libstdc++-v3/include/experimental/memory_resource

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