source: Daodan/MSYS2/mingw32/include/c++/11.2.0/experimental/memory_resource@ 1186

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1// <experimental/memory_resource> -*- C++ -*-
2
3// Copyright (C) 2015-2021 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/** @file experimental/memory_resource
26 * This is a TS C++ Library header.
27 * @ingroup libfund-ts
28 */
29
30#ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE
31#define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1
32
33#pragma GCC system_header
34
35#if __cplusplus >= 201402L
36
37#include <memory> // align, uses_allocator, __uses_alloc
38#include <experimental/utility> // pair, experimental::erased_type
39#include <tuple> // tuple, forward_as_tuple
40#include <atomic> // atomic
41#include <new> // placement new
42#include <cstddef> // max_align_t
43#include <ext/new_allocator.h>
44#include <debug/assertions.h>
45
46/// @cond
47namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
48{
49_GLIBCXX_BEGIN_NAMESPACE_VERSION
50 template<typename _Tp> class malloc_allocator;
51_GLIBCXX_END_NAMESPACE_VERSION
52} // namespace __gnu_cxx
53/// @endcond
54
55namespace std {
56_GLIBCXX_BEGIN_NAMESPACE_VERSION
57
58namespace experimental {
59inline namespace fundamentals_v2 {
60namespace pmr {
61#define __cpp_lib_experimental_memory_resources 201402L
62
63 // Standard memory resources
64
65 // 8.5 Class memory_resource
66 class memory_resource;
67
68 // 8.6 Class template polymorphic_allocator
69 template<typename _Tp>
70 class polymorphic_allocator;
71
72 template<typename _Alloc, typename _Resource = memory_resource>
73 class __resource_adaptor_imp;
74
75 // 8.7 Alias template resource_adaptor
76 template<typename _Alloc>
77 using resource_adaptor = __resource_adaptor_imp<
78 typename allocator_traits<_Alloc>::template rebind_alloc<char>>;
79
80 // 8.8 Global memory resources
81 memory_resource* new_delete_resource() noexcept;
82 memory_resource* null_memory_resource() noexcept;
83 memory_resource* get_default_resource() noexcept;
84 memory_resource* set_default_resource(memory_resource* __r) noexcept;
85
86 // TODO 8.9 Pool resource classes
87
88 class memory_resource
89 {
90 static constexpr size_t _S_max_align = alignof(max_align_t);
91
92 public:
93 memory_resource() = default;
94 memory_resource(const memory_resource&) = default;
95 virtual ~memory_resource() = default;
96
97 memory_resource& operator=(const memory_resource&) = default;
98
99 _GLIBCXX_NODISCARD void*
100 allocate(size_t __bytes, size_t __alignment = _S_max_align)
101 { return do_allocate(__bytes, __alignment); }
102
103 void
104 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align)
105 { return do_deallocate(__p, __bytes, __alignment); }
106
107 bool
108 is_equal(const memory_resource& __other) const noexcept
109 { return do_is_equal(__other); }
110
111 protected:
112 virtual void*
113 do_allocate(size_t __bytes, size_t __alignment) = 0;
114
115 virtual void
116 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0;
117
118 virtual bool
119 do_is_equal(const memory_resource& __other) const noexcept = 0;
120 };
121
122 inline bool
123 operator==(const memory_resource& __a, const memory_resource& __b) noexcept
124 { return &__a == &__b || __a.is_equal(__b); }
125
126 inline bool
127 operator!=(const memory_resource& __a, const memory_resource& __b) noexcept
128 { return !(__a == __b); }
129
130
131 template<typename _Tp>
132 class polymorphic_allocator
133 {
134 public:
135 using value_type = _Tp;
136
137 polymorphic_allocator() noexcept
138 : _M_resource(get_default_resource())
139 { }
140
141 polymorphic_allocator(memory_resource* __r)
142 : _M_resource(__r)
143 { _GLIBCXX_DEBUG_ASSERT(__r); }
144
145 polymorphic_allocator(const polymorphic_allocator& __other) = default;
146
147 template <typename _Up>
148 polymorphic_allocator(const polymorphic_allocator<_Up>&
149 __other) noexcept
150 : _M_resource(__other.resource())
151 { }
152
153 polymorphic_allocator&
154 operator=(const polymorphic_allocator& __rhs) = default;
155
156 _GLIBCXX_NODISCARD _Tp* allocate(size_t __n)
157 { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
158 alignof(_Tp))); }
159
160 void
161 deallocate(_Tp* __p, size_t __n)
162 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
163
164 template <typename _Tp1, typename... _Args> //used here
165 void
166 construct(_Tp1* __p, _Args&&... __args)
167 {
168 std::__uses_allocator_construct(this->resource(), __p,
169 std::forward<_Args>(__args)...);
170 }
171
172 // Specializations for pair using piecewise construction
173 template <typename _Tp1, typename _Tp2,
174 typename... _Args1, typename... _Args2>
175 void
176 construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
177 tuple<_Args1...> __x, tuple<_Args2...> __y)
178 {
179 memory_resource* const __resource = this->resource();
180 auto __x_use_tag =
181 std::__use_alloc<_Tp1, memory_resource*, _Args1...>(__resource);
182 auto __y_use_tag =
183 std::__use_alloc<_Tp2, memory_resource*, _Args2...>(__resource);
184
185 ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct,
186 _M_construct_p(__x_use_tag, __x),
187 _M_construct_p(__y_use_tag, __y));
188 }
189
190 template <typename _Tp1, typename _Tp2>
191 void
192 construct(pair<_Tp1,_Tp2>* __p)
193 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
194
195 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
196 void
197 construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y)
198 {
199 this->construct(__p, piecewise_construct,
200 std::forward_as_tuple(std::forward<_Up>(__x)),
201 std::forward_as_tuple(std::forward<_Vp>(__y)));
202 }
203
204 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
205 void
206 construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
207 {
208 this->construct(__p, piecewise_construct,
209 std::forward_as_tuple(__pr.first),
210 std::forward_as_tuple(__pr.second));
211 }
212
213 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
214 void
215 construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr)
216 {
217 this->construct(__p, piecewise_construct,
218 std::forward_as_tuple(std::forward<_Up>(__pr.first)),
219 std::forward_as_tuple(std::forward<_Vp>(__pr.second)));
220 }
221
222 template <typename _Up>
223 void
224 destroy(_Up* __p)
225 { __p->~_Up(); }
226
227 // Return a default-constructed allocator (no allocator propagation)
228 polymorphic_allocator
229 select_on_container_copy_construction() const
230 { return polymorphic_allocator(); }
231
232 memory_resource* resource() const { return _M_resource; }
233
234 private:
235 using __uses_alloc1_ = __uses_alloc1<memory_resource*>;
236 using __uses_alloc2_ = __uses_alloc2<memory_resource*>;
237
238 template<typename _Tuple>
239 _Tuple&&
240 _M_construct_p(__uses_alloc0, _Tuple& __t)
241 { return std::move(__t); }
242
243 template<typename... _Args>
244 decltype(auto)
245 _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t)
246 { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)),
247 std::move(__t)); }
248
249 template<typename... _Args>
250 decltype(auto)
251 _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t)
252 { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); }
253
254 memory_resource* _M_resource;
255 };
256
257 template <class _Tp1, class _Tp2>
258 bool
259 operator==(const polymorphic_allocator<_Tp1>& __a,
260 const polymorphic_allocator<_Tp2>& __b) noexcept
261 { return *__a.resource() == *__b.resource(); }
262
263 template <class _Tp1, class _Tp2>
264 bool
265 operator!=(const polymorphic_allocator<_Tp1>& __a,
266 const polymorphic_allocator<_Tp2>& __b) noexcept
267 { return !(__a == __b); }
268
269
270 /// @cond undocumented
271 class __resource_adaptor_common
272 {
273 template<typename, typename> friend class __resource_adaptor_imp;
274
275 struct _AlignMgr
276 {
277 _AlignMgr(size_t __nbytes, size_t __align)
278 : _M_nbytes(__nbytes), _M_align(__align)
279 { }
280
281 // Total size that needs to be allocated.
