fixed_mem_pool.h

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// -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
// vim:tabstop=4:shiftwidth=4:expandtab:

/*
 * Copyright (C) 2004-2005 Wu Yongwei <adah at users dot sourceforge dot net>
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any
 * damages arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute
 * it freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must
 *    not claim that you wrote the original software. If you use this
 *    software in a product, an acknowledgment in the product
 *    documentation would be appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must
 *    not be misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source
 *    distribution.
 *
 * This file is part of Stones of Nvwa:
 *      http://sourceforge.net/projects/nvwa
 *
 */

#ifndef _FIXED_MEM_POOL_H
#define _FIXED_MEM_POOL_H

#include <new>
#include <assert.h>
#include <stdlib.h>
#include "class_level_lock.h"
#include "mem_pool_base.h"

#ifndef MEM_POOL_ALIGNMENT
#define MEM_POOL_ALIGNMENT 4
#endif

template <class _Tp>
class fixed_mem_pool
{
public:
    typedef typename class_level_lock<fixed_mem_pool<_Tp> >::lock lock;
    static void*  allocate();
    static void   deallocate(void*);
    static bool   initialize(size_t __size);
    static int    deinitialize();
    static int    get_alloc_count();
    static bool   is_initialized();
protected:
    static bool   bad_alloc_handler();
private:
    static size_t _S_align(size_t __size);
    static void*  _S_mem_pool_ptr;
    static void*  _S_first_avail_ptr;
    static int    _S_alloc_cnt;
};

template <class _Tp>
void* fixed_mem_pool<_Tp>::_S_mem_pool_ptr = NULL;

template <class _Tp>
void* fixed_mem_pool<_Tp>::_S_first_avail_ptr = NULL;

template <class _Tp>
int   fixed_mem_pool<_Tp>::_S_alloc_cnt = 0;

template <class _Tp>
inline void* fixed_mem_pool<_Tