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// <experimental/memory_resource> -*- C++ -*- |
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|
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// Copyright (C) 2015-2021 Free Software Foundation, Inc. |
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// |
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// This file is part of the GNU ISO C++ Library. This library is free |
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// software; you can redistribute it and/or modify it under the |
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// terms of the GNU General Public License as published by the |
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// Free Software Foundation; either version 3, or (at your option) |
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// any later version. |
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|
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// This library is distributed in the hope that it will be useful, |
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// but WITHOUT ANY WARRANTY; without even the implied warranty of |
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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// GNU General Public License for more details. |
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|
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// Under Section 7 of GPL version 3, you are granted additional |
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// permissions described in the GCC Runtime Library Exception, version |
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// 3.1, as published by the Free Software Foundation. |
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|
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// You should have received a copy of the GNU General Public License and |
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// a copy of the GCC Runtime Library Exception along with this program; |
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
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// <http://www.gnu.org/licenses/>. |
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|
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/** @file experimental/memory_resource |
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* This is a TS C++ Library header. |
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* @ingroup libfund-ts |
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*/ |
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|
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#ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE |
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#define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1 |
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|
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#pragma GCC system_header |
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|
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#if __cplusplus >= 201402L |
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|
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#include <memory> // align, uses_allocator, __uses_alloc |
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#include <experimental/utility> // pair, experimental::erased_type |
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#include <tuple> // tuple, forward_as_tuple |
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#include <atomic> // atomic |
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#include <new> // placement new |
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#include <cstddef> // max_align_t |
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#include <ext/new_allocator.h> |
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#include <debug/assertions.h> |
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|
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/// @cond |
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namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) |
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{ |
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_GLIBCXX_BEGIN_NAMESPACE_VERSION |
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template<typename _Tp> class malloc_allocator; |
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_GLIBCXX_END_NAMESPACE_VERSION |
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} // namespace __gnu_cxx |
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/// @endcond |
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|
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namespace std { |
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_GLIBCXX_BEGIN_NAMESPACE_VERSION |
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|
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namespace experimental { |
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inline namespace fundamentals_v2 { |
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namespace pmr { |
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#define __cpp_lib_experimental_memory_resources 201402L |
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|
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// Standard memory resources |
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|
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// 8.5 Class memory_resource |
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class memory_resource; |
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|
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// 8.6 Class template polymorphic_allocator |
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template<typename _Tp> |
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class polymorphic_allocator; |
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|
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template<typename _Alloc, typename _Resource = memory_resource> |
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class __resource_adaptor_imp; |
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|
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// 8.7 Alias template resource_adaptor |
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template<typename _Alloc> |
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using resource_adaptor = __resource_adaptor_imp< |
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typename allocator_traits<_Alloc>::template rebind_alloc<char>>; |
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|
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// 8.8 Global memory resources |
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memory_resource* new_delete_resource() noexcept; |
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memory_resource* null_memory_resource() noexcept; |
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memory_resource* get_default_resource() noexcept; |
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memory_resource* set_default_resource(memory_resource* __r) noexcept; |
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|
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// TODO 8.9 Pool resource classes |
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|
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class memory_resource |
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{ |
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static constexpr size_t _S_max_align = alignof(max_align_t); |
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|
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public: |
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memory_resource() = default; |
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memory_resource(const memory_resource&) = default; |
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virtual ~memory_resource() = default; |
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|
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memory_resource& operator=(const memory_resource&) = default; |
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|