282 size_t
283 _M_alloc_size() const { return _M_buf_size() + _M_token_size(); }
284
285 void*
286 _M_adjust(void* __ptr) const
287 {
288 const auto __orig_ptr = static_cast<char*>(__ptr);
289 size_t __space = _M_buf_size();
290 // Align the pointer within the buffer:
291 std::align(_M_align, _M_nbytes, __ptr, __space);
292 const auto __aligned_ptr = static_cast<char*>(__ptr);
293 const auto __token_size = _M_token_size();
294 // Store token immediately after the aligned block:
295 char* const __end = __aligned_ptr + _M_nbytes;
296 if (__token_size == 1)
297 _S_write<unsigned char>(__end, __aligned_ptr - __orig_ptr);
298 else if (__token_size == sizeof(short))
299 _S_write<unsigned short>(__end, __aligned_ptr - __orig_ptr);
300 else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*))
301 _S_write<unsigned int>(__end, __aligned_ptr - __orig_ptr);
302 else // (__token_size == sizeof(char*))
303 // Just store the original pointer:
304 _S_write<char*>(__end, __orig_ptr);
305 return __aligned_ptr;
306 }
307
308 char*
309 _M_unadjust(char* __ptr) const
310 {
311 const char* const __end = __ptr + _M_nbytes;
312 char* __orig_ptr;
313 const auto __token_size = _M_token_size();
314 // Read the token and restore the original pointer:
315 if (__token_size == 1)
316 __orig_ptr = __ptr - _S_read<unsigned char>(__end);
317 else if (__token_size == sizeof(short))
318 __orig_ptr = __ptr - _S_read<unsigned short>(__end);
319 else if (__token_size == sizeof(int)
320 && sizeof(int) < sizeof(char*))
321 __orig_ptr = __ptr - _S_read<unsigned int>(__end);
322 else // (__token_size == sizeof(char*))
323 __orig_ptr = _S_read<char*>(__end);
324 // The adjustment is always less than the requested alignment,
325 // so if that isn't true now then either the wrong size was passed
326 // to deallocate or the token was overwritten by a buffer overflow:
327 __glibcxx_assert(static_cast<size_t>(__ptr - __orig_ptr) < _M_align);
328 return __orig_ptr;
329 }
330
331 private:
332 size_t _M_nbytes;
333 size_t _M_align;
334
335 // Number of bytes needed to fit block of given size and alignment.
336 size_t
337 _M_buf_size() const { return _M_nbytes + _M_align - 1; }
338
339 // Number of additional bytes needed to write the token.
340 int
341 _M_token_size() const
342 {
343 if (_M_align <= (1ul << __CHAR_BIT__))
344 return 1;
345 if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__)))
346 return sizeof(short);
347 if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__)))
348 return sizeof(int);
349 return sizeof(char*);
350 }
351
352 template<typename _Tp>
353 static void
354 _S_write(void* __to, _Tp __val)
355 { __builtin_memcpy(__to, &__val, sizeof(_Tp)); }
356
357 template<typename _Tp>
358 static _Tp
359 _S_read(const void* __from)
360 {
361 _Tp __val;
362 __builtin_memcpy(&__val, __from, sizeof(_Tp));
363 return __val;
364 }
365 };
366 };
367 /// @endcond
368
369 // 8.7.1 __resource_adaptor_imp
370 template<typename _Alloc, typename _Resource>
371 class __resource_adaptor_imp
372 : public _Resource, private __resource_adaptor_common
373 {
374 using memory_resource = _Resource;
375
376 static_assert(is_same<char,
377 typename allocator_traits<_Alloc>::value_type>::value,
378 "Allocator's value_type is char");
379 static_assert(is_same<char*,
380 typename allocator_traits<_Alloc>::pointer>::value,
381 "Allocator's pointer type is value_type*");
382 static_assert(is_same<const char*,
383 typename allocator_traits<_Alloc>::const_pointer>::value,
384 "Allocator's const_pointer type is value_type const*");
385 static_assert(is_same<void*,
386 typename allocator_traits<_Alloc>::void_pointer>::value,
387 "Allocator's void_pointer type is void*");
388 static_assert(is_same<const void*,
389 typename allocator_traits<_Alloc>::const_void_pointer>::value,
390 "Allocator's const_void_pointer type is void const*");
391
392 public:
393 using allocator_type = _Alloc;
394
395 __resource_adaptor_imp() = default;
396 __resource_adaptor_imp(const __resource_adaptor_imp&) = default;
397 __resource_adaptor_imp(__resource_adaptor_imp&&) = default;
398
399 explicit __resource_adaptor_imp(const _Alloc& __a2)
400 : _M_alloc(__a2)
401 { }
402
403 explicit __resource_adaptor_imp(_Alloc&& __a2)
404 : _M_alloc(std::move(__a2))
405 { }
406
407 __resource_adaptor_imp&
408 operator=(const __resource_adaptor_imp&) = default;
409
410 allocator_type get_allocator() const noexcept { return _M_alloc; }
411
412 protected:
413 virtual void*
414 do_allocate(size_t __bytes, size_t __alignment) override
415 {
416 // Cannot use max_align_t on 32-bit Solaris x86, see PR libstdc++/77691
417#if ! ((defined __sun__ || defined __VXWORKS__) && defined __i386__)
418 if (__alignment == alignof(max_align_t))
419 return _M_allocate<alignof(max_align_t)>(__bytes);
420#endif
421 switch (__alignment)
422 {
423 case 1:
424 return _M_alloc.allocate(__bytes);
425 case 2:
426 return _M_allocate<2>(__bytes);
427 case 4:
428 return _M_allocate<4>(__bytes);
429 case 8:
430 return _M_allocate<8>(__bytes);
431 }
432 const _AlignMgr __mgr(__bytes, __alignment);
433 // Assume _M_alloc returns 1-byte aligned memory, so allocate enough
434 // space to fit a block of the right size and alignment, plus some
435 // extra bytes to store a token for retrieving the original pointer.
436 return __mgr._M_adjust(_M_alloc.allocate(__mgr._M_alloc_size()));
437 }
438
439 virtual void
440 do_deallocate(void* __ptr, size_t __bytes, size_t __alignment) noexcept
441 override
442 {
443#if ! ((defined __sun__ || defined __VXWORKS__) && defined __i386__)
444 if (__alignment == alignof(max_align_t))
445 return (void) _M_deallocate<alignof(max_align_t)>(__ptr, __bytes);
446#endif
447 switch (__alignment)
448 {
449 case 1:
450 return (void) _M_alloc.deallocate((char*)__ptr, __bytes);
451 case 2:
452 return (void) _M_deallocate<2>(__ptr, __bytes);
453 case 4:
454 return (void) _M_deallocate<4>(__ptr, __bytes);
455 case 8:
456 return (void) _M_deallocate<8>(__ptr, __bytes);
457 }
458 const _AlignMgr __mgr(__bytes, __alignment);
459 // Use the stored token to retrieve the original pointer.
460 _M_alloc.deallocate(__mgr._M_unadjust((char*)__ptr),
461 __mgr._M_alloc_size());
462 }
463
464 virtual bool
465 do_is_equal(const memory_resource& __other) const noexcept override
466 {
467 if (auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other))
468 return _M_alloc == __p->_M_alloc;
469 return false;
470 }
471
472 private:
473 template<size_t _Num>
474 struct _Aligned_type { alignas(_Num) char __c[_Num]; };
475
476 // Rebind the allocator to the specified type and use it to allocate.
477 template<size_t _Num, typename _Tp = _Aligned_type<_Num>>
478 void*
479 _M_allocate(size_t __bytes)
480 {
481 typename allocator_traits<_Alloc>::template
482 rebind_alloc<_Tp> __a2(_M_alloc);
483 const size_t __n = (__bytes + _Num - 1) / _Num;
484 return __a2.allocate(__n);
485 }
486
487 // Rebind the allocator to the specified type and use it to deallocate.
488 template<size_t _Num, typename _Tp = _Aligned_type<_Num>>
489 void
490 _M_deallocate(void* __ptr, size_t __bytes) noexcept
491 {
492 typename allocator_traits<_Alloc>::template
493 rebind_alloc<_Tp> __a2(_M_alloc);
494 const size_t __n = (__bytes + _Num - 1) / _Num;
495 __a2.deallocate((_Tp*)__ptr, __n);
496 }
497
498 _Alloc _M_alloc{};
499 };
500
501 // Global memory resources
502
503 inline memory_resource*
504 new_delete_resource() noexcept
505 {
506 using type = resource_adaptor<__gnu_cxx::new_allocator<char>>;
507 alignas(type) static unsigned char __buf[sizeof(type)];
508 static type* __r = new(__buf) type;
509 return __r;
510 }
511
512 inline memory_resource*
513 null_memory_resource() noexcept
514 {
515 class type final : public memory_resource
516 {
517 void*
518 do_allocate(size_t, size_t) override
519 { std::__throw_bad_alloc(); }
520
521 void
522 do_deallocate(void*, size_t, size_t) noexcept override
523 { }
524
525 bool
526 do_is_equal(const memory_resource& __other) const noexcept override
527 { return this == &__other; }
528 };
529
530 alignas(type) static unsigned char __buf[sizeof(type)];
531 static type* __r = new(__buf) type;
532 return __r;
533 }
534
535 // The default memory resource
536
537 /// @cond undocumented
538 inline std::atomic<memory_resource*>&
539 __get_default_resource()
540 {
541 using type = atomic<memory_resource*>;
542 alignas(type) static unsigned char __buf[sizeof(type)];
543 static type* __r = new(__buf) type(new_delete_resource());
544 return *__r;
545 }
546 /// @endcond
547
548 /// Get the current default resource.
549 inline memory_resource*
550 get_default_resource() noexcept
551 { return __get_default_resource().load(); }
552
553 /// Change the default resource and return the previous one.
554 inline memory_resource*
555 set_default_resource(memory_resource* __r) noexcept
556 {
557 if (__r == nullptr)
558 __r = new_delete_resource();
559 return __get_default_resource().exchange(__r);
560 }
561
562} // namespace pmr
563} // namespace fundamentals_v2
564} // namespace experimental
565
566_GLIBCXX_END_NAMESPACE_VERSION
567} // namespace std
568#endif // C++14
569#endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE
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