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 if (!__libcpp_thread_isnull(&__t_)) 37 terminate(); 38 } 39 40 void thread::join() { 41 int ec = EINVAL; 42 if (!__libcpp_thread_isnull(&__t_)) { 43 ec = __libcpp_thread_join(&__t_); 44 if (ec == 0) 45 __t_ = _LIBCPP_NULL_THREAD; 46 } 47 48 if (ec) 49 __throw_system_error(ec, "thread::join failed"); 50 } 51 52 void thread::detach() { 53 int ec = EINVAL; 54 if (!__libcpp_thread_isnull(&__t_)) { 55 ec = __libcpp_thread_detach(&__t_); 56 if (ec == 0) 57 __t_ = _LIBCPP_NULL_THREAD; 58 } 59 60 if (ec) 61 __throw_system_error(ec, "thread::detach failed"); 62 } 63 64 unsigned thread::hardware_concurrency() noexcept { 65 #if defined(_SC_NPROCESSORS_ONLN) 66 long result = sysconf(_SC_NPROCESSORS_ONLN); 67 // sysconf returns -1 if the name is invalid, the option does not exist or 68 // does not have a definite limit. 69 // if sysconf returns some other negative number, we have no idea 70 // what is going on. Default to something safe. 71 if (result < 0) 72 return 0; 73 return static_cast<unsigned>(result); 74 #elif defined(_LIBCPP_WIN32API) 75 SYSTEM_INFO info; 76 GetSystemInfo(&info); 77 return info.dwNumberOfProcessors; 78 #else // defined(CTL_HW) && defined(HW_NCPU) 79 // TODO: grovel through /proc or check cpuid on x86 and similar 80 // instructions on other architectures. 81 # if defined(_LIBCPP_WARNING) 82 _LIBCPP_WARNING("hardware_concurrency not yet implemented") 83 # else 84 # warning hardware_concurrency not yet implemented 85 # endif 86 return 0; // Means not computable [thread.thread.static] 87 #endif // defined(CTL_HW) && defined(HW_NCPU) 88 } 89 90 namespace this_thread { 91 92 void sleep_for(const chrono::nanoseconds& ns) { 93 if (ns > chrono::nanoseconds::zero()) { 94 __libcpp_thread_sleep_for(ns); 95 } 96 } 97 98 } // namespace this_thread 99 100 __thread_specific_ptr<__thread_struct>& __thread_local_data() { 101 // Even though __thread_specific_ptr's destructor doesn't actually destroy 102 // anything (see comments there), we can't call it at all because threads may 103 // outlive the static variable and calling its destructor means accessing an 104 // object outside of its lifetime, which is UB. 105 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)]; 106 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>(); 107 return *__p; 108 } 109 110 // __thread_struct_imp 111 112 template <class T> 113 class _LIBCPP_HIDDEN __hidden_allocator { 114 public: 115 typedef T value_type; 116 117 T* allocate(size_t __n) { return static_cast<T*>(::operator new(__n * sizeof(T))); } 118 void deallocate(T* __p, size_t) { ::operator delete(static_cast<void*>(__p)); } 119 120 size_t max_size() const { return size_t(~0) / sizeof(T); } 121 }; 122 123 class _LIBCPP_HIDDEN __thread_struct_imp { 124 typedef vector<__assoc_sub_state*, __hidden_allocator<__assoc_sub_state*> > _AsyncStates; 125 typedef vector<pair<condition_variable*, mutex*>, __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify; 126 127 _AsyncStates async_states_; 128 _Notify notify_; 129 130 __thread_struct_imp(const __thread_struct_imp&); 131 __thread_struct_imp& operator=(const __thread_struct_imp&); 132 133 public: 134 __thread_struct_imp() {} 135 ~__thread_struct_imp(); 136 137 void notify_all_at_thread_exit(condition_variable* cv, mutex* m); 138 void __make_ready_at_thread_exit(__assoc_sub_state* __s); 139 }; 140 141 __thread_struct_imp::~__thread_struct_imp() { 142 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); i != e; ++i) { 143 i->first->notify_all(); 144 i->second->unlock(); 145 } 146 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end(); i != e; ++i) { 147 (*i)->__make_ready(); 148 (*i)->__release_shared(); 149 } 150 } 151 152 void __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m) { 153 notify_.push_back(pair<condition_variable*, mutex*>(cv, m)); 154 } 155 156 void __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s) { 157 async_states_.push_back(__s); 158 __s->__add_shared(); 159 } 160 161 // __thread_struct 162 163 __thread_struct::__thread_struct() : __p_(new __thread_struct_imp) {} 164 165 __thread_struct::~__thread_struct() { delete __p_; } 166 167 void __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) { 168 __p_->notify_all_at_thread_exit(cv, m); 169 } 170 171 void __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) { __p_->__make_ready_at_thread_exit(__s); } 172 173 _LIBCPP_END_NAMESPACE_STD 174