1 // <experimental/memory_resource> -*- C++ -*-
3 // Copyright (C) 2015-2018 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
32 #pragma GCC system_header
34 #if __cplusplus >= 201402L
40 #include <experimental/bits/lfts_config.h>
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
45 namespace experimental {
46 inline namespace fundamentals_v2 {
48 #define __cpp_lib_experimental_memory_resources 201402L
50 class memory_resource;
52 template <typename _Tp>
53 class polymorphic_allocator;
55 template <typename _Alloc>
56 class __resource_adaptor_imp;
58 template <typename _Alloc>
59 using resource_adaptor = __resource_adaptor_imp<
60 typename allocator_traits<_Alloc>::template rebind_alloc<char>>;
62 template <typename _Tp>
63 struct __uses_allocator_construction_helper;
65 // Global memory resources
66 memory_resource* new_delete_resource() noexcept;
67 memory_resource* null_memory_resource() noexcept;
69 // The default memory resource
70 memory_resource* get_default_resource() noexcept;
71 memory_resource* set_default_resource(memory_resource* __r) noexcept;
73 // Standard memory resources
75 // 8.5 Class memory_resource
79 static constexpr size_t _S_max_align = alignof(max_align_t);
82 virtual ~memory_resource() { }
85 allocate(size_t __bytes, size_t __alignment = _S_max_align)
86 { return do_allocate(__bytes, __alignment); }
89 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align)
90 { return do_deallocate(__p, __bytes, __alignment); }
93 is_equal(const memory_resource& __other) const noexcept
94 { return do_is_equal(__other); }
98 do_allocate(size_t __bytes, size_t __alignment) = 0;
101 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0;
104 do_is_equal(const memory_resource& __other) const noexcept = 0;
108 operator==(const memory_resource& __a,
109 const memory_resource& __b) noexcept
110 { return &__a == &__b || __a.is_equal(__b); }
113 operator!=(const memory_resource& __a,
114 const memory_resource& __b) noexcept
115 { return !(__a == __b); }
118 // 8.6 Class template polymorphic_allocator
120 class polymorphic_allocator
122 using __uses_alloc1_ = __uses_alloc1<memory_resource*>;
123 using __uses_alloc2_ = __uses_alloc2<memory_resource*>;
125 template<typename _Tp1, typename... _Args>
127 _M_construct(__uses_alloc0, _Tp1* __p, _Args&&... __args)
128 { ::new(__p) _Tp1(std::forward<_Args>(__args)...); }
130 template<typename _Tp1, typename... _Args>
132 _M_construct(__uses_alloc1_, _Tp1* __p, _Args&&... __args)
133 { ::new(__p) _Tp1(allocator_arg, this->resource(),
134 std::forward<_Args>(__args)...); }
136 template<typename _Tp1, typename... _Args>
138 _M_construct(__uses_alloc2_, _Tp1* __p, _Args&&... __args)
139 { ::new(__p) _Tp1(std::forward<_Args>(__args)...,
143 using value_type = _Tp;
145 polymorphic_allocator() noexcept
146 : _M_resource(get_default_resource())
149 polymorphic_allocator(memory_resource* __r)
151 { _GLIBCXX_DEBUG_ASSERT(__r); }
153 polymorphic_allocator(const polymorphic_allocator& __other) = default;
155 template <typename _Up>
156 polymorphic_allocator(const polymorphic_allocator<_Up>&
158 : _M_resource(__other.resource())
161 polymorphic_allocator&
162 operator=(const polymorphic_allocator& __rhs) = default;
164 _Tp* allocate(size_t __n)
165 { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
168 void deallocate(_Tp* __p, size_t __n)
169 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
171 template <typename _Tp1, typename... _Args> //used here
172 void construct(_Tp1* __p, _Args&&... __args)
174 memory_resource* const __resource = this->resource();
176 = __use_alloc<_Tp1, memory_resource*, _Args...>(__resource);
177 _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
180 // Specializations for pair using piecewise construction
181 template <typename _Tp1, typename _Tp2,
182 typename... _Args1, typename... _Args2>
183 void construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
184 tuple<_Args1...> __x,
185 tuple<_Args2...> __y)
187 memory_resource* const __resource = this->resource();
189 __use_alloc<_Tp1, memory_resource*, _Args1...>(__resource);
191 __use_alloc<_Tp2, memory_resource*, _Args2...>(__resource);
193 ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct,
194 _M_construct_p(__x_use_tag, __x),
195 _M_construct_p(__y_use_tag, __y));
198 template <typename _Tp1, typename _Tp2>
199 void construct(pair<_Tp1,_Tp2>* __p)
200 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
202 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
203 void construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y)
204 { this->construct(__p, piecewise_construct,
205 forward_as_tuple(std::forward<_Up>(__x)),
206 forward_as_tuple(std::forward<_Vp>(__y))); }
208 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
209 void construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
210 { this->construct(__p, piecewise_construct, forward_as_tuple(__pr.first),
211 forward_as_tuple(__pr.second)); }
213 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
214 void construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr)
215 { this->construct(__p, piecewise_construct,
216 forward_as_tuple(std::forward<_Up>(__pr.first)),
217 forward_as_tuple(std::forward<_Vp>(__pr.second))); }
219 template <typename _Up>
220 void destroy(_Up* __p)
223 // Return a default-constructed allocator (no allocator propagation)
224 polymorphic_allocator select_on_container_copy_construction() const
225 { return polymorphic_allocator(); }
227 memory_resource* resource() const
228 { return _M_resource; }
231 template<typename _Tuple>
233 _M_construct_p(__uses_alloc0, _Tuple& __t)
234 { return std::move(__t); }
236 template<typename... _Args>
238 _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t)
239 { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)),
242 template<typename... _Args>
244 _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t)
245 { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); }
247 memory_resource* _M_resource;
250 template <class _Tp1, class _Tp2>
251 bool operator==(const polymorphic_allocator<_Tp1>& __a,
252 const polymorphic_allocator<_Tp2>& __b) noexcept
253 { return *__a.resource() == *__b.resource(); }
255 template <class _Tp1, class _Tp2>
256 bool operator!=(const polymorphic_allocator<_Tp1>& __a,
257 const polymorphic_allocator<_Tp2>& __b) noexcept
258 { return !(__a == __b); }
260 // 8.7.1 __resource_adaptor_imp
261 template <typename _Alloc>
262 class __resource_adaptor_imp : public memory_resource
264 static_assert(is_same<char,
265 typename allocator_traits<_Alloc>::value_type>::value,
266 "Allocator's value_type is char");
267 static_assert(is_same<char*,
268 typename allocator_traits<_Alloc>::pointer>::value,
269 "Allocator's pointer type is value_type*");
270 static_assert(is_same<const char*,
271 typename allocator_traits<_Alloc>::const_pointer>::value,
272 "Allocator's const_pointer type is value_type const*");
273 static_assert(is_same<void*,
274 typename allocator_traits<_Alloc>::void_pointer>::value,
275 "Allocator's void_pointer type is void*");
276 static_assert(is_same<const void*,
277 typename allocator_traits<_Alloc>::const_void_pointer>::value,
278 "Allocator's const_void_pointer type is void const*");
281 using allocator_type = _Alloc;
283 __resource_adaptor_imp() = default;
284 __resource_adaptor_imp(const __resource_adaptor_imp&) = default;
285 __resource_adaptor_imp(__resource_adaptor_imp&&) = default;
287 explicit __resource_adaptor_imp(const _Alloc& __a2)
291 explicit __resource_adaptor_imp(_Alloc&& __a2)
292 : _M_alloc(std::move(__a2))
295 __resource_adaptor_imp&
296 operator=(const __resource_adaptor_imp&) = default;
298 allocator_type get_allocator() const noexcept { return _M_alloc; }
302 do_allocate(size_t __bytes, size_t __alignment)
304 using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
305 size_t __new_size = _S_aligned_size(__bytes,
306 _S_supported(__alignment) ?
307 __alignment : _S_max_align);
308 return _Aligned_alloc(_M_alloc).allocate(__new_size);
312 do_deallocate(void* __p, size_t __bytes, size_t __alignment)
314 using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
315 size_t __new_size = _S_aligned_size(__bytes,
316 _S_supported(__alignment) ?
317 __alignment : _S_max_align);
318 using _Ptr = typename allocator_traits<_Aligned_alloc>::pointer;
319 _Aligned_alloc(_M_alloc).deallocate(static_cast<_Ptr>(__p),
324 do_is_equal(const memory_resource& __other) const noexcept
326 auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other);
327 return __p ? (_M_alloc == __p->_M_alloc) : false;
331 // Calculate Aligned Size
332 // Returns a size that is larger than or equal to __size and divisible
333 // by __alignment, where __alignment is required to be a power of 2.
335 _S_aligned_size(size_t __size, size_t __alignment)
336 { return ((__size - 1)|(__alignment - 1)) + 1; }
338 // Determine whether alignment meets one of those preconditions:
340 // 2. Is power of two
342 _S_supported (size_t __x)
343 { return ((__x != 0) && !(__x & (__x - 1))); }
348 // Global memory resources
350 inline memory_resource*
351 new_delete_resource() noexcept
353 using type = resource_adaptor<std::allocator<char>>;
354 alignas(type) static unsigned char __buf[sizeof(type)];
355 static type* __r = new(__buf) type;
359 inline memory_resource*
360 null_memory_resource() noexcept
362 class type final : public memory_resource
365 do_allocate(size_t, size_t) override
366 { std::__throw_bad_alloc(); }
369 do_deallocate(void*, size_t, size_t) noexcept override
373 do_is_equal(const memory_resource& __other) const noexcept override
374 { return this == &__other; }
377 alignas(type) static unsigned char __buf[sizeof(type)];
378 static type* __r = new(__buf) type;
382 // The default memory resource
384 inline std::atomic<memory_resource*>&
385 __get_default_resource()
387 using type = atomic<memory_resource*>;
388 alignas(type) static unsigned char __buf[sizeof(type)];
389 static type* __r = new(__buf) type(new_delete_resource());
393 inline memory_resource*
394 get_default_resource() noexcept
395 { return __get_default_resource().load(); }
397 inline memory_resource*
398 set_default_resource(memory_resource* __r) noexcept
401 __r = new_delete_resource();
402 return __get_default_resource().exchange(__r);
405 } // namespace fundamentals_v2
406 } // namespace experimental
408 _GLIBCXX_END_NAMESPACE_VERSION
411 #endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE