MySQL 8.0.31
Source Code Documentation
component_malloc_allocator.h
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2
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4 it under the terms of the GNU General Public License, version 2.0,
5 as published by the Free Software Foundation.
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9 as designated in a particular file or component or in included license
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12 separately licensed software that they have included with MySQL.
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15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License, version 2.0, for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
22
23#ifndef COMPONENT_MALLOC_ALLOCATOR_INCLUDED
24#define COMPONENT_MALLOC_ALLOCATOR_INCLUDED
25
26#include <assert.h>
28#include <limits>
29#include <new>
30#include <utility> // std::forward
31#include "my_compiler.h"
32
33/**
34 Component_malloc_allocator is a C++ STL memory allocator based on
35 my_malloc/my_free.
36
37 This allows for P_S instrumentation of memory allocation done
38 internally by STL container classes in components.
39
40 Example usage:
41 vector<int, Component_malloc_allocator<int>>
42 v((Component_malloc_allocator<int>(PSI_NOT_INSTRUMENTED)));
43
44 If the type is complicated, you can just write
45 Component_malloc_allocator<>(psi_key) as a shorthand for
46 Component_malloc_allocator<My_complicated_type>(psi_key), as all
47 Component_malloc_allocator instances are implicitly convertible to each other
48 and there is a default template parameter.
49
50 @note allocate() throws std::bad_alloc() similarly to the default
51 STL memory allocator. This is necessary - STL functions which allocates
52 memory expects it. Otherwise these functions will try to use the memory,
53 leading to segfaults if memory allocation was not successful.
54
55 @note This allocator cannot be used for std::basic_string with RHEL 6/7
56 because of this bug:
57 https://bugzilla.redhat.com/show_bug.cgi?id=1546704
58 "Define _GLIBCXX_USE_CXX11_ABI gets ignored by gcc in devtoolset-7"
59*/
60
61template <class T = void *>
63 // This cannot be const if we want to be able to swap.
65
66 public:
67 typedef T value_type;
68 typedef size_t size_type;
69 typedef ptrdiff_t difference_type;
70
71 typedef T *pointer;
72 typedef const T *const_pointer;
73
74 typedef T &reference;
75 typedef const T &const_reference;
76
77 pointer address(reference r) const { return &r; }
79
81
82 template <class U>
84 : m_key(other.psi_key()) {}
85
86 template <class U>
87 // on release builds assert is not evaluated. So compilation error is seen,
88 // hence used 'unused' attribute.
90 const Component_malloc_allocator<U> &other [[maybe_unused]]) {
91 assert(m_key == other.psi_key()); // Don't swap key.
92 }
93
95 if (n == 0) return nullptr;
96 if (n > max_size()) throw std::bad_alloc();
97
98 pointer p = static_cast<pointer>(my_malloc(m_key, n * sizeof(T), 0));
99 if (p == nullptr) throw std::bad_alloc();
100 return p;
101 }
102
104
105 template <class U, class... Args>
106 void construct(U *p, Args &&... args) {
107 assert(p != nullptr);
108 try {
109 ::new ((void *)p) U(std::forward<Args>(args)...);
110 } catch (...) {
111 assert(false); // Constructor should not throw an exception.
112 }
113 }
114
116 assert(p != nullptr);
117 try {
118 p->~T();
119 } catch (...) {
120 assert(false); // Destructor should not throw an exception
121 }
122 }
123
125 return std::numeric_limits<size_t>::max() / sizeof(T);
126 }
127
128 template <class U>
129 struct rebind {
131 };
132
133 PSI_memory_key psi_key() const { return m_key; }
134};
135
136template <class T>
139 return a1.psi_key() == a2.psi_key();
140}
141
142template <class T>
145 return a1.psi_key() != a2.psi_key();
146}
147
148#endif // COMPONENT_MALLOC_ALLOCATOR_INCLUDED
Component_malloc_allocator is a C++ STL memory allocator based on my_malloc/my_free.
Definition: component_malloc_allocator.h:62
void destroy(pointer p)
Definition: component_malloc_allocator.h:115
PSI_memory_key psi_key() const
Definition: component_malloc_allocator.h:133
const_pointer address(const_reference r) const
Definition: component_malloc_allocator.h:78
void deallocate(pointer p, size_type)
Definition: component_malloc_allocator.h:103
pointer allocate(size_type n, const_pointer=nullptr)
Definition: component_malloc_allocator.h:94
T value_type
Definition: component_malloc_allocator.h:67
void construct(U *p, Args &&... args)
Definition: component_malloc_allocator.h:106
T & reference
Definition: component_malloc_allocator.h:74
size_t size_type
Definition: component_malloc_allocator.h:68
ptrdiff_t difference_type
Definition: component_malloc_allocator.h:69
const T & const_reference
Definition: component_malloc_allocator.h:75
PSI_memory_key m_key
Definition: component_malloc_allocator.h:64
Component_malloc_allocator(PSI_memory_key key)
Definition: component_malloc_allocator.h:80
Component_malloc_allocator(const Component_malloc_allocator< U > &other)
Definition: component_malloc_allocator.h:83
Component_malloc_allocator & operator=(const Component_malloc_allocator< U > &other)
Definition: component_malloc_allocator.h:89
const T * const_pointer
Definition: component_malloc_allocator.h:72
pointer address(reference r) const
Definition: component_malloc_allocator.h:77
T * pointer
Definition: component_malloc_allocator.h:71
size_type max_size() const
Definition: component_malloc_allocator.h:124
bool operator!=(const Component_malloc_allocator< T > &a1, const Component_malloc_allocator< T > &a2)
Definition: component_malloc_allocator.h:143
bool operator==(const Component_malloc_allocator< T > &a1, const Component_malloc_allocator< T > &a2)
Definition: component_malloc_allocator.h:137
const char * p
Definition: ctype-mb.cc:1236
#define U
Definition: ctype-tis620.cc:74
unsigned int PSI_memory_key
Instrumented memory key.
Definition: psi_memory_bits.h:48
Header for compiler-dependent features.
void * my_malloc(PSI_memory_key key, size_t size, int flags)
Allocates size bytes of memory.
Definition: my_memory.cc:56
void my_free(void *ptr)
Frees the memory pointed by the ptr.
Definition: my_memory.cc:80
const mysql_service_registry_t * r
Definition: pfs_example_plugin_employee.cc:85
required string key
Definition: replication_asynchronous_connection_failover.proto:59
Definition: component_malloc_allocator.h:129
Component_malloc_allocator< U > other
Definition: component_malloc_allocator.h:130
Definition: dtoa.cc:594
int n
Definition: xcom_base.cc:505