wut/libraries/wutstdc++/shared_ptr.cc

89 lines
2.5 KiB
C++

// Support for pointer abstractions -*- C++ -*-
// Copyright (C) 2011-2018 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/>.
#include <memory>
namespace __gnu_internal _GLIBCXX_VISIBILITY(hidden)
{
const unsigned char mask = 0xf;
const unsigned char invalid = mask + 1;
/* Returns different instances of __mutex depending on the passed index
* in order to limit contention.
*/
__gnu_cxx::__mutex& get_mutex(unsigned char i);
}
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#ifdef __GTHREADS
namespace
{
inline unsigned char key(const void* addr)
{ return _Hash_impl::hash(addr) & __gnu_internal::mask; }
}
_Sp_locker::_Sp_locker(const void* p) noexcept
{
if (__gthread_active_p())
{
_M_key1 = _M_key2 = key(p);
__gnu_internal::get_mutex(_M_key1).lock();
}
else
_M_key1 = _M_key2 = __gnu_internal::invalid;
}
_Sp_locker::_Sp_locker(const void* p1, const void* p2) noexcept
{
if (__gthread_active_p())
{
_M_key1 = key(p1);
_M_key2 = key(p2);
if (_M_key2 < _M_key1)
__gnu_internal::get_mutex(_M_key2).lock();
__gnu_internal::get_mutex(_M_key1).lock();
if (_M_key2 > _M_key1)
__gnu_internal::get_mutex(_M_key2).lock();
}
else
_M_key1 = _M_key2 = __gnu_internal::invalid;
}
_Sp_locker::~_Sp_locker()
{
if (_M_key1 != __gnu_internal::invalid)
{
__gnu_internal::get_mutex(_M_key1).unlock();
if (_M_key2 != _M_key1)
__gnu_internal::get_mutex(_M_key2).unlock();
}
}
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace