thread
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// <thread> -*- C++ -*-
// Copyright (C) 2008-2018 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/thread
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_THREAD
#define _GLIBCXX_THREAD 1
#pragma GCC system_header
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <chrono>
#include <memory>
#include <tuple>
#include <cerrno>
#include <bits/functexcept.h>
#include <bits/functional_hash.h>
#include <bits/invoke.h>
#include <bits/gthr.h>
#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @defgroup threads Threads
* @ingroup concurrency
*
* Classes for thread support.
* @{
*/
/// thread
class thread
{
public:
// Abstract base class for types that wrap arbitrary functors to be
// invoked in the new thread of execution.
struct _State
{
virtual ~_State();
virtual void _M_run() = 0;
};
using _State_ptr = unique_ptr<_State>;
typedef __gthread_t native_handle_type;
/// thread::id
class id
{
native_handle_type _M_thread;
public:
id() noexcept : _M_thread() { }
explicit
id(native_handle_type __id) : _M_thread(__id) { }
private:
friend class thread;
friend class hash<thread::id>;
friend bool
operator==(thread::id __x, thread::id __y) noexcept;
friend bool
operator<(thread::id __x, thread::id __y) noexcept;
template<class _CharT, class _Traits>
friend basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id);
};
private:
id _M_id;
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2097. packaged_task constructors should be constrained
template<typename _Tp>
using __not_same = __not_<is_same<
typename remove_cv<typename remove_reference<_Tp>::type>::type,
thread>>;
public:
thread() noexcept = default;
template<typename _Callable, typename... _Args,
typename = _Require<__not_same<_Callable>>>
explicit
thread(_Callable&& __f, _Args&&... __args)
{
static_assert( __is_invocable<typename decay<_Callable>::type,
typename decay<_Args>::type...>::value,
"std::thread arguments must be invocable after conversion to rvalues"
);
#ifdef GTHR_ACTIVE_PROXY
// Create a reference to pthread_create, not just the gthr weak symbol.
auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
#else
auto __depend = nullptr;
#endif
_M_start_thread(_S_make_state(
__make_invoker(std::forward<_Callable>(__f),
std::forward<_Args>(__args)...)),
__depend);
}
~thread()
{
if (joinable())
std::terminate();
}
thread(const thread&) = delete;
thread(thread&& __t) noexcept
{ swap(__t); }
thread& operator=(const thread&) = delete;
thread& operator=(thread&& __t) noexcept
{
if (joinable())
std::terminate();
swap(__t);
return *this;
}
void
swap(thread& __t) noexcept
{ std::swap(_M_id, __t._M_id); }
bool
joinable() const noexcept
{ return !(_M_id == id()); }
void
join();
void
detach();
thread::id
get_id() const noexcept
{ return _M_id; }
/** @pre thread is joinable
*/
native_handle_type
native_handle()
{ return _M_id._M_thread; }
// Returns a value that hints at the number of hardware thread contexts.
static unsigned int
hardware_concurrency() noexcept;
private:
template<typename _Callable>
struct _State_impl : public _State
{
_Callable _M_func;
_State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f))
{ }
void
_M_run() { _M_func(); }
};
void
_M_start_thread(_State_ptr, void (*)());
template<typename _Callable>
static _State_ptr
_S_make_state(_Callable&& __f)
{
using _Impl = _State_impl<_Callable>;
return _State_ptr{new _Impl{std::forward<_Callable>(__f)}};
}
#if _GLIBCXX_THREAD_ABI_COMPAT
public:
struct _Impl_base;
typedef shared_ptr<_Impl_base> __shared_base_type;
struct _Impl_base
{
__shared_base_type _M_this_ptr;
virtual ~_Impl_base() = default;
virtual void _M_run() = 0;
};
private:
void
_M_start_thread(__shared_base_type, void (*)());
void
_M_start_thread(__shared_base_type);
#endif
private:
// A call wrapper that does INVOKE(forwarded tuple elements...)
template<typename _Tuple>
struct _Invoker
{
_Tuple _M_t;
template<size_t _Index>
static __tuple_element_t<_Index, _Tuple>&&
_S_declval();
template<size_t... _Ind>
auto
_M_invoke(_Index_tuple<_Ind...>)
noexcept(noexcept(std::__invoke(_S_declval<_Ind>()...)))