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_GLIBCXX_NODISCARD void* |
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allocate(size_t __bytes, size_t __alignment = _S_max_align) |
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{ return do_allocate(__bytes, __alignment); } |
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|
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void |
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deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align) |
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{ return do_deallocate(__p, __bytes, __alignment); } |
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|
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bool |
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is_equal(const memory_resource& __other) const noexcept |
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{ return do_is_equal(__other); } |
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|
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protected: |
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virtual void* |
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do_allocate(size_t __bytes, size_t __alignment) = 0; |
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|
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virtual void |
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do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0; |
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|
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virtual bool |
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do_is_equal(const memory_resource& __other) const noexcept = 0; |
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}; |
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|
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inline bool |
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operator==(const memory_resource& __a, const memory_resource& __b) noexcept |
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{ return &__a == &__b || __a.is_equal(__b); } |
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|
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inline bool |
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operator!=(const memory_resource& __a, const memory_resource& __b) noexcept |
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{ return !(__a == __b); } |
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|
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|
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template<typename _Tp> |
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class polymorphic_allocator |
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{ |
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public: |
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using value_type = _Tp; |
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|
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polymorphic_allocator() noexcept |
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: _M_resource(get_default_resource()) |
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{ } |
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|
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polymorphic_allocator(memory_resource* __r) |
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: _M_resource(__r) |
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{ _GLIBCXX_DEBUG_ASSERT(__r); } |
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|
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polymorphic_allocator(const polymorphic_allocator& __other) = default; |
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|
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template <typename _Up> |
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polymorphic_allocator(const polymorphic_allocator<_Up>& |
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__other) noexcept |
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: _M_resource(__other.resource()) |
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{ } |
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|
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polymorphic_allocator& |
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operator=(const polymorphic_allocator& __rhs) = default; |
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|
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_GLIBCXX_NODISCARD _Tp* allocate(size_t __n) |
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{ return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp), |
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alignof(_Tp))); } |
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|
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void |
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deallocate(_Tp* __p, size_t __n) |
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{ _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); } |
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|
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template <typename _Tp1, typename... _Args> //used here |
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void |
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construct(_Tp1* __p, _Args&&... __args) |
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{ |
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std::__uses_allocator_construct(this->resource(), __p, |
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std::forward<_Args>(__args)...); |
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} |
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|
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// Specializations for pair using piecewise construction |
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template <typename _Tp1, typename _Tp2, |
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typename... _Args1, typename... _Args2> |
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void |
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construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t, |
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tuple<_Args1...> __x, tuple<_Args2...> __y) |
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{ |
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memory_resource* const __resource = this->resource(); |
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auto __x_use_tag = |
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std::__use_alloc<_Tp1, memory_resource*, _Args1...>(__resource); |
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auto __y_use_tag = |
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std::__use_alloc<_Tp2, memory_resource*, _Args2...>(__resource); |
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|
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::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct, |
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_M_construct_p(__x_use_tag, __x), |
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_M_construct_p(__y_use_tag, __y)); |
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} |
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|
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template <typename _Tp1, typename _Tp2> |
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void |
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construct(pair<_Tp1,_Tp2>* __p) |
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{ this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); } |
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|
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template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> |
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void |
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construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y) |
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{ |
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this->construct(__p, piecewise_construct, |
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std::forward_as_tuple(std::forward<_Up>(__x)), |
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std::forward_as_tuple(std::forward<_Vp>(__y))); |
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} |
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|
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template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> |
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void |
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construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr) |
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{ |
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this->construct(__p, piecewise_construct, |
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std::forward_as_tuple(__pr.first), |
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std::forward_as_tuple(__pr.second)); |
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} |
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|
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template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> |
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void |
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construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr) |
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{ |
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this->construct(__p, piecewise_construct, |
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std::forward_as_tuple(std::forward<_Up>(__pr.first)), |
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std::forward_as_tuple(std::forward<_Vp>(__pr.second))); |
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} |
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|
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template <typename _Up> |
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void |
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destroy(_Up* __p) |
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{ __p->~_Up(); } |
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|
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// Return a default-constructed allocator (no allocator propagation) |
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polymorphic_allocator |
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select_on_container_copy_construction() const |
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{ return polymorphic_allocator(); } |
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|
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memory_resource* resource() const { return _M_resource; } |
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|
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private: |
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using __uses_alloc1_ = __uses_alloc1<memory_resource*>; |
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using __uses_alloc2_ = __uses_alloc2<memory_resource*>; |
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|
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template<typename _Tuple> |
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_Tuple&& |
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_M_construct_p(__uses_alloc0, _Tuple& __t) |
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{ return std::move(__t); } |
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|
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template<typename... _Args> |
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decltype(auto) |
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_M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t) |
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{ return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)), |
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std::move(__t)); } |
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|
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template<typename... _Args> |
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decltype(auto) |
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_M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t) |
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{ return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); } |
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|
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memory_resource* _M_resource; |
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}; |
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|
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template <class _Tp1, class _Tp2> |
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bool |
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operator==(const polymorphic_allocator<_Tp1>& __a, |
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const polymorphic_allocator<_Tp2>& __b) noexcept |
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{ return *__a.resource() == *__b.resource(); } |
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|
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template <class _Tp1, class _Tp2> |
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bool |
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operator!=(const polymorphic_allocator<_Tp1>& __a, |
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const polymorphic_allocator<_Tp2>& __b) noexcept |
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{ return !(__a == __b); } |
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|
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|
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/// @cond undocumented |
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class __resource_adaptor_common |
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{ |
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template<typename, typename> friend class __resource_adaptor_imp; |
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|
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struct _AlignMgr |
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{ |
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_AlignMgr(size_t __nbytes, size_t __align) |
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: _M_nbytes(__nbytes), _M_align(__align) |
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{ } |
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|
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// Total size that needs to be allocated. |
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size_t |
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_M_alloc_size() const { return _M_buf_size() + _M_token_size(); } |
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|
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void* |
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_M_adjust(void* __ptr) const |
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{ |
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const auto __orig_ptr = static_cast<char*>(__ptr); |
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size_t __space = _M_buf_size(); |
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// Align the pointer within the buffer: |
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std::align(_M_align, _M_nbytes, __ptr, __space); |
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const auto __aligned_ptr = static_cast<char*>(__ptr); |
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const auto __token_size = _M_token_size(); |
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// Store token immediately after the aligned block: |
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char* const __end = __aligned_ptr + _M_nbytes; |
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if (__token_size == 1) |
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_S_write<unsigned char>(__end, __aligned_ptr - __orig_ptr); |
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else if (__token_size == sizeof(short)) |
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_S_write<unsigned short>(__end, __aligned_ptr - __orig_ptr); |
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else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*)) |
