1// <experimental/memory_resource> -*- C++ -*-
2
3// Copyright (C) 2015-2017 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 */
28
29#ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE
30#define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1
31
32#include <memory>
33#include <new>
34#include <atomic>
35#include <cstddef>
36#include <experimental/bits/lfts_config.h>
37
38namespace std {
39namespace experimental {
40inline namespace fundamentals_v2 {
41namespace pmr {
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
43
44#define __cpp_lib_experimental_memory_resources 201402L
45
46  class memory_resource;
47
48  template <typename _Tp>
49    class polymorphic_allocator;
50
51  template <typename _Alloc>
52    class __resource_adaptor_imp;
53
54  template <typename _Alloc>
55    using resource_adaptor = __resource_adaptor_imp<
56      typename allocator_traits<_Alloc>::template rebind_alloc<char>>;
57
58  template <typename _Tp>
59    struct __uses_allocator_construction_helper;
60
61  // Global memory resources
62  memory_resource* new_delete_resource() noexcept;
63  memory_resource* null_memory_resource() noexcept;
64
65  // The default memory resource
66  memory_resource* get_default_resource() noexcept;
67  memory_resource* set_default_resource(memory_resource* __r) noexcept;
68
69  // Standard memory resources
70
71  // 8.5 Class memory_resource
72  class memory_resource
73  {
74  protected:
75    static constexpr size_t _S_max_align = alignof(max_align_t);
76
77  public:
78    virtual ~memory_resource() { }
79
80    void*
81    allocate(size_t __bytes, size_t __alignment = _S_max_align)
82    { return do_allocate(__bytes, __alignment); }
83
84    void
85    deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align)
86    { return do_deallocate(__p, __bytes, __alignment); }
87
88    bool
89    is_equal(const memory_resource& __other) const noexcept
90    { return do_is_equal(__other); }
91
92  protected:
93    virtual void*
94    do_allocate(size_t __bytes, size_t __alignment) = 0;
95
96    virtual void
97    do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0;
98
99    virtual bool
100    do_is_equal(const memory_resource& __other) const noexcept = 0;
101  };
102
103  inline bool
104  operator==(const memory_resource& __a,
105	     const memory_resource& __b) noexcept
106  { return &__a == &__b || __a.is_equal(__b); }
107
108  inline bool
109  operator!=(const memory_resource& __a,
110	     const memory_resource& __b) noexcept
111  { return !(__a == __b); }
112
113
114  // 8.6 Class template polymorphic_allocator
115  template <class _Tp>
116    class polymorphic_allocator
117    {
118      using __uses_alloc1_ = __uses_alloc1<memory_resource*>;
119      using __uses_alloc2_ = __uses_alloc2<memory_resource*>;
120
121      template<typename _Tp1, typename... _Args>
122	void
123	_M_construct(__uses_alloc0, _Tp1* __p, _Args&&... __args)
124	{ ::new(__p) _Tp1(std::forward<_Args>(__args)...); }
125
126      template<typename _Tp1, typename... _Args>
127	void
128	_M_construct(__uses_alloc1_, _Tp1* __p, _Args&&...  __args)
129	{ ::new(__p) _Tp1(allocator_arg, this->resource(),
130			  std::forward<_Args>(__args)...); }
131
132      template<typename _Tp1, typename... _Args>
133	void
134	_M_construct(__uses_alloc2_, _Tp1* __p, _Args&&...  __args)
135	{ ::new(__p) _Tp1(std::forward<_Args>(__args)...,
136			  this->resource()); }
137
138    public:
139      using value_type = _Tp;
140
141      polymorphic_allocator() noexcept
142      : _M_resource(get_default_resource())
143      { }
144
145      polymorphic_allocator(memory_resource* __r)
146      : _M_resource(__r)
147      { _GLIBCXX_DEBUG_ASSERT(__r); }
148
149      polymorphic_allocator(const polymorphic_allocator& __other) = default;
150
151      template <typename _Up>
152	polymorphic_allocator(const polymorphic_allocator<_Up>&
153			      __other) noexcept
154	: _M_resource(__other.resource())
155	{ }
156
157      polymorphic_allocator&
158	operator=(const polymorphic_allocator& __rhs) = default;
159
160      _Tp* allocate(size_t __n)
161      { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
162						       alignof(_Tp))); }
163
164      void deallocate(_Tp* __p, size_t __n)
165      { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
166
167      template <typename _Tp1, typename... _Args> //used here
168	void construct(_Tp1* __p, _Args&&... __args)
169	{
170	  memory_resource* const __resource = this->resource();
171	  auto __use_tag
172	    = __use_alloc<_Tp1, memory_resource*, _Args...>(__resource);
173	  _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
174	}
175
176      // Specializations for pair using piecewise construction
177      template <typename _Tp1, typename _Tp2,
178	       typename... _Args1, typename... _Args2>
179	void construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
180		       tuple<_Args1...> __x,
181		       tuple<_Args2...> __y)
182	{
183	  memory_resource* const __resource = this->resource();
184	  auto __x_use_tag =
185	    __use_alloc<_Tp1, memory_resource*, _Args1...>(__resource);
186	  auto __y_use_tag =
187	    __use_alloc<_Tp2, memory_resource*, _Args2...>(__resource);
188
189	  ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct,
190					   _M_construct_p(__x_use_tag, __x),
191					   _M_construct_p(__y_use_tag, __y));
192	}
193
194      template <typename _Tp1, typename _Tp2>
195	void construct(pair<_Tp1,_Tp2>* __p)
196	{ this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
197
198      template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
199	void construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y)
200	{ this->construct(__p, piecewise_construct,
201			  forward_as_tuple(std::forward<_Up>(__x)),
202			  forward_as_tuple(std::forward<_Vp>(__y))); }
203
204      template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
205	void construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
206	{ this->construct(__p, piecewise_construct, forward_as_tuple(__pr.first),
207			  forward_as_tuple(__pr.second)); }
208
209      template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
210	void construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr)
211	{ this->construct(__p, piecewise_construct,
212			  forward_as_tuple(std::forward<_Up>(__pr.first)),
213			  forward_as_tuple(std::forward<_Vp>(__pr.second))); }
214
215      template <typename _Up>
216	void destroy(_Up* __p)
217	{ __p->~_Up(); }
218
219      // Return a default-constructed allocator (no allocator propagation)
220      polymorphic_allocator select_on_container_copy_construction() const
221      { return polymorphic_allocator(); }
222
223      memory_resource* resource() const
224      { return _M_resource; }
225
226    private:
227      template<typename _Tuple>
228	_Tuple&&
229	_M_construct_p(__uses_alloc0, _Tuple& __t)
230	{ return std::move(__t); }
231
232      template<typename... _Args>
233	decltype(auto)
234	_M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t)
235	{ return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)),
236			   std::move(__t)); }
237
238      template<typename... _Args>
239	decltype(auto)
240	_M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t)
241	{ return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); }
242
243      memory_resource* _M_resource;
244    };
245
246  template <class _Tp1, class _Tp2>
247    bool operator==(const polymorphic_allocator<_Tp1>& __a,
248		    const polymorphic_allocator<_Tp2>& __b) noexcept
249    { return *__a.resource() == *__b.resource(); }
250
251  template <class _Tp1, class _Tp2>
252    bool operator!=(const polymorphic_allocator<_Tp1>& __a,
253		    const polymorphic_allocator<_Tp2>& __b) noexcept
254    { return !(__a == __b); }
255
256  // 8.7.1 __resource_adaptor_imp
257  template <typename _Alloc>
258    class __resource_adaptor_imp : public memory_resource
259    {
260      static_assert(is_same<char,
261	  typename allocator_traits<_Alloc>::value_type>::value,
262	  "Allocator's value_type is char");
263      static_assert(is_same<char*,
264	  typename allocator_traits<_Alloc>::pointer>::value,
265	  "Allocator's pointer type is value_type*");
266      static_assert(is_same<const char*,
267	  typename allocator_traits<_Alloc>::const_pointer>::value,
268	  "Allocator's const_pointer type is value_type const*");
269      static_assert(is_same<void*,
270	  typename allocator_traits<_Alloc>::void_pointer>::value,
271	  "Allocator's void_pointer type is void*");
272      static_assert(is_same<const void*,
273	  typename allocator_traits<_Alloc>::const_void_pointer>::value,
274	  "Allocator's const_void_pointer type is void const*");
275
276    public:
277      using allocator_type = _Alloc;
278
279      __resource_adaptor_imp() = default;
280      __resource_adaptor_imp(const __resource_adaptor_imp&) = default;
281      __resource_adaptor_imp(__resource_adaptor_imp&&) = default;
282
283      explicit __resource_adaptor_imp(const _Alloc& __a2)
284      : _M_alloc(__a2)
285      { }
286
287      explicit __resource_adaptor_imp(_Alloc&& __a2)
288      : _M_alloc(std::move(__a2))
289      { }
290
291      __resource_adaptor_imp&
292      operator=(const __resource_adaptor_imp&) = default;
293
294      allocator_type get_allocator() const noexcept { return _M_alloc; }
295
296    protected:
297      virtual void*
298      do_allocate(size_t __bytes, size_t __alignment)
299      {
300	using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
301	size_t __new_size = _S_aligned_size(__bytes,
302					    _S_supported(__alignment) ?
