xref: /freebsd-src/contrib/llvm-project/libcxx/include/__thread/thread.h (revision 5f757f3ff9144b609b3c433dfd370cc6bdc191ad)

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___THREAD_THREAD_H
#define _LIBCPP___THREAD_THREAD_H

#include <__condition_variable/condition_variable.h>
#include <__config>
#include <__exception/terminate.h>
#include <__functional/hash.h>
#include <__functional/unary_function.h>
#include <__memory/unique_ptr.h>
#include <__mutex/mutex.h>
#include <__system_error/system_error.h>
#include <__thread/id.h>
#include <__threading_support>
#include <__utility/forward.h>
#include <tuple>

#ifndef _LIBCPP_HAS_NO_LOCALIZATION
#  include <locale>
#  include <sstream>
#endif

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp> class __thread_specific_ptr;
class _LIBCPP_EXPORTED_FROM_ABI __thread_struct;
class _LIBCPP_HIDDEN __thread_struct_imp;
class __assoc_sub_state;

_LIBCPP_EXPORTED_FROM_ABI __thread_specific_ptr<__thread_struct>& __thread_local_data();

class _LIBCPP_EXPORTED_FROM_ABI __thread_struct
{
    __thread_struct_imp* __p_;

    __thread_struct(const __thread_struct&);
    __thread_struct& operator=(const __thread_struct&);
public:
    __thread_struct();
    ~__thread_struct();

    void notify_all_at_thread_exit(condition_variable*, mutex*);
    void __make_ready_at_thread_exit(__assoc_sub_state*);
};

template <class _Tp>
class __thread_specific_ptr
{
    __libcpp_tls_key __key_;

     // Only __thread_local_data() may construct a __thread_specific_ptr
     // and only with _Tp == __thread_struct.
    static_assert((is_same<_Tp, __thread_struct>::value), "");
    __thread_specific_ptr();
    friend _LIBCPP_EXPORTED_FROM_ABI __thread_specific_ptr<__thread_struct>& __thread_local_data();

    __thread_specific_ptr(const __thread_specific_ptr&);
    __thread_specific_ptr& operator=(const __thread_specific_ptr&);

    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);

public:
    typedef _Tp* pointer;

    ~__thread_specific_ptr();

    _LIBCPP_HIDE_FROM_ABI
    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
    _LIBCPP_HIDE_FROM_ABI
    pointer operator*() const {return *get();}
    _LIBCPP_HIDE_FROM_ABI
    pointer operator->() const {return get();}
    void set_pointer(pointer __p);
};

template <class _Tp>
void _LIBCPP_TLS_DESTRUCTOR_CC
__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
{
    delete static_cast<pointer>(__p);
}

template <class _Tp>
__thread_specific_ptr<_Tp>::__thread_specific_ptr()
{
  int __ec =
      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
  if (__ec)
    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
}

template <class _Tp>
__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
{
    // __thread_specific_ptr is only created with a static storage duration
    // so this destructor is only invoked during program termination. Invoking
    // pthread_key_delete(__key_) may prevent other threads from deleting their
    // thread local data. For this reason we leak the key.
}

template <class _Tp>
void
__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
{
    _LIBCPP_ASSERT_UNCATEGORIZED(get() == nullptr,
                   "Attempting to overwrite thread local data");
    std::__libcpp_tls_set(__key_, __p);
}

template<>
struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
    : public __unary_function<__thread_id, size_t>
{
    _LIBCPP_HIDE_FROM_ABI
    size_t operator()(__thread_id __v) const _NOEXCEPT
    {
        return hash<__libcpp_thread_id>()(__v.__id_);
    }
};

#ifndef _LIBCPP_HAS_NO_LOCALIZATION
template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id) {
    // [thread.thread.id]/9
    //   Effects: Inserts the text representation for charT of id into out.
    //
    // [thread.thread.id]/2
    //   The text representation for the character type charT of an
    //   object of type thread::id is an unspecified sequence of charT
    //   such that, for two objects of type thread::id x and y, if
    //   x == y is true, the thread::id objects have the same text
    //   representation, and if x != y is true, the thread::id objects
    //   have distinct text representations.
    //
    // Since various flags in the output stream can affect how the
    // thread id is represented (e.g. numpunct or showbase), we
    // use a temporary stream instead and just output the thread
    // id representation as a string.

    basic_ostringstream<_CharT, _Traits> __sstr;
    __sstr.imbue(locale::classic());
    __sstr << __id.__id_;
    return __os << __sstr.str();
}
#endif // _LIBCPP_HAS_NO_LOCALIZATION

class _LIBCPP_EXPORTED_FROM_ABI thread
{
    __libcpp_thread_t __t_;

    thread(const thread&);
    thread& operator=(const thread&);
public:
    typedef __thread_id id;
    typedef __libcpp_thread_t native_handle_type;

    _LIBCPP_HIDE_FROM_ABI
    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
#ifndef _LIBCPP_CXX03_LANG
    template <class _Fp, class ..._Args,
              class = __enable_if_t<!is_same<__remove_cvref_t<_Fp>, thread>::value> >
        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
        explicit thread(_Fp&& __f, _Args&&... __args);
#else  // _LIBCPP_CXX03_LANG
    template <class _Fp>
    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
    explicit thread(_Fp __f);
#endif
    ~thread();

    _LIBCPP_HIDE_FROM_ABI
    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {
        __t.__t_ = _LIBCPP_NULL_THREAD;
    }

    _LIBCPP_HIDE_FROM_ABI
    thread& operator=(thread&& __t) _NOEXCEPT {
        if (!__libcpp_thread_isnull(&__t_))
            terminate();
        __t_ = __t.__t_;
        __t.__t_ = _LIBCPP_NULL_THREAD;
        return *this;
    }

    _LIBCPP_HIDE_FROM_ABI
    void swap(thread& __t) _NOEXCEPT {std::swap(__t_, __t.__t_);}

    _LIBCPP_HIDE_FROM_ABI
    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
    void join();
    void detach();
    _LIBCPP_HIDE_FROM_ABI
    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
    _LIBCPP_HIDE_FROM_ABI
    native_handle_type native_handle() _NOEXCEPT {return __t_;}

    static unsigned hardware_concurrency() _NOEXCEPT;
};

#ifndef _LIBCPP_CXX03_LANG

template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
inline _LIBCPP_HIDE_FROM_ABI
void
__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
{
    std::__invoke(std::move(std::get<1>(__t)), std::move(std::get<_Indices>(__t))...);
}

template <class _Fp>
_LIBCPP_HIDE_FROM_ABI
void* __thread_proxy(void* __vp)
{
    // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
    __thread_local_data().set_pointer(std::get<0>(*__p.get()).release());
    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
    std::__thread_execute(*__p.get(), _Index());
    return nullptr;
}

template <class _Fp, class ..._Args,
          class
         >
thread::thread(_Fp&& __f, _Args&&... __args)
{
    typedef unique_ptr<__thread_struct> _TSPtr;
    _TSPtr __tsp(new __thread_struct);
    typedef tuple<_TSPtr, __decay_t<_Fp>, __decay_t<_Args>...> _Gp;
    unique_ptr<_Gp> __p(
            new _Gp(std::move(__tsp),
                    std::forward<_Fp>(__f),
                    std::forward<_Args>(__args)...));
    int __ec = std::__libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
    if (__ec == 0)
        __p.release();
    else
        __throw_system_error(__ec, "thread constructor failed");
}

#else  // _LIBCPP_CXX03_LANG

template <class _Fp>
struct __thread_invoke_pair {
    // This type is used to pass memory for thread local storage and a functor
    // to a newly created thread because std::pair doesn't work with
    // std::unique_ptr in C++03.
    _LIBCPP_HIDE_FROM_ABI __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
    unique_ptr<__thread_struct> __tsp_;
    _Fp __fn_;
};

template <class _Fp>
_LIBCPP_HIDE_FROM_ABI void* __thread_proxy_cxx03(void* __vp)
{
    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
    __thread_local_data().set_pointer(__p->__tsp_.release());
    (__p->__fn_)();
    return nullptr;
}

template <class _Fp>
thread::thread(_Fp __f)
{

    typedef __thread_invoke_pair<_Fp> _InvokePair;
    typedef unique_ptr<_InvokePair> _PairPtr;
    _PairPtr __pp(new _InvokePair(__f));
    int __ec = std::__libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
    if (__ec == 0)
        __pp.release();
    else
        __throw_system_error(__ec, "thread constructor failed");
}

#endif // _LIBCPP_CXX03_LANG

inline _LIBCPP_HIDE_FROM_ABI
void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___THREAD_THREAD_H