174 lines · cpp
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-exception6//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 sysconf21#endif22 23#if defined(__NetBSD__)24# pragma weak pthread_create // Do not create libpthread dependency25#endif26 27#if defined(_LIBCPP_WIN32API)28# include <windows.h>29#endif30 31#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)32# pragma comment(lib, "pthread")33#endif34 35_LIBCPP_BEGIN_NAMESPACE_STD36 37thread::~thread() {38 if (!__libcpp_thread_isnull(&__t_))39 terminate();40}41 42void 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 54void 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 66unsigned 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 or70 // does not have a definite limit.71 // if sysconf returns some other negative number, we have no idea72 // 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 return static_cast<unsigned>(GetActiveProcessorCount(ALL_PROCESSOR_GROUPS));78#else // defined(CTL_HW) && defined(HW_NCPU)79 // TODO: grovel through /proc or check cpuid on x86 and similar80 // instructions on other architectures.81# if defined(_LIBCPP_WARNING)82 _LIBCPP_WARNING("hardware_concurrency not yet implemented")83# else84# warning hardware_concurrency not yet implemented85# endif86 return 0; // Means not computable [thread.thread.static]87#endif // defined(CTL_HW) && defined(HW_NCPU)88}89 90namespace this_thread {91 92void sleep_for(const chrono::nanoseconds& ns) {93 if (ns > chrono::nanoseconds::zero()) {94 __libcpp_thread_sleep_for(ns);95 }96}97 98} // namespace this_thread99 100__thread_specific_ptr<__thread_struct>& __thread_local_data() {101 // Even though __thread_specific_ptr's destructor doesn't actually destroy102 // anything (see comments there), we can't call it at all because threads may103 // outlive the static variable and calling its destructor means accessing an104 // 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_imp111 112template <class T>113class _LIBCPP_HIDDEN __hidden_allocator {114public: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 123class _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 133public: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 152void __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 156void __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_struct162 163__thread_struct::__thread_struct() : __p_(new __thread_struct_imp) {}164 165__thread_struct::~__thread_struct() { delete __p_; }166 167void __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) {168 __p_->notify_all_at_thread_exit(cv, m);169}170 171void __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) { __p_->__make_ready_at_thread_exit(__s); }172 173_LIBCPP_END_NAMESPACE_STD174