1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <algorithm>
#include <functional>
#include <iterator>
#include <type_traits>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/static_assert.h"
#include "mongo/stdx/functional.h"
#include "mongo/util/decoration_container.h"
#include "mongo/util/scopeguard.h"
namespace mongo {
/**
* Registry of decorations.
*
* A decoration registry corresponds to the "type" of a DecorationContainer. For example, if
* you have two registries, r1 and r2, a DecorationContainer constructed from r1 has instances
* the decorations declared on r1, and a DecorationContainer constructed from r2 has instances
* of the decorations declared on r2.
*/
template <typename DecoratedType>
class DecorationRegistry {
MONGO_DISALLOW_COPYING(DecorationRegistry);
public:
DecorationRegistry() = default;
/**
* Declares a decoration of type T, constructed with T's default constructor, and
* returns a descriptor for accessing that decoration.
*
* NOTE: T's destructor must not throw exceptions.
*/
template <typename T>
auto declareDecoration() {
MONGO_STATIC_ASSERT_MSG(std::is_nothrow_destructible<T>::value,
"Decorations must be nothrow destructible");
return
typename DecorationContainer<DecoratedType>::template DecorationDescriptorWithType<T>(
std::move(declareDecoration(
sizeof(T), std::alignment_of<T>::value, &constructAt<T>, &destroyAt<T>)));
}
size_t getDecorationBufferSizeBytes() const {
return _totalSizeBytes;
}
/**
* Constructs the decorations declared in this registry on the given instance of
* "decorable".
*
* Called by the DecorationContainer constructor. Do not call directly.
*/
void construct(DecorationContainer<DecoratedType>* const container) const {
using std::cbegin;
auto iter = cbegin(_decorationInfo);
auto cleanupFunction = [&iter, container, this ]() noexcept->void {
using std::crend;
std::for_each(std::make_reverse_iterator(iter),
crend(this->_decorationInfo),
[&](auto&& decoration) {
decoration.destructor(
container->getDecoration(decoration.descriptor));
});
};
auto cleanup = makeGuard(std::move(cleanupFunction));
using std::cend;
for (; iter != cend(_decorationInfo); ++iter) {
iter->constructor(container->getDecoration(iter->descriptor));
}
cleanup.dismiss();
}
/**
* Destroys the decorations declared in this registry on the given instance of "decorable".
*
* Called by the DecorationContainer destructor. Do not call directly.
*/
void destroy(DecorationContainer<DecoratedType>* const container) const noexcept try {
std::for_each(_decorationInfo.rbegin(), _decorationInfo.rend(), [&](auto&& decoration) {
decoration.destructor(container->getDecoration(decoration.descriptor));
});
} catch (...) {
std::terminate();
}
private:
/**
* Function that constructs (initializes) a single instance of a decoration.
*/
using DecorationConstructorFn = void (*)(void*);
/**
* Function that destroys (deinitializes) a single instance of a decoration.
*/
using DecorationDestructorFn = void (*)(void*);
struct DecorationInfo {
DecorationInfo() {}
DecorationInfo(
typename DecorationContainer<DecoratedType>::DecorationDescriptor inDescriptor,
DecorationConstructorFn inConstructor,
DecorationDestructorFn inDestructor)
: descriptor(std::move(inDescriptor)),
constructor(std::move(inConstructor)),
destructor(std::move(inDestructor)) {}
typename DecorationContainer<DecoratedType>::DecorationDescriptor descriptor;
DecorationConstructorFn constructor;
DecorationDestructorFn destructor;
};
using DecorationInfoVector = std::vector<DecorationInfo>;
template <typename T>
static void constructAt(void* location) {
new (location) T();
}
template <typename T>
static void destroyAt(void* location) {
static_cast<T*>(location)->~T();
}
/**
* Declares a decoration with given "constructor" and "destructor" functions,
* of "sizeBytes" bytes.
*
* NOTE: "destructor" must not throw exceptions.
*/
typename DecorationContainer<DecoratedType>::DecorationDescriptor declareDecoration(
const size_t sizeBytes,
const size_t alignBytes,
const DecorationConstructorFn constructor,
const DecorationDestructorFn destructor) {
const size_t misalignment = _totalSizeBytes % alignBytes;
if (misalignment) {
_totalSizeBytes += alignBytes - misalignment;
}
typename DecorationContainer<DecoratedType>::DecorationDescriptor result(_totalSizeBytes);
_decorationInfo.push_back(DecorationInfo(result, constructor, destructor));
_totalSizeBytes += sizeBytes;
return result;
}
DecorationInfoVector _decorationInfo;
size_t _totalSizeBytes{sizeof(void*)};
};
} // namespace mongo
|
