memory pooling - code

MemPooling #

메모리 풀링 클래스

Efficient C++(Dov Bulka , David Mayhew)에서 많은 도움은 얻음
나름대로 좋은 성능을 냄

/**
 * MemPool.h
 *
 * Memory Pooling Class
 *
 * Copyright (c) 2004 by cdecl (byung-kyu kim)
 *
 */

#ifndef __MEM_POOL_H__BY__CDECL
#define __MEM_POOL_H__BY__CDECL


namespace GLASS {

// MemPool Class 
class MemPool
{
public:
    typedef unsigned int size_type;
    enum { DEFAULT_CHUNK_SIZE = 32 };

    struct MemNode { MemNode *next_; };

public:
    MemPool(size_type type_size, size_type chunk_size = DEFAULT_CHUNK_SIZE) :
        pHead_(0), pFree_(0), nUsed_(0),
        TYPESIZE(type_size > sizeof(MemNode*) ? type_size : sizeof(MemNode*)),
        CHUNK_SIZE(chunk_size)
    {
        ExpanseChunk();
    };
    ~MemPool() { Release(); }

public:
    void* malloc()
    {
        if (IsFull()) {
            if (pFree_) return (NodeNext(pFree_));

            ExpanseChunk();
        }

        int nOffSet = sizeof(MemNode*) + (TYPESIZE * nUsed_++);
        return (reinterpret_cast<char*>(pHead_) + nOffSet);
    }

    void free(void *p)
    {
        MemNode *pmn = reinterpret_cast<MemNode*>(p);
        pmn->next_ = pFree_;
        pFree_ = pmn;
    }

    void ExpanseChunk()
    {
        size_type nAllocSize = TYPESIZE * CHUNK_SIZE + sizeof(MemNode*);

        MemNode *pmn =
            reinterpret_cast<MemNode *>(::operator new(nAllocSize));

        nUsed_ = 0;;

        pmn->next_ = pHead_;
        pHead_ = pmn;
    }

    bool IsFull() const
    {
        return nUsed_ >= CHUNK_SIZE;
    }

    void Release()
    {
        while (pHead_ != 0) {
            ::operator delete(NodeNext(pHead_));
        }
    }

private:
    inline MemNode* NodeNext(MemNode *&pmn)
    {
        MemNode *p = pmn;
        pmn = pmn->next_;
        return p;
    }

private:
    // No Copy
    MemPool(const MemPool&);
    MemPool& operator=(const MemPool&);

private:
    MemNode *pHead_;
    MemNode *pFree_;

    size_type nUsed_;

private:
    const size_type TYPESIZE;
    const size_type CHUNK_SIZE;

};


} // namespace GLASS

#endif