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
|
/**
* Copyright (C) 2017 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 "mongo/stdx/new.h"
namespace mongo {
/**
* Creates a new type with the same interface as T, but having the
* given alignment. Note that if the given alignment is less than
* alignof(T), the program is ill-formed. To ensure that your program
* is well formed, see WithAligmentAtLeast, which will not reduce
* alignment below the natural alignment of T.
*/
template <typename T, size_t alignment>
struct alignas(alignment) WithAlignment : T {
using T::T;
};
/**
* Creates a new type with the same interface as T, but having an
* alignment greater than or equal to the given alignment. To ensure
* that the program remains well formed, the alignment will not be
* reduced below the natural alignment for T.
*/
template <typename T, size_t alignment>
using WithAlignmentAtLeast = WithAlignment<T, std::max(alignof(T), alignment)>;
/**
* Creates a new type with the same interface as T but guaranteed to
* be aligned to at least the size of a cache line.
*/
template <typename T>
using CacheAligned = WithAlignmentAtLeast<T, stdx::hardware_destructive_interference_size>;
} // namespace mongo
|