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_S_write<unsigned int>(__end, __aligned_ptr - __orig_ptr); |
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else // (__token_size == sizeof(char*)) |
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// Just store the original pointer: |
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_S_write<char*>(__end, __orig_ptr); |
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return __aligned_ptr; |
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} |
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|
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char* |
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_M_unadjust(char* __ptr) const |
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{ |
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const char* const __end = __ptr + _M_nbytes; |
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char* __orig_ptr; |
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const auto __token_size = _M_token_size(); |
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// Read the token and restore the original pointer: |
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if (__token_size == 1) |
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__orig_ptr = __ptr - _S_read<unsigned char>(__end); |
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else if (__token_size == sizeof(short)) |
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__orig_ptr = __ptr - _S_read<unsigned short>(__end); |
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else if (__token_size == sizeof(int) |
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&& sizeof(int) < sizeof(char*)) |
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__orig_ptr = __ptr - _S_read<unsigned int>(__end); |
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else // (__token_size == sizeof(char*)) |
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__orig_ptr = _S_read<char*>(__end); |
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// The adjustment is always less than the requested alignment, |
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// so if that isn't true now then either the wrong size was passed |
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// to deallocate or the token was overwritten by a buffer overflow: |
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__glibcxx_assert(static_cast<size_t>(__ptr - __orig_ptr) < _M_align); |
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return __orig_ptr; |
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} |
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|
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private: |
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size_t _M_nbytes; |
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size_t _M_align; |
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|
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// Number of bytes needed to fit block of given size and alignment. |
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size_t |
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_M_buf_size() const { return _M_nbytes + _M_align - 1; } |
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|
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// Number of additional bytes needed to write the token. |
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int |
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_M_token_size() const |
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{ |
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if (_M_align <= (1ul << __CHAR_BIT__)) |
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return 1; |
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if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__))) |
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return sizeof(short); |
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if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__))) |
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return sizeof(int); |
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return sizeof(char*); |
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} |
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|
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template<typename _Tp> |
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static void |
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_S_write(void* __to, _Tp __val) |
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{ __builtin_memcpy(__to, &__val, sizeof(_Tp)); } |
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|
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template<typename _Tp> |
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static _Tp |
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_S_read(const void* __from) |
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{ |
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_Tp __val; |
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__builtin_memcpy(&__val, __from, sizeof(_Tp)); |
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return __val; |
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} |
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}; |
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}; |
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/// @endcond |
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|
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// 8.7.1 __resource_adaptor_imp |
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template<typename _Alloc, typename _Resource> |
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class __resource_adaptor_imp |
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: public _Resource, private __resource_adaptor_common |
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{ |
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using memory_resource = _Resource; |
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|
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static_assert(is_same<char, |
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typename allocator_traits<_Alloc>::value_type>::value, |
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"Allocator's value_type is char"); |
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static_assert(is_same<char*, |
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typename allocator_traits<_Alloc>::pointer>::value, |
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"Allocator's pointer type is value_type*"); |
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static_assert(is_same<const char*, |
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typename allocator_traits<_Alloc>::const_pointer>::value, |
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"Allocator's const_pointer type is value_type const*"); |
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static_assert(is_same<void*, |
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typename allocator_traits<_Alloc>::void_pointer>::value, |
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"Allocator's void_pointer type is void*"); |
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static_assert(is_same<const void*, |
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typename allocator_traits<_Alloc>::const_void_pointer>::value, |
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"Allocator's const_void_pointer type is void const*"); |
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|
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public: |
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using allocator_type = _Alloc; |
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|
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__resource_adaptor_imp() = default; |
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__resource_adaptor_imp(const __resource_adaptor_imp&) = default; |
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__resource_adaptor_imp(__resource_adaptor_imp&&) = default; |
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|
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explicit __resource_adaptor_imp(const _Alloc& __a2) |
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: _M_alloc(__a2) |
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{ } |
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|
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explicit __resource_adaptor_imp(_Alloc&& __a2) |
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: _M_alloc(std::move(__a2)) |
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{ } |
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|
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__resource_adaptor_imp& |
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operator=(const __resource_adaptor_imp&) = default; |
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|
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allocator_type get_allocator() const noexcept { return _M_alloc; } |
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|
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protected: |
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virtual void* |
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do_allocate(size_t __bytes, size_t __alignment) override |
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{ |
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// Cannot use max_align_t on 32-bit Solaris x86, see PR libstdc++/77691 |
| 417 |
#if ! ((defined __sun__ || defined __VXWORKS__) && defined __i386__) |
| 418 |
if (__alignment == alignof(max_align_t)) |
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return _M_allocate<alignof(max_align_t)>(__bytes); |
| 420 |
#endif |
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switch (__alignment) |
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{ |
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case 1: |
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return _M_alloc.allocate(__bytes); |
| 425 |
case 2: |
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return _M_allocate<2>(__bytes); |
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case 4: |
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return _M_allocate<4>(__bytes); |
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case 8: |
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return _M_allocate<8>(__bytes); |
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} |
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const _AlignMgr __mgr(__bytes, __alignment); |
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// Assume _M_alloc returns 1-byte aligned memory, so allocate enough |
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// space to fit a block of the right size and alignment, plus some |
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// extra bytes to store a token for retrieving the original pointer. |
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return __mgr._M_adjust(_M_alloc.allocate(__mgr._M_alloc_size())); |
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} |
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|
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virtual void |
| 440 |
do_deallocate(void* __ptr, size_t __bytes, size_t __alignment) noexcept |
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override |
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{ |
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#if ! ((defined __sun__ || defined __VXWORKS__) && defined __i386__) |
| 444 |
if (__alignment == alignof(max_align_t)) |
| 445 |
return (void) _M_deallocate<alignof(max_align_t)>(__ptr, __bytes); |
| 446 |
#endif |
| 447 |
switch (__alignment) |
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{ |
| 449 |
case 1: |
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return (void) _M_alloc.deallocate((char*)__ptr, __bytes); |
| 451 |
case 2: |
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return (void) _M_deallocate<2>(__ptr, __bytes); |
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case 4: |
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return (void) _M_deallocate<4>(__ptr, __bytes); |
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case 8: |
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return (void) _M_deallocate<8>(__ptr, __bytes); |
| 457 |
} |
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const _AlignMgr __mgr(__bytes, __alignment); |
| 459 |
// Use the stored token to retrieve the original pointer. |
| 460 |
_M_alloc.deallocate(__mgr._M_unadjust((char*)__ptr), |
| 461 |
__mgr._M_alloc_size()); |
| 462 |
} |
| 463 |
|
| 464 |
virtual bool |
| 465 |
do_is_equal(const memory_resource& __other) const noexcept override |
| 466 |
{ |
| 467 |
if (auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other)) |
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return _M_alloc == __p->_M_alloc; |
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return false; |
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} |
| 471 |
|
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private: |
| 473 |
template<size_t _Num> |
| 474 |
struct _Aligned_type { alignas(_Num) char __c[_Num]; }; |
| 475 |
|
| 476 |
// Rebind the allocator to the specified type and use it to allocate. |
| 477 |
template<size_t _Num, typename _Tp = _Aligned_type<_Num>> |
| 478 |
void* |
| 479 |
_M_allocate(size_t __bytes) |
| 480 |
{ |
| 481 |
typename allocator_traits<_Alloc>::template |
| 482 |
rebind_alloc<_Tp> __a2(_M_alloc); |
| 483 |
const size_t __n = (__bytes + _Num - 1) / _Num; |
| 484 |
return __a2.allocate(__n); |
| 485 |
} |
| 486 |
|
| 487 |
// Rebind the allocator to the specified type and use it to deallocate. |
| 488 |
template<size_t _Num, typename _Tp = _Aligned_type<_Num>> |
| 489 |
void |
| 490 |
_M_deallocate(void* __ptr, size_t __bytes) noexcept |
| 491 |
{ |
| 492 |
typename allocator_traits<_Alloc>::template |
| 493 |
rebind_alloc<_Tp> __a2(_M_alloc); |
| 494 |
const size_t __n = (__bytes + _Num - 1) / _Num; |
| 495 |
__a2.deallocate((_Tp*)__ptr, __n); |
| 496 |
} |
| 497 |
|
| 498 |
_Alloc _M_alloc{}; |
| 499 |
}; |
| 500 |
|
| 501 |
// Global memory resources |
| 502 |
|
| 503 |
inline memory_resource* |
| 504 |
new_delete_resource() noexcept |
| 505 |
{ |
| 506 |
using type = resource_adaptor<__gnu_cxx::new_allocator<char>>; |
| 507 |
alignas(type) static unsigned char __buf[sizeof(type)]; |
| 508 |
static type* __r = new(__buf) type; |
| 509 |
return __r; |
| 510 |
} |
| 511 |
|
| 512 |
inline memory_resource* |
| 513 |
null_memory_resource() noexcept |
| 514 |
{ |
| 515 |
class type final : public memory_resource |
| 516 |
{ |
| 517 |
void* |
| 518 |
do_allocate(size_t, size_t) override |
| 519 |
{ std::__throw_bad_alloc(); } |
| 520 |
|
| 521 |
void |
| 522 |
do_deallocate(void*, size_t, size_t) noexcept override |
| 523 |
{ } |
| 524 |
|
| 525 |
bool |
| 526 |
do_is_equal(const memory_resource& __other) const noexcept override |
| 527 |
{ return this == &__other; } |
| 528 |
}; |
| 529 |
|
| 530 |
alignas(type) static unsigned char __buf[sizeof(type)]; |
| 531 |
static type* __r = new(__buf) type; |
| 532 |
return __r; |
| 533 |
} |
| 534 |
|
| 535 |
// The default memory resource |
| 536 |
|
| 537 |
/// @cond undocumented |
| 538 |
inline std::atomic<memory_resource*>& |
| 539 |
__get_default_resource() |
| 540 |
{ |
| 541 |
using type = atomic<memory_resource*>; |
| 542 |
alignas(type) static unsigned char __buf[sizeof(type)]; |
| 543 |
static type* __r = new(__buf) type(new_delete_resource()); |
| 544 |
return *__r; |
| 545 |
} |
| 546 |
/// @endcond |
| 547 |
|
| 548 |
/// Get the current default resource. |
| 549 |
inline memory_resource* |
| 550 |
get_default_resource() noexcept |
| 551 |
{ return __get_default_resource().load(); } |
| 552 |
|
| 553 |
/// Change the default resource and return the previous one. |
| 554 |
inline memory_resource* |
| 555 |
set_default_resource(memory_resource* __r) noexcept |
| 556 |
{ |
| 557 |
if (__r == nullptr) |
| 558 |
__r = new_delete_resource(); |
| 559 |
return __get_default_resource().exchange(__r); |
| 560 |
} |
| 561 |
|
| 562 |
} // namespace pmr |
| 563 |
} // namespace fundamentals_v2 |
| 564 |
} // namespace experimental |
| 565 |
|
| 566 |
_GLIBCXX_END_NAMESPACE_VERSION |
| 567 |
} // namespace std |
| 568 |
#endif // C++14 |
| 569 |
#endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE |
