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Session of low-level optimization of memory usage in C++ programs with total exposure

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22 Jun 2009CPOL7 min read 39.7K   246   44  
In this article, we will try to make our algorithms work faster using the methods of low-level optimization of memory allocation in C++.
#ifndef resultS_H
#define resultS_H


// USAGE SAMPLE:
//typedef std::map<void*,
//                 void*,
//                 std::less<void*>,
//                 utils::factory<
//                                 utils::paged_allocator,    // allocator type
//                                 utils::without_params      // this type cannot use params
//                               >
//                               ::result
//                               <
//                                  std::pair<
//                                              const void*,
//                                              void*
//                                           >
//                               >
//> VoidPtrSet;

namespace utils
{

struct without_params
{
};

template<class ObjectType, class ParamType>
struct standard_allocator
{
    ObjectType * NewChars(size_t count)
    {
       return (ObjectType * )operator new(count);
    }

    ObjectType * New(size_t count)
    {
       return (ObjectType * )operator new(count * sizeof (ObjectType));
    }

    void Delete(void * ptr, size_t)
    {
       operator delete (ptr);
    }
};

template<template<class,class> class AllocatorStrategy, class AllocatorParams>
struct factory
{
    template<class ObjectType>
    class result
    {
        AllocatorStrategy<ObjectType, AllocatorParams> m_core;

    public:
        typedef ObjectType  value_type;

        typedef value_type  * pointer;
        typedef value_type  & reference;
        typedef const value_type * const_pointer;
        typedef const value_type & const_reference;

        typedef size_t    size_type;
        typedef ptrdiff_t difference_type;

        template<class OtherType>
        struct rebind
        {
            typedef result<OtherType> other;
        };

        pointer address(reference value) 
        {
            return (&value);
        }

        const_pointer address(const_reference value) const
        {
            return (&value);
        }

        // the same type
        result()
        {
        }
        
        result(const result<ObjectType>& same)
            : m_core(same.m_core)
        {
        }
        
        result<ObjectType>& operator=(const result<ObjectType>& same)
        {
            m_core = same.m_core;
            return (*this);
        }

        // other type
        template<class OtherType>
        result(const result<OtherType>& other)
            : m_core(*other.GetCore())
        {
        }

        template<class OtherType>
        result<ObjectType>& operator=(const result<OtherType> & other)
        {
            m_core = *other.GetCore();
            return (*this);
        }


        //----------------------------------------------------------
        // for fucking prematurely born childs from stl port team:
        void * _Charalloc(size_type size)
        {
            return m_core.NewChars( size );
        }

        // instead of standard [void deallocate(C * ptr, size_type size)] form
        void deallocate(void * ptr, size_type size)
        {
            m_core.Delete( ptr, size );
        }
        //----------------------------------------------------------

        pointer allocate(size_type count)
        {
            return m_core.New( count );
        }

        pointer allocate(size_type count, const void *)
        {
            return m_core.New( count );
        }

        void construct(pointer ptr, const ObjectType& val)
        {
            new ((void *)ptr) ObjectType(val);
        }

        void destroy(pointer ptr)
        {
            &ptr;
            ptr->~ObjectType();
        }

        size_t max_size() const
        {
            size_t count = (size_t)(-1) / sizeof (ObjectType);
            return (0 < count ? count : 1);
        }

        template<class OtherType>
        inline bool operator==(const result<OtherType>&)
        {
            return true;
        }

        template<class OtherType>
        inline bool operator!=(const result<OtherType>&)
        {
            return false;
        }

        // non standard extension
        typedef AllocatorStrategy<ObjectType, AllocatorParams> core_type;

        AllocatorStrategy<ObjectType, AllocatorParams> * GetCore()
        {
            return &m_core;
        }
        const AllocatorStrategy<ObjectType, AllocatorParams> * GetCore() const
        {
            return &m_core;
        }

    };
};


#define DEFINE_TEMPLATE_CONSTRUCTORS(X)\
    X()\
    {\
    }\
    template<class __otherType>\
    X(const __otherType & )\
    {\
    }\
    template<class __otherType>\
    X & operator = (const __otherType & )\
    {\
        return *this; \
    }
} // utils
#endif

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Chief Technology Officer Apriorit Inc.
United States United States
ApriorIT is a software research and development company specializing in cybersecurity and data management technology engineering. We work for a broad range of clients from Fortune 500 technology leaders to small innovative startups building unique solutions.

As Apriorit offers integrated research&development services for the software projects in such areas as endpoint security, network security, data security, embedded Systems, and virtualization, we have strong kernel and driver development skills, huge system programming expertise, and are reals fans of research projects.

Our specialty is reverse engineering, we apply it for security testing and security-related projects.

A separate department of Apriorit works on large-scale business SaaS solutions, handling tasks from business analysis, data architecture design, and web development to performance optimization and DevOps.

Official site: https://www.apriorit.com
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