boost/container/pmr/resource_adaptor.hpp
//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2015-2015. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/container for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#ifndef BOOST_CONTAINER_PMR_RESOURCE_ADAPTOR_HPP
#define BOOST_CONTAINER_PMR_RESOURCE_ADAPTOR_HPP
#if defined (_MSC_VER)
# pragma once
#endif
#include <boost/container/detail/config_begin.hpp>
#include <boost/container/detail/workaround.hpp>
#include <boost/container/container_fwd.hpp>
#include <boost/container/pmr/memory_resource.hpp>
#include <boost/container/allocator_traits.hpp>
#include <boost/intrusive/detail/ebo_functor_holder.hpp>
#include <boost/move/utility_core.hpp>
#include <boost/move/detail/type_traits.hpp>
#include <boost/container/detail/std_fwd.hpp>
#include <cstring>
namespace boost {
namespace container {
namespace pmr_dtl {
template<class T>
struct max_allocator_alignment
{
static const std::size_t value = 1;
};
template<class T>
struct max_allocator_alignment< ::boost::container::new_allocator<T> >
{
static const std::size_t value = boost::move_detail::alignment_of<boost::move_detail::max_align_t>::value;
};
template<class T>
struct max_allocator_alignment< std::allocator<T> >
{
static const std::size_t value = boost::move_detail::alignment_of<boost::move_detail::max_align_t>::value;
};
} //namespace pmr_dtl
namespace pmr {
//! An instance of resource_adaptor<Allocator> is an adaptor that wraps a memory_resource interface
//! around Allocator. In order that resource_adaptor<X<T>> and resource_adaptor<X<U>> are the same
//! type for any allocator template X and types T and U, resource_adaptor<Allocator> is rendered as
//! an alias to this class template such that Allocator is rebound to a char value type in every
//! specialization of the class template. The requirements on this class template are defined below.
//! In addition to the Allocator requirements, the parameter to resource_adaptor shall meet
//! the following additional requirements:
//!
//! - `typename allocator_traits<Allocator>:: pointer` shall be identical to
//! `typename allocator_traits<Allocator>:: value_type*`.
//!
//! - `typename allocator_traits<Allocator>:: const_pointer` shall be identical to
//! `typename allocator_traits<Allocator>:: value_type const*`.
//!
//! - `typename allocator_traits<Allocator>:: void_pointer` shall be identical to `void*`.
//!
//! - `typename allocator_traits<Allocator>:: const_void_pointer` shall be identical to `void const*`.
template <class Allocator>
class resource_adaptor_imp
: public memory_resource
#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
, private ::boost::intrusive::detail::ebo_functor_holder<Allocator>
#endif
{
#ifdef BOOST_CONTAINER_DOXYGEN_INVOKED
Allocator m_alloc;
#else
BOOST_COPYABLE_AND_MOVABLE(resource_adaptor_imp)
typedef ::boost::intrusive::detail::ebo_functor_holder<Allocator> ebo_alloc_t;
void static_assert_if_not_char_allocator() const
{
//This class can only be used with allocators type char
BOOST_STATIC_ASSERT((boost::container::dtl::is_same<typename Allocator::value_type, char>::value));
}
#endif
public:
typedef Allocator allocator_type;
//! <b>Effects</b>: Default constructs
//! m_alloc.
resource_adaptor_imp()
{ this->static_assert_if_not_char_allocator(); }
//! <b>Effects</b>: Copy constructs
//! m_alloc.
resource_adaptor_imp(const resource_adaptor_imp &other)
: ebo_alloc_t(other.ebo_alloc_t::get())
{}
//! <b>Effects</b>: Move constructs
//! m_alloc.
resource_adaptor_imp(BOOST_RV_REF(resource_adaptor_imp) other)
: ebo_alloc_t(::boost::move(other.get()))
{}
//! <b>Effects</b>: Initializes m_alloc with
//! a2.
explicit resource_adaptor_imp(const Allocator& a2)
: ebo_alloc_t(a2)
{ this->static_assert_if_not_char_allocator(); }
//! <b>Effects</b>: Initializes m_alloc with
//! a2.
explicit resource_adaptor_imp(BOOST_RV_REF(Allocator) a2)
: ebo_alloc_t(::boost::move(a2))
{ this->static_assert_if_not_char_allocator(); }
//! <b>Effects</b>: Copy assigns
//! m_alloc.
resource_adaptor_imp& operator=(BOOST_COPY_ASSIGN_REF(resource_adaptor_imp) other)
{ this->ebo_alloc_t::get() = other.ebo_alloc_t::get(); return *this; }
//! <b>Effects</b>: Move assigns
//! m_alloc.
resource_adaptor_imp& operator=(BOOST_RV_REF(resource_adaptor_imp) other)
{ this->ebo_alloc_t::get() = ::boost::move(other.ebo_alloc_t::get()); return *this; }
//! <b>Effects</b>: Returns m_alloc.
allocator_type &get_allocator()
{ return this->ebo_alloc_t::get(); }
//! <b>Effects</b>: Returns m_alloc.
const allocator_type &get_allocator() const
{ return this->ebo_alloc_t::get(); }
protected:
//! <b>Returns</b>: Allocated memory obtained by calling m_alloc.allocate. The size and alignment
//! of the allocated memory shall meet the requirements for a class derived from memory_resource.
virtual void* do_allocate(std::size_t bytes, std::size_t alignment)
{
if (alignment <= priv_guaranteed_allocator_alignment())
return this->ebo_alloc_t::get().allocate(bytes);
else
return this->priv_aligned_alloc(bytes, alignment);
}
//! <b>Requires</b>: p was previously allocated using A.allocate, where A == m_alloc, and not
//! subsequently deallocated.
