libstdc++-v3/include/experimental/memory_resource

   1 // <experimental/memory_resource> -*- C++ -*-
   2
   3 // Copyright (C) 2015-2016 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 <bits/alloc_traits.h>
  37 #include <experimental/bits/lfts_config.h>
  38
  39 namespace std {
  40 namespace experimental {
  41 inline namespace fundamentals_v2 {
  42 namespace pmr {
  43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  44
  45 #define __cpp_lib_experimental_memory_resources 201402L
  46
  47   class memory_resource;
  48
  49   template <typename _Tp>
  50     class polymorphic_allocator;
  51
  52   template <typename _Alloc>
  53     class __resource_adaptor_imp;
  54
  55   template <typename _Alloc>
  56     using resource_adaptor = __resource_adaptor_imp<
  57       typename allocator_traits<_Alloc>::template rebind_alloc<char>>;
  58
  59   template <typename _Tp>
  60     struct __uses_allocator_construction_helper;
  61
  62   // Global memory resources
  63   memory_resource* new_delete_resource() noexcept;
  64   memory_resource* null_memory_resource() noexcept;
  65
  66   // The default memory resource
  67   memory_resource* get_default_resource() noexcept;
  68   memory_resource* set_default_resource(memory_resource* __r) noexcept;
  69
  70   // Standard memory resources
  71
  72   // 8.5 Class memory_resource
  73   class memory_resource
  74   {
  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           auto __use_tag = __use_alloc<_Tp1, memory_resource*,
 171                _Args...>(this->resource());
 172           _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
 173         }
 174
 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)
 181         {
 182           auto __x_use_tag =
 183             __use_alloc<_Tp1, memory_resource*, _Args1...>(this->resource());
 184           auto __y_use_tag =
 185             __use_alloc<_Tp2, memory_resource*, _Args2...>(this->resource());
 186
 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));
 190         }
 191
 192       template <typename _Tp1, typename _Tp2>
 193         void construct(pair<_Tp1,_Tp2>* __p)
 194         { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
 195
 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))); }
 201
 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)); }
 206
 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))); }
 212
 213       template <typename _Up>
 214         void destroy(_Up* __p)
 215         { __p->~_Up(); }
 216
 217       // Return a default-constructed allocator (no allocator propagation)
 218       polymorphic_allocator select_on_container_copy_construction() const
 219       { return polymorphic_allocator(); }
 220
 221       memory_resource* resource() const
 222       { return _M_resource; }
 223
 224     private:
 225       template<typename _Tuple>
 226         _Tuple&&
 227         _M_construct_p(__uses_alloc0, _Tuple& __t)
 228         { return std::move(__t); }
 229
 230       template<typename... _Args>
 231         decltype(auto)
 232         _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t)
 233         { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)),
 234                            std::move(__t)); }
 235
 236       template<typename... _Args>
 237         decltype(auto)
 238         _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t)
 239         { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); }
 240
 241       memory_resource* _M_resource;
 242     };
 243
 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(); }
 248
 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); }
 253
 254   // 8.7.1 __resource_adaptor_imp
 255   template <typename _Alloc>
 256     class __resource_adaptor_imp : public memory_resource
 257     {
 258     public:
 259       using allocator_type = _Alloc;
 260
 261       __resource_adaptor_imp() = default;
 262       __resource_adaptor_imp(const __resource_adaptor_imp&) = default;
 263       __resource_adaptor_imp(__resource_adaptor_imp&&) = default;
 264
 265       explicit __resource_adaptor_imp(const _Alloc& __a2)
 266       : _M_alloc(__a2)
 267       { }
 268
 269       explicit __resource_adaptor_imp(_Alloc&& __a2)
 270       : _M_alloc(std::move(__a2))
 271       { }
 272
 273       __resource_adaptor_imp&
 274       operator=(const __resource_adaptor_imp&) = default;
 275
 276       allocator_type get_allocator() const { return _M_alloc; }
 277
 278     protected:
 279       virtual void*
 280       do_allocate(size_t __bytes, size_t __alignment)
 281       {
 282         using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
 283         size_t __new_size = _S_aligned_size(__bytes,
 284                                             _S_supported(__alignment) ?
 285                                             __alignment : _S_max_align);
 286         return _Aligned_alloc(_M_alloc).allocate(__new_size);
 287       }
 288
 289       virtual void
 290       do_deallocate(void* __p, size_t __bytes, size_t __alignment)
 291       {
 292         using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
 293         size_t __new_size = _S_aligned_size(__bytes,
 294                                             _S_supported(__alignment) ?
 295                                             __alignment : _S_max_align);
 296         using _Ptr = typename allocator_traits<_Aligned_alloc>::pointer;
 297         _Aligned_alloc(_M_alloc).deallocate(static_cast<_Ptr>(__p),
 298                                             __new_size);
 299       }
 300
 301       virtual bool
 302       do_is_equal(const memory_resource& __other) const noexcept
 303       {
 304         auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other);
 305         return __p ? (_M_alloc == __p->_M_alloc) : false;
 306       }
 307
 308     private:
 309       // Calculate Aligned Size
 310       // Returns a size that is larger than or equal to __size and divisible
 311       // by __alignment, where __alignment is required to be the power of 2.
 312       static size_t
 313       _S_aligned_size(size_t __size, size_t __alignment)
 314       { return ((__size - 1)|(__alignment - 1)) + 1; }
 315
 316       // Determine whether alignment meets one of those preconditions:
 317       // 1. Equals to Zero
 318       // 2. Is power of two
 319       static bool
 320       _S_supported (size_t __x)
 321       { return ((__x != 0) && !(__x & (__x - 1))); }
 322
 323       _Alloc _M_alloc;
 324     };
 325
 326   // Global memory resources
 327   inline std::atomic<memory_resource*>&
 328   __get_default_resource()
 329   {
 330     static atomic<memory_resource*> _S_default_resource(new_delete_resource());
 331     return _S_default_resource;
 332   }
 333
 334   inline memory_resource*
 335   new_delete_resource() noexcept
 336   {
 337     static resource_adaptor<std::allocator<char>> __r;
 338     return static_cast<memory_resource*>(&__r);
 339   }
 340
 341   template <typename _Alloc>
 342     class __null_memory_resource : private memory_resource
 343     {
 344     protected:
 345       void*
 346       do_allocate(size_t, size_t)
 347       { std::__throw_bad_alloc(); }
 348
 349       void
 350       do_deallocate(void*, size_t, size_t) noexcept
 351       { }
 352
 353       bool
 354       do_is_equal(const memory_resource& __other) const noexcept
 355       { return this == &__other; }
 356
 357       friend memory_resource* null_memory_resource() noexcept;
 358     };
 359
 360   inline memory_resource*
 361   null_memory_resource() noexcept
 362   {
 363     static __null_memory_resource<void> __r;
 364     return static_cast<memory_resource*>(&__r);
 365   }
 366
 367   // The default memory resource
 368   inline memory_resource*
 369   get_default_resource() noexcept
 370   { return __get_default_resource().load(); }
 371
 372   inline memory_resource*
 373   set_default_resource(memory_resource* __r) noexcept
 374   {
 375     if (__r == nullptr)
 376       __r = new_delete_resource();
 377     return __get_default_resource().exchange(__r);
 378   }
 379
 380 _GLIBCXX_END_NAMESPACE_VERSION
 381 } // namespace pmr
 382 } // namespace fundamentals_v2
 383 } // namespace experimental
 384 } // namespace std
 385
 386 #endif