1 // Support for pointer abstractions -*- C++ -*-
3 // Copyright (C) 2011-2015 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
27 namespace std _GLIBCXX_VISIBILITY(default)
29 _GLIBCXX_BEGIN_NAMESPACE_VERSION
31 bad_weak_ptr::~bad_weak_ptr() noexcept = default;
34 bad_weak_ptr::what() const noexcept
35 { return "bad_weak_ptr"; }
40 const unsigned char mask = 0xf;
41 const unsigned char invalid = mask + 1;
43 inline unsigned char key(const void* addr)
44 { return _Hash_impl::hash(addr) & mask; }
46 /* Returns different instances of __mutex depending on the passed address
47 * in order to limit contention.
50 get_mutex(unsigned char i)
52 static __gnu_cxx::__mutex m[mask + 1];
57 _Sp_locker::_Sp_locker(const void* p)
59 if (__gthread_active_p())
61 _M_key1 = _M_key2 = key(p);
62 get_mutex(_M_key1).lock();
65 _M_key1 = _M_key2 = invalid;
68 _Sp_locker::_Sp_locker(const void* p1, const void* p2)
70 if (__gthread_active_p())
74 if (_M_key2 < _M_key1)
75 get_mutex(_M_key2).lock();
76 get_mutex(_M_key1).lock();
77 if (_M_key2 > _M_key1)
78 get_mutex(_M_key2).lock();
81 _M_key1 = _M_key2 = invalid;
84 _Sp_locker::~_Sp_locker()
86 if (_M_key1 != invalid)
88 get_mutex(_M_key1).unlock();
89 if (_M_key2 != _M_key1)
90 get_mutex(_M_key2).unlock();
95 _GLIBCXX_END_NAMESPACE_VERSION