//!
//! <b>Effects</b>: Returns memory to the allocator using m_alloc.deallocate().
virtual void do_deallocate(void* p, std::size_t bytes, std::size_t alignment)
{
if (alignment <= priv_guaranteed_allocator_alignment())
this->ebo_alloc_t::get().deallocate((char*)p, bytes);
else
this->priv_aligned_dealloc(p, bytes, alignment);
}
//! Let p be dynamic_cast<const resource_adaptor_imp*>(&other).
//!
//! <b>Returns</b>: false if p is null, otherwise the value of m_alloc == p->m_alloc.
virtual bool do_is_equal(const memory_resource& other) const BOOST_NOEXCEPT
{
const resource_adaptor_imp* p = dynamic_cast<const resource_adaptor_imp*>(&other);
return p && p->ebo_alloc_t::get() == this->ebo_alloc_t::get();
}
private:
void * priv_aligned_alloc(std::size_t bytes, std::size_t alignment)
{
//Allocate space for requested bytes, plus alignment, plus bookeeping data
void *const p = this->ebo_alloc_t::get().allocate(bytes + priv_extra_bytes_for_overalignment(alignment));
if (0 != p) {
//Obtain the aligned address after the bookeeping data
void *const aligned_ptr = (void*)(((std::size_t)p + priv_extra_bytes_for_overalignment(alignment)) & ~(alignment - 1));
//Store bookeeping data. Use memcpy as the underlying memory might be unaligned for
//a pointer (e.g. 2 byte alignment in 32 bit, 4 byte alignment in 64 bit)
std::memcpy(priv_bookeeping_addr_from_aligned_ptr(aligned_ptr), &p, sizeof(p));
return aligned_ptr;
}
return 0;
}
void priv_aligned_dealloc(void *aligned_ptr, std::size_t bytes, std::size_t alignment)
{
//Obtain bookeeping data
void *p;
std::memcpy(&p, priv_bookeeping_addr_from_aligned_ptr(aligned_ptr), sizeof(p));
std::size_t s = bytes + priv_extra_bytes_for_overalignment(alignment);
this->ebo_alloc_t::get().deallocate((char*)p, s);
}
static BOOST_CONTAINER_FORCEINLINE void *priv_bookeeping_addr_from_aligned_ptr(void *aligned_ptr)
{
return reinterpret_cast<void*>(reinterpret_cast<std::size_t>(aligned_ptr) - sizeof(void*));
}
BOOST_CONTAINER_FORCEINLINE static std::size_t priv_extra_bytes_for_overalignment(std::size_t alignment)
{
return alignment - 1 + sizeof(void*);
}
BOOST_CONTAINER_FORCEINLINE static std::size_t priv_guaranteed_allocator_alignment()
{
return pmr_dtl::max_allocator_alignment<Allocator>::value;
}
};
#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES) || defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
//! `resource_adaptor<Allocator>` is rendered as an alias to resource_adaptor_imp class template
//! such that Allocator is rebound to a char value type.
template <class Allocator>
using resource_adaptor = resource_adaptor_imp
<typename allocator_traits<Allocator>::template rebind_alloc<char> >;
#else
template <class Allocator>
class resource_adaptor
: public resource_adaptor_imp
<typename allocator_traits<Allocator>::template portable_rebind_alloc<char>::type>
{
typedef resource_adaptor_imp
<typename allocator_traits<Allocator>::template portable_rebind_alloc<char>::type> base_t;
BOOST_COPYABLE_AND_MOVABLE(resource_adaptor)
public:
resource_adaptor()
: base_t()
{}
resource_adaptor(const resource_adaptor &other)
: base_t(other)
{}
resource_adaptor(BOOST_RV_REF(resource_adaptor) other)
: base_t(BOOST_MOVE_BASE(base_t, other))
{}
explicit resource_adaptor(const Allocator& a2)
: base_t(a2)
{}
explicit resource_adaptor(BOOST_RV_REF(Allocator) a2)
: base_t(::boost::move(a2))
{}
resource_adaptor& operator=(BOOST_COPY_ASSIGN_REF(resource_adaptor) other)
{ return static_cast<resource_adaptor&>(this->base_t::operator=(other)); }
resource_adaptor& operator=(BOOST_RV_REF(resource_adaptor) other)
{ return static_cast<resource_adaptor&>(this->base_t::operator=(BOOST_MOVE_BASE(base_t, other))); }
//get_allocator and protected functions are properly inherited
};
#endif
} //namespace pmr {
} //namespace container {
} //namespace boost {
#include <boost/container/detail/config_end.hpp>
#endif //BOOST_CONTAINER_PMR_RESOURCE_ADAPTOR_HPP