1 // Support for pointer abstractions -*- C++ -*- 2 3 // Copyright (C) 2011-2015 Free Software Foundation, Inc. 4 // 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) 9 // any later version. 10 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. 15 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. 19 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/>. 24 25 #include <memory> 26 27 namespace std _GLIBCXX_VISIBILITY(default) 28 { 29 _GLIBCXX_BEGIN_NAMESPACE_VERSION 30 31 bad_weak_ptr::~bad_weak_ptr() noexcept = default; 32 33 char const* what() const34 bad_weak_ptr::what() const noexcept 35 { return "bad_weak_ptr"; } 36 37 #ifdef __GTHREADS 38 namespace 39 { 40 const unsigned char mask = 0xf; 41 const unsigned char invalid = mask + 1; 42 key(const void * addr)43 inline unsigned char key(const void* addr) 44 { return _Hash_impl::hash(addr) & mask; } 45 46 /* Returns different instances of __mutex depending on the passed address 47 * in order to limit contention. 48 */ 49 __gnu_cxx::__mutex& get_mutex(unsigned char i)50 get_mutex(unsigned char i) 51 { 52 static __gnu_cxx::__mutex m[mask + 1]; 53 return m[i]; 54 } 55 } 56 _Sp_locker(const void * p)57 _Sp_locker::_Sp_locker(const void* p) noexcept 58 { 59 if (__gthread_active_p()) 60 { 61 _M_key1 = _M_key2 = key(p); 62 get_mutex(_M_key1).lock(); 63 } 64 else 65 _M_key1 = _M_key2 = invalid; 66 } 67 _Sp_locker(const void * p1,const void * p2)68 _Sp_locker::_Sp_locker(const void* p1, const void* p2) noexcept 69 { 70 if (__gthread_active_p()) 71 { 72 _M_key1 = key(p1); 73 _M_key2 = key(p2); 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(); 79 } 80 else 81 _M_key1 = _M_key2 = invalid; 82 } 83 ~_Sp_locker()84 _Sp_locker::~_Sp_locker() 85 { 86 if (_M_key1 != invalid) 87 { 88 get_mutex(_M_key1).unlock(); 89 if (_M_key2 != _M_key1) 90 get_mutex(_M_key2).unlock(); 91 } 92 } 93 #endif 94 95 _GLIBCXX_END_NAMESPACE_VERSION 96 } // namespace 97