// <tr1 shared_ptr.h=""> -*- C++ -*-
// Copyright (C) 2007-2016 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: licenses="" www.gnu.org="">.
// shared_count.hpp
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
// shared_ptr.hpp
// Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
// Copyright (C) 2001, 2002, 2003 Peter Dimov
// weak_ptr.hpp
// Copyright (C) 2001, 2002, 2003 Peter Dimov
// enable_shared_from_this.hpp
// Copyright (C) 2002 Peter Dimov
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// https://www.boost.org/LICENSE_1_0.txt)
// GCC Note: based on version 1.32.0 of the Boost library.
/** @file tr1/shared_ptr.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{tr1/memory}
*/
#ifndef _TR1_SHARED_PTR_H
#define _TR1_SHARED_PTR_H 1
namespace std _GLIBCXX_VISIBILITY(default)
{
namespace tr1
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @brief Exception possibly thrown by @c shared_ptr.
* @ingroup exceptions
*/
class bad_weak_ptr : public std::exception
{
public:
virtual char const*
what() const throw()
{ return "tr1::bad_weak_ptr"; }
};
// Substitute for bad_weak_ptr object in the case of -fno-exceptions.
inline void
__throw_bad_weak_ptr()
{ _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }
using __gnu_cxx::_Lock_policy;
using __gnu_cxx::__default_lock_policy;
using __gnu_cxx::_S_single;
using __gnu_cxx::_S_mutex;
using __gnu_cxx::_S_atomic;
// Empty helper class except when the template argument is _S_mutex.
template<_Lock_policy _Lp>
class _Mutex_base
{
protected:
// The atomic policy uses fully-fenced builtins, single doesn't care.
enum { _S_need_barriers = 0 };
};
template<>
class _Mutex_base<_S_mutex>
: public __gnu_cxx::__mutex
{
protected:
// This policy is used when atomic builtins are not available.
// The replacement atomic operations might not have the necessary
// memory barriers.
enum { _S_need_barriers = 1 };
};
template<_Lock_policy _Lp = __default_lock_policy>
class _Sp_counted_base
: public _Mutex_base<_Lp>
{
public:
_Sp_counted_base()
: _M_use_count(1), _M_weak_count(1) { }
virtual
~_Sp_counted_base() // nothrow
{ }
// Called when _M_use_count drops to zero, to release the resources
// managed by *this.
virtual void
_M_dispose() = 0; // nothrow
// Called when _M_weak_count drops to zero.
virtual void
_M_destroy() // nothrow
{ delete this; }
virtual void*
_M_get_deleter(const std::type_info&) = 0;
void
_M_add_ref_copy()
{ __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
void
_M_add_ref_lock();
void
_M_release() // nothrow
{
// Be race-detector-friendly. For more info see bits/c++config.
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
{
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
_M_dispose();
// There must be a memory barrier between dispose() and destroy()
// to ensure that the effects of dispose() are observed in the
// thread that runs destroy().
// See https://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
if (_Mutex_base<_Lp>::_S_need_barriers)
{
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
// Be race-detector-friendly. For more info see bits/c++config.
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
-1) == 1)
{
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
_M_destroy();
}
}
}
void
_M_weak_add_ref() // nothrow
{ __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }
void
_M_weak_release() // nothrow
{
// Be race-detector-friendly. For more info see bits/c++config.
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
{
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
if (_Mutex_base<_Lp>::_S_need_barriers)
{
// See _M_release(),
// destroy() must observe results of dispose()
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
_M_destroy();
}
}
long
_M_get_use_count() const // nothrow
{
// No memory barrier is used here so there is no synchronization
// with other threads.
return const_cast<const volatile="">(_M_use_count);
}
private:
_Sp_counted_base(_Sp_counted_base const&);
_Sp_counted_base& operator=(_Sp_counted_base const&);
_Atomic_word _M_use_count; // #shared
_Atomic_word _M_weak_count; // #weak + (#shared != 0)
};
template<>
inline void
_Sp_counted_base<_S_single>::
_M_add_ref_lock()
{
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
{
_M_use_count = 0;
__throw_bad_weak_ptr();
}
}
template<>
inline void
_Sp_counted_base<_S_mutex>::
_M_add_ref_lock()
{
__gnu_cxx::__scoped_lock sentry(*this);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
{
_M_use_count = 0;
__throw_bad_weak_ptr();
}
}
template<>
inline void
_Sp_counted_base<_S_atomic>::
_M_add_ref_lock()
{
// Perform lock-free add-if-not-zero operation.
_Atomic_word __count = _M_use_count;
do
{
if (__count == 0)
__throw_bad_weak_ptr();
// Replace the current counter value with the old value + 1, as
// long as it's not changed meanwhile.
}
while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
true, __ATOMIC_ACQ_REL,
__ATOMIC_RELAXED));
}
template<typename _lock_policy="" _lp="" typename="">
class _Sp_counted_base_impl
: public _Sp_counted_base<_Lp>
{
public:
// Precondition: __d(__p) must not throw.
_Sp_counted_base_impl(_Ptr __p, _Deleter __d)
: _M_ptr(__p), _M_del(__d) { }
virtual void
_M_dispose() // nothrow
{ _M_del(_M_ptr); }
virtual void*
_M_get_deleter(const std::type_
