cast<void*>(__p)); } 121 122 size_t max_size() const { return size_t(~0) / sizeof(T); } 123 }; 124 125 class _LIBCPP_HIDDEN __thread_struct_imp { 126 typedef vector<__assoc_sub_state*, __hidden_allocator<__assoc_sub_state*> > _AsyncStates; 127 typedef vector<pair<condition_variable*, mutex*>, __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify; 128 129 _AsyncStates async_states_; 130 _Notify notify_; 131 132 __thread_struct_imp(const __thread_struct_imp&); 133 __thread_struct_imp& operator=(const __thread_struct_imp&); 134 135 public: 136 __thread_struct_imp() {} 137 ~__thread_struct_imp(); 138 139 void notify_all_at_thread_exit(condition_variable* cv, mutex* m); 140 void __make_ready_at_thread_exit(__assoc_sub_state* __s); 141 }; 142 143 __thread_struct_imp::~__thread_struct_imp() { 144 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); i != e; ++i) { 145 i->first->notify_all(); 146 i->second->unlock(); 147 } 148 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end(); i != e; ++i) { 149 (*i)->__make_ready(); 150 (*i)->__release_shared(); 151 } 152 } 153 154 void __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m) { 155 notify_.push_back(pair<condition_variable*, mutex*>(cv, m)); 156 } 157 158 void __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s) { 159 async_states_.push_back(__s); 160 __s->__add_shared(); 161 } 162 163 // __thread_struct 164 165 __thread_struct::__thread_struct() : __p_(new __thread_struct_imp) {} 166 167 __thread_struct::~__thread_struct() { delete __p_; } 168 169 void __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) { 170 __p_->notify_all_at_thread_exit(cv, m); 171 } 172 173 void __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) { __p_->__make_ready_at_thread_exit(__s); } 174 175 _LIBCPP_END_NAMESPACE_STD 176