1// <experimental/memory_resource> -*- C++ -*-
3// Copyright (C) 2015-2016 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25/** @file experimental/memory_resource
26 * This is a TS C++ Library header.
29#ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE
30#define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1
36#include <experimental/bits/lfts_config.h>
39namespace experimental {
40inline namespace fundamentals_v2 {
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
44#define __cpp_lib_experimental_memory_resources 201402L
46 class memory_resource;
48 template <typename _Tp>
49 class polymorphic_allocator;
51 template <typename _Alloc>
52 class __resource_adaptor_imp;
54 template <typename _Alloc>
55 using resource_adaptor = __resource_adaptor_imp<
56 typename allocator_traits<_Alloc>::template rebind_alloc<char>>;
58 template <typename _Tp>
59 struct __uses_allocator_construction_helper;
61 // Global memory resources
62 memory_resource* new_delete_resource() noexcept;
63 memory_resource* null_memory_resource() noexcept;
65 // The default memory resource
66 memory_resource* get_default_resource() noexcept;
67 memory_resource* set_default_resource(memory_resource* __r) noexcept;
69 // Standard memory resources
71 // 8.5 Class memory_resource
75 static constexpr size_t _S_max_align = alignof(max_align_t);
78 virtual ~memory_resource() { }
81 allocate(size_t __bytes, size_t __alignment = _S_max_align)
82 { return do_allocate(__bytes, __alignment); }
85 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align)
86 { return do_deallocate(__p, __bytes, __alignment); }
89 is_equal(const memory_resource& __other) const noexcept
90 { return do_is_equal(__other); }
94 do_allocate(size_t __bytes, size_t __alignment) = 0;
97 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0;
100 do_is_equal(const memory_resource& __other) const noexcept = 0;
104 operator==(const memory_resource& __a,
105 const memory_resource& __b) noexcept
106 { return &__a == &__b || __a.is_equal(__b); }
109 operator!=(const memory_resource& __a,
110 const memory_resource& __b) noexcept
111 { return !(__a == __b); }
114 // 8.6 Class template polymorphic_allocator
116 class polymorphic_allocator
118 using __uses_alloc1_ = __uses_alloc1<memory_resource*>;
119 using __uses_alloc2_ = __uses_alloc2<memory_resource*>;
121 template<typename _Tp1, typename... _Args>
123 _M_construct(__uses_alloc0, _Tp1* __p, _Args&&... __args)
124 { ::new(__p) _Tp1(std::forward<_Args>(__args)...); }
126 template<typename _Tp1, typename... _Args>
128 _M_construct(__uses_alloc1_, _Tp1* __p, _Args&&... __args)
129 { ::new(__p) _Tp1(allocator_arg, this->resource(),
130 std::forward<_Args>(__args)...); }
132 template<typename _Tp1, typename... _Args>
134 _M_construct(__uses_alloc2_, _Tp1* __p, _Args&&... __args)
135 { ::new(__p) _Tp1(std::forward<_Args>(__args)...,
139 using value_type = _Tp;
141 polymorphic_allocator() noexcept
142 : _M_resource(get_default_resource())
145 polymorphic_allocator(memory_resource* __r)
147 { _GLIBCXX_DEBUG_ASSERT(__r); }
149 polymorphic_allocator(const polymorphic_allocator& __other) = default;
151 template <typename _Up>
152 polymorphic_allocator(const polymorphic_allocator<_Up>&
154 : _M_resource(__other.resource())
157 polymorphic_allocator&
158 operator=(const polymorphic_allocator& __rhs) = default;
160 _Tp* allocate(size_t __n)
161 { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
164 void deallocate(_Tp* __p, size_t __n)
165 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
167 template <typename _Tp1, typename... _Args> //used here
168 void construct(_Tp1* __p, _Args&&... __args)
170 auto __use_tag = __use_alloc<_Tp1, memory_resource*,
171 _Args...>(this->resource());
172 _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
175 // Specializations for pair using piecewise construction
176 template <typename _Tp1, typename _Tp2,
177 typename... _Args1, typename... _Args2>
178 void construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
179 tuple<_Args1...> __x,
180 tuple<_Args2...> __y)
183 __use_alloc<_Tp1, memory_resource*, _Args1...>(this->resource());
185 __use_alloc<_Tp2, memory_resource*, _Args2...>(this->resource());
187 ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct,
188 _M_construct_p(__x_use_tag, __x),
189 _M_construct_p(__y_use_tag, __y));
192 template <typename _Tp1, typename _Tp2>
193 void construct(pair<_Tp1,_Tp2>* __p)
194 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
196 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
197 void construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y)
198 { this->construct(__p, piecewise_construct,
199 forward_as_tuple(std::forward<_Up>(__x)),
200 forward_as_tuple(std::forward<_Vp>(__y))); }
202 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
203 void construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
204 { this->construct(__p, piecewise_construct, forward_as_tuple(__pr.first),
205 forward_as_tuple(__pr.second)); }
207 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
208 void construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr)
209 { this->construct(__p, piecewise_construct,
210 forward_as_tuple(std::forward<_Up>(__pr.first)),
