1 // Support for pointer abstractions -*- C++ -*- 2 3 // Copyright (C) 2011-2022 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 #include "mutex_pool.h" 28 29 namespace __gnu_internal _GLIBCXX_VISIBILITY(hidden) 30 { 31 /* Returns different instances of __mutex depending on the passed index 32 * in order to limit contention. 33 */ 34 __gnu_cxx::__mutex& get_mutex(unsigned char i)35 get_mutex(unsigned char i) 36 { 37 // increase alignment to put each lock on a separate cache line 38 struct alignas(64) M : __gnu_cxx::__mutex { }; 39 static M m[mask + 1]; 40 return m[i]; 41 } 42 } 43 44 namespace std _GLIBCXX_VISIBILITY(default) 45 { 46 _GLIBCXX_BEGIN_NAMESPACE_VERSION 47 48 bad_weak_ptr::~bad_weak_ptr() noexcept = default; 49 50 char const* what() const51 bad_weak_ptr::what() const noexcept 52 { return "bad_weak_ptr"; } 53 54 #ifdef __GTHREADS 55 namespace 56 { key(const void * addr)57 inline unsigned char key(const void* addr) 58 { return _Hash_impl::hash(addr) & __gnu_internal::mask; } 59 } 60 _Sp_locker(const void * p)61 _Sp_locker::_Sp_locker(const void* p) noexcept 62 { 63 if (__gthread_active_p()) 64 { 65 _M_key1 = _M_key2 = key(p); 66 __gnu_internal::get_mutex(_M_key1).lock(); 67 } 68 else 69 _M_key1 = _M_key2 = __gnu_internal::invalid; 70 } 71 _Sp_locker(const void * p1,const void * p2)72 _Sp_locker::_Sp_locker(const void* p1, const void* p2) noexcept 73 { 74 if (__gthread_active_p()) 75 { 76 _M_key1 = key(p1); 77 _M_key2 = key(p2); 78 if (_M_key2 < _M_key1) 79 __gnu_internal::get_mutex(_M_key2).lock(); 80 __gnu_internal::get_mutex(_M_key1).lock(); 81 if (_M_key2 > _M_key1) 82 __gnu_internal::get_mutex(_M_key2).lock(); 83 } 84 else 85 _M_key1 = _M_key2 = __gnu_internal::invalid; 86 } 87 ~_Sp_locker()88 _Sp_locker::~_Sp_locker() 89 { 90 if (_M_key1 != __gnu_internal::invalid) 91 { 92 __gnu_internal::get_mutex(_M_key1).unlock(); 93 if (_M_key2 != _M_key1) 94 __gnu_internal::get_mutex(_M_key2).unlock(); 95 } 96 } 97 #endif 98 99 bool _S_eq(const type_info & ti)100 _Sp_make_shared_tag::_S_eq(const type_info& ti [[gnu::unused]]) noexcept 101 { 102 #if __cpp_rtti 103 return ti == typeid(_Sp_make_shared_tag); 104 #else 105 // If libstdc++ itself is built with -fno-rtti then just assume that 106 // make_shared and allocate_shared will never be used with -frtti. 107 return false; 108 #endif 109 } 110 111 _GLIBCXX_END_NAMESPACE_VERSION 112 } // namespace 113