]>
Commit | Line | Data |
---|---|---|
12471842 PL |
1 | /* |
2 | * This file is part of PowerDNS or dnsdist. | |
3 | * Copyright -- PowerDNS.COM B.V. and its contributors | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of version 2 of the GNU General Public License as | |
7 | * published by the Free Software Foundation. | |
8 | * | |
9 | * In addition, for the avoidance of any doubt, permission is granted to | |
10 | * link this program with OpenSSL and to (re)distribute the binaries | |
11 | * produced as the result of such linking. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
21 | */ | |
5cf909f3 AN |
22 | #ifndef LAZY_ALLOCATOR_HH |
23 | #define LAZY_ALLOCATOR_HH | |
24 | ||
25 | #include <cstddef> | |
26 | #include <utility> | |
27 | #include <type_traits> | |
15880e10 OM |
28 | #include <new> |
29 | #include <sys/mman.h> | |
30 | ||
31 | // On OpenBSD mem used as stack should be marked MAP_STACK | |
32 | #if !defined(MAP_STACK) | |
33 | #define MAP_STACK 0 | |
34 | #endif | |
5cf909f3 AN |
35 | |
36 | template <typename T> | |
37 | struct lazy_allocator { | |
38 | using value_type = T; | |
39 | using pointer = T*; | |
40 | using size_type = std::size_t; | |
41 | static_assert (std::is_trivial<T>::value, | |
42 | "lazy_allocator must only be used with trivial types"); | |
43 | ||
44 | pointer | |
45 | allocate (size_type const n) { | |
584ab041 | 46 | #ifdef __OpenBSD__ |
70a29b7d | 47 | void *p = mmap(nullptr, n * sizeof(value_type), |
15880e10 OM |
48 | PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0); |
49 | if (p == MAP_FAILED) | |
50 | throw std::bad_alloc(); | |
51 | return static_cast<pointer>(p); | |
584ab041 OM |
52 | #else |
53 | return static_cast<pointer>(::operator new (n * sizeof(value_type))); | |
54 | #endif | |
5cf909f3 AN |
55 | } |
56 | ||
57 | void | |
58 | deallocate (pointer const ptr, size_type const n) noexcept { | |
584ab041 | 59 | #ifdef __OpenBSD__ |
15880e10 | 60 | munmap(ptr, n * sizeof(value_type)); |
584ab041 OM |
61 | #else |
62 | #if defined(__cpp_sized_deallocation) && (__cpp_sized_deallocation >= 201309) | |
63 | ::operator delete (ptr, n * sizeof(value_type)); | |
64 | #else | |
65 | (void) n; | |
66 | ::operator delete (ptr); | |
67 | #endif | |
68 | #endif | |
5cf909f3 AN |
69 | } |
70 | ||
71 | void construct (T*) const noexcept {} | |
72 | ||
73 | template <typename X, typename... Args> | |
74 | void | |
75 | construct (X* place, Args&&... args) const noexcept { | |
76 | new (static_cast<void*>(place)) X (std::forward<Args>(args)...); | |
77 | } | |
78 | }; | |
79 | ||
80 | template <typename T> inline | |
81 | bool operator== (lazy_allocator<T> const&, lazy_allocator<T> const&) noexcept { | |
82 | return true; | |
83 | } | |
84 | ||
85 | template <typename T> inline | |
86 | bool operator!= (lazy_allocator<T> const&, lazy_allocator<T> const&) noexcept { | |
87 | return false; | |
88 | } | |
89 | ||
90 | #endif // LAZY_ALLOCATOR_HH |