211 forward_as_tuple(std::forward<_Vp>(__pr.second))); }
213 template <typename _Up>
214 void destroy(_Up* __p)
217 // Return a default-constructed allocator (no allocator propagation)
218 polymorphic_allocator select_on_container_copy_construction() const
219 { return polymorphic_allocator(); }
221 memory_resource* resource() const
222 { return _M_resource; }
225 template<typename _Tuple>
227 _M_construct_p(__uses_alloc0, _Tuple& __t)
228 { return std::move(__t); }
230 template<typename... _Args>
232 _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t)
233 { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)),
236 template<typename... _Args>
238 _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t)
239 { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); }
241 memory_resource* _M_resource;
244 template <class _Tp1, class _Tp2>
245 bool operator==(const polymorphic_allocator<_Tp1>& __a,
246 const polymorphic_allocator<_Tp2>& __b) noexcept
247 { return *__a.resource() == *__b.resource(); }
249 template <class _Tp1, class _Tp2>
250 bool operator!=(const polymorphic_allocator<_Tp1>& __a,
251 const polymorphic_allocator<_Tp2>& __b) noexcept
252 { return !(__a == __b); }
254 // 8.7.1 __resource_adaptor_imp
255 template <typename _Alloc>
256 class __resource_adaptor_imp : public memory_resource
258 static_assert(is_same<char,
259 typename allocator_traits<_Alloc>::value_type>::value,
260 "Allocator's value_type is char");
261 static_assert(is_same<char*,
262 typename allocator_traits<_Alloc>::pointer>::value,
263 "Allocator's pointer type is value_type*");
264 static_assert(is_same<const char*,
265 typename allocator_traits<_Alloc>::const_pointer>::value,
266 "Allocator's const_pointer type is value_type const*");
267 static_assert(is_same<void*,
268 typename allocator_traits<_Alloc>::void_pointer>::value,
269 "Allocator's void_pointer type is void*");
270 static_assert(is_same<const void*,
271 typename allocator_traits<_Alloc>::const_void_pointer>::value,
272 "Allocator's const_void_pointer type is void const*");
275 using allocator_type = _Alloc;
277 __resource_adaptor_imp() = default;
278 __resource_adaptor_imp(const __resource_adaptor_imp&) = default;
279 __resource_adaptor_imp(__resource_adaptor_imp&&) = default;
281 explicit __resource_adaptor_imp(const _Alloc& __a2)
285 explicit __resource_adaptor_imp(_Alloc&& __a2)
286 : _M_alloc(std::move(__a2))
289 __resource_adaptor_imp&
290 operator=(const __resource_adaptor_imp&) = default;
292 allocator_type get_allocator() const noexcept { return _M_alloc; }
296 do_allocate(size_t __bytes, size_t __alignment)
298 using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
299 size_t __new_size = _S_aligned_size(__bytes,
300 _S_supported(__alignment) ?
301 __alignment : _S_max_align);
302 return _Aligned_alloc(_M_alloc).allocate(__new_size);
306 do_deallocate(void* __p, size_t __bytes, size_t __alignment)
308 using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
309 size_t __new_size = _S_aligned_size(__bytes,
310 _S_supported(__alignment) ?
311 __alignment : _S_max_align);
312 using _Ptr = typename allocator_traits<_Aligned_alloc>::pointer;
313 _Aligned_alloc(_M_alloc).deallocate(static_cast<_Ptr>(__p),
318 do_is_equal(const memory_resource& __other) const noexcept
320 auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other);
321 return __p ? (_M_alloc == __p->_M_alloc) : false;
325 // Calculate Aligned Size
326 // Returns a size that is larger than or equal to __size and divisible
327 // by __alignment, where __alignment is required to be a power of 2.
329 _S_aligned_size(size_t __size, size_t __alignment)
330 { return ((__size - 1)|(__alignment - 1)) + 1; }
332 // Determine whether alignment meets one of those preconditions:
334 // 2. Is power of two
336 _S_supported (size_t __x)
337 { return ((__x != 0) && !(__x & (__x - 1))); }
342 // Global memory resources
344 inline memory_resource*
345 new_delete_resource() noexcept
347 using type = resource_adaptor<std::allocator<char>>;
348 alignas(type) static unsigned char __buf[sizeof(type)];
349 static type* __r = new(__buf) type;
353 inline memory_resource*
354 null_memory_resource() noexcept
356 class type final : public memory_resource
359 do_allocate(size_t, size_t) override
360 { std::__throw_bad_alloc(); }
363 do_deallocate(void*, size_t, size_t) noexcept override
367 do_is_equal(const memory_resource& __other) const noexcept override
368 { return this == &__other; }
371 alignas(type) static unsigned char __buf[sizeof(type)];
372 static type* __r = new(__buf) type;
376 // The default memory resource
378 inline std::atomic<memory_resource*>&
379 __get_default_resource()
381 using type = atomic<memory_resource*>;
382 alignas(type) static unsigned char __buf[sizeof(type)];
383 static type* __r = new(__buf) type(new_delete_resource());
387 inline memory_resource*
388 get_default_resource() noexcept
389 { return __get_default_resource().load(); }
391 inline memory_resource*
392 set_default_resource(memory_resource* __r) noexcept
395 __r = new_delete_resource();
396 return __get_default_resource().exchange(__r);
399_GLIBCXX_END_NAMESPACE_VERSION
401} // namespace fundamentals_v2
402} // namespace experimental