libstdc++: debug_allocator.h Source File

libstdc++

debug_allocator.h
Go to the documentation of this file.
1// Allocators -*- C++ -*-
2
3// Copyright (C) 2001-2026 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/*
26 * Copyright (c) 1996-1997
27 * Silicon Graphics Computer Systems, Inc.
28 *
29 * Permission to use, copy, modify, distribute and sell this software
30 * and its documentation for any purpose is hereby granted without fee,
31 * provided that the above copyright notice appear in all copies and
32 * that both that copyright notice and this permission notice appear
33 * in supporting documentation. Silicon Graphics makes no
34 * representations about the suitability of this software for any
35 * purpose. It is provided "as is" without express or implied warranty.
36 */
37
38/** @file ext/debug_allocator.h
39 * This file is a GNU extension to the Standard C++ Library.
40 */
41
42#ifndef _DEBUG_ALLOCATOR_H
43#define _DEBUG_ALLOCATOR_H 1
44
45#include <bits/requires_hosted.h> // GNU extensions are currently omitted
46
47#include <stdexcept>
48#include <bits/stdexcept_throw.h>
49#include <ext/alloc_traits.h>
50
51namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
52{
53_GLIBCXX_BEGIN_NAMESPACE_VERSION
54
55 /**
56 * @brief A meta-allocator with debugging bits.
57 * @ingroup allocators
58 *
59 * This is precisely the allocator defined in the C++03 Standard.
60 */
61 template<typename _Alloc>
62 class debug_allocator
63 {
64 template<typename> friend class debug_allocator;
65
66 typedef __alloc_traits<_Alloc> _Traits;
67
68 public:
69 typedef typename _Traits::size_type size_type;
70 typedef typename _Traits::difference_type difference_type;
71 typedef typename _Traits::pointer pointer;
72 typedef typename _Traits::const_pointer const_pointer;
73 typedef typename _Traits::reference reference;
74 typedef typename _Traits::const_reference const_reference;
75 typedef typename _Traits::value_type value_type;
76
77 template<typename _Up>
78 class rebind
79 {
80 typedef typename _Traits::template rebind<_Up>::other __other;
81
82 public:
83 typedef debug_allocator<__other> other;
84 };
85
86 private:
87 // _M_extra is the number of objects that correspond to the
88 // extra space where debug information is stored.
89 size_type _M_extra;
90
91 _Alloc _M_allocator;
92
93 template<typename _Alloc2,
94 typename = typename __alloc_traits<_Alloc2>::template
95 rebind<value_type>::other>
96 struct __convertible
97 { };
98
99 template<typename _Alloc2>
100 struct __convertible<_Alloc2, _Alloc>
101 {
102 typedef void* __type;
103 };
104
105 size_type _S_extra()
106 {
107 const std::size_t __obj_size = sizeof(value_type);
108 return (sizeof(size_type) + __obj_size - 1) / __obj_size;
109 }
110
111 public:
112 debug_allocator() : _M_extra(_S_extra()) { }
113
114 template<typename _Alloc2>
115 debug_allocator(const debug_allocator<_Alloc2>& __a2,
116 typename __convertible<_Alloc2>::__type = 0)
117 : _M_extra(_S_extra()), _M_allocator(__a2._M_allocator) { }
118
119 debug_allocator(const _Alloc& __a)
120 : _M_extra(_S_extra()), _M_allocator(__a) { }
121
122 _GLIBCXX_NODISCARD pointer
123 allocate(size_type __n)
124 {
125 pointer __res = _M_allocator.allocate(__n + _M_extra);
126 size_type* __ps = reinterpret_cast<size_type*>(__res);
127 *__ps = __n;
128 return __res + _M_extra;
129 }
130
131 _GLIBCXX_NODISCARD pointer
132 allocate(size_type __n, const void* __hint)
133 {
134 pointer __res = _M_allocator.allocate(__n + _M_extra, __hint);
135 size_type* __ps = reinterpret_cast<size_type*>(__res);
136 *__ps = __n;
137 return __res + _M_extra;
138 }
139
140 void
141 deallocate(pointer __p, size_type __n)
142 {
143 using std::__throw_runtime_error;
144 if (__p)
145 {
146 pointer __real_p = __p - _M_extra;
147 if (*reinterpret_cast<size_type*>(__real_p) != __n)
148 __throw_runtime_error("debug_allocator::deallocate wrong size");
149 _M_allocator.deallocate(__real_p, __n + _M_extra);
150 }
151 else
152 __throw_runtime_error("debug_allocator::deallocate null pointer");
153 }
154
155 void
156 construct(pointer __p, const value_type& __val)
157 { _Traits::construct(_M_allocator, __p, __val); }
158
159#if __cplusplus >= 201103L
160 template<typename _Tp, typename... _Args>
161 void
162 construct(_Tp* __p, _Args&&... __args)
163 {
164 _Traits::construct(_M_allocator, __p,
165 std::forward<_Args>(__args)...);
166 }
167#endif
168
169 template<typename _Tp>
170 void
171 destroy(_Tp* __p)
172 { _Traits::destroy(_M_allocator, __p); }
173
174 size_type
175 max_size() const throw()
176 { return _Traits::max_size(_M_allocator) - _M_extra; }
177
178 template<typename _Alloc2>
179 friend bool
180 operator==(const debug_allocator& __lhs,
181 const debug_allocator<_Alloc2>& __rhs) _GLIBCXX_NOTHROW
182 { return __lhs._M_allocator == debug_allocator(__rhs)._M_allocator; }
183
184#if __cpp_impl_three_way_comparison < 201907L
185 template<typename _Alloc2>
186 friend bool
187 operator!=(const debug_allocator& __lhs,
188 const debug_allocator<_Alloc2>& __rhs) _GLIBCXX_NOTHROW
189 { return !(__lhs == __rhs); }
190#endif
191 };
192
193_GLIBCXX_END_NAMESPACE_VERSION
194} // namespace
195
196#endif
stdexcept
stdexcept_throw.h
requires_hosted.h
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:72
__gnu_cxx
GNU extensions for public use.
__gnu_cxx::__alloc_traits
Uniform interface to C++98 and C++11 allocators.
Definition ext/alloc_traits.h:51
__gnu_cxx::__alloc_traits::max_size
static constexpr size_type max_size(const _Alloc &__a) noexcept
The maximum supported allocation size.
Definition bits/alloc_traits.h:494
alloc_traits.h