-> decltype(std::__invoke(_S_declval<_Ind>()...))
{ return std::__invoke(std::get<_Ind>(std::move(_M_t))...); }
using _Indices
= typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type;
auto
operator()()
noexcept(noexcept(std::declval<_Invoker&>()._M_invoke(_Indices())))
-> decltype(std::declval<_Invoker&>()._M_invoke(_Indices()))
{ return _M_invoke(_Indices()); }
};
template<typename... _Tp>
using __decayed_tuple = tuple<typename std::decay<_Tp>::type...>;
public:
// Returns a call wrapper that stores
// tuple{DECAY_COPY(__callable), DECAY_COPY(__args)...}.
template<typename _Callable, typename... _Args>
static _Invoker<__decayed_tuple<_Callable, _Args...>>
__make_invoker(_Callable&& __callable, _Args&&... __args)
{
return { __decayed_tuple<_Callable, _Args...>{
std::forward<_Callable>(__callable), std::forward<_Args>(__args)...
} };
}
};
inline void
swap(thread& __x, thread& __y) noexcept
{ __x.swap(__y); }
inline bool
operator==(thread::id __x, thread::id __y) noexcept
{
// pthread_equal is undefined if either thread ID is not valid, so we
// can't safely use __gthread_equal on default-constructed values (nor
// the non-zero value returned by this_thread::get_id() for
// single-threaded programs using GNU libc). Assume EqualityComparable.
return __x._M_thread == __y._M_thread;
}
inline bool
operator!=(thread::id __x, thread::id __y) noexcept
{ return !(__x == __y); }
inline bool
operator<(thread::id __x, thread::id __y) noexcept
{
// Pthreads doesn't define any way to do this, so we just have to
// assume native_handle_type is LessThanComparable.
return __x._M_thread < __y._M_thread;
}
inline bool
operator<=(thread::id __x, thread::id __y) noexcept
{ return !(__y < __x); }
inline bool
operator>(thread::id __x, thread::id __y) noexcept
{ return __y < __x; }
inline bool
operator>=(thread::id __x, thread::id __y) noexcept
{ return !(__x < __y); }
// DR 889.
/// std::hash specialization for thread::id.
template<>
struct hash<thread::id>
: public __hash_base<size_t, thread::id>
{
size_t
operator()(const thread::id& __id) const noexcept
{ return std::_Hash_impl::hash(__id._M_thread); }
};
template<class _CharT, class _Traits>
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
{
if (__id == thread::id())
return __out << "thread::id of a non-executing thread";
else
return __out << __id._M_thread;
}
/** @namespace std::this_thread
* @brief ISO C++ 2011 entities sub-namespace for thread.
* 30.3.2 Namespace this_thread.
*/
namespace this_thread
{
/// get_id
inline thread::id
get_id() noexcept
{
#ifdef __GLIBC__
// For the GNU C library pthread_self() is usable without linking to
// libpthread.so but returns 0, so we cannot use it in single-threaded
// programs, because this_thread::get_id() != thread::id{} must be true.
// We know that pthread_t is an integral type in the GNU C library.
if (!__gthread_active_p())
return thread::id(1);
#endif
return thread::id(__gthread_self());
}
/// yield
inline void
yield() noexcept
{
#ifdef _GLIBCXX_USE_SCHED_YIELD
__gthread_yield();
#endif
}
void
__sleep_for(chrono::seconds, chrono::nanoseconds);
/// sleep_for
template<typename _Rep, typename _Period>
inline void
sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
{
if (__rtime <= __rtime.zero())
return;
auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
#ifdef _GLIBCXX_USE_NANOSLEEP
__gthread_time_t __ts =
{
static_cast<std::time_t>(__s.count()),
static_cast<long>(__ns.count())
};
while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
{ }
#else
__sleep_for(__s, __ns);
#endif
}
/// sleep_until
template<typename _Clock, typename _Duration>
inline void
sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
{
auto __now = _Clock::now();
if (_Clock::is_steady)
{
if (__now < __atime)
sleep_for(__atime - __now);
return;
}
while (__now < __atime)
{
sleep_for(__atime - __now);
__now = _Clock::now();
}
}
}
// @} group threads
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
#endif // C++11
#endif // _GLIBCXX_THREAD