303					    __alignment : _S_max_align);
304	return _Aligned_alloc(_M_alloc).allocate(__new_size);
305      }
306
307      virtual void
308      do_deallocate(void* __p, size_t __bytes, size_t __alignment)
309      {
310	using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
311	size_t __new_size = _S_aligned_size(__bytes,
312					    _S_supported(__alignment) ?
313					    __alignment : _S_max_align);
314	using _Ptr = typename allocator_traits<_Aligned_alloc>::pointer;
315	_Aligned_alloc(_M_alloc).deallocate(static_cast<_Ptr>(__p),
316					    __new_size);
317      }
318
319      virtual bool
320      do_is_equal(const memory_resource& __other) const noexcept
321      {
322	auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other);
323	return __p ? (_M_alloc == __p->_M_alloc) : false;
324      }
325
326    private:
327      // Calculate Aligned Size
328      // Returns a size that is larger than or equal to __size and divisible
329      // by __alignment, where __alignment is required to be a power of 2.
330      static size_t
331      _S_aligned_size(size_t __size, size_t __alignment)
332      { return ((__size - 1)|(__alignment - 1)) + 1; }
333
334      // Determine whether alignment meets one of those preconditions:
335      // 1. Equal to Zero
336      // 2. Is power of two
337      static bool
338      _S_supported (size_t __x)
339      { return ((__x != 0) && !(__x & (__x - 1))); }
340
341      _Alloc _M_alloc;
342    };
343
344  // Global memory resources
345
346  inline memory_resource*
347  new_delete_resource() noexcept
348  {
349    using type = resource_adaptor<std::allocator<char>>;
350    alignas(type) static unsigned char __buf[sizeof(type)];
351    static type* __r = new(__buf) type;
352    return __r;
353  }
354
355  inline memory_resource*
356  null_memory_resource() noexcept
357  {
358    class type final : public memory_resource
359    {
360      void*
361      do_allocate(size_t, size_t) override
362      { std::__throw_bad_alloc(); }
363
364      void
365      do_deallocate(void*, size_t, size_t) noexcept override
366      { }
367
368      bool
369      do_is_equal(const memory_resource& __other) const noexcept override
370      { return this == &__other; }
371    };
372
373    alignas(type) static unsigned char __buf[sizeof(type)];
374    static type* __r = new(__buf) type;
375    return __r;
376  }
377
378  // The default memory resource
379
380  inline std::atomic<memory_resource*>&
381  __get_default_resource()
382  {
383    using type = atomic<memory_resource*>;
384    alignas(type) static unsigned char __buf[sizeof(type)];
385    static type* __r = new(__buf) type(new_delete_resource());
386    return *__r;
387  }
388
389  inline memory_resource*
390  get_default_resource() noexcept
391  { return __get_default_resource().load(); }
392
393  inline memory_resource*
394  set_default_resource(memory_resource* __r) noexcept
395  {
396    if (__r == nullptr)
397      __r = new_delete_resource();
398    return __get_default_resource().exchange(__r);
399  }
400
401_GLIBCXX_END_NAMESPACE_VERSION
402} // namespace pmr
403} // namespace fundamentals_v2
404} // namespace experimental
405} // namespace std
406
407#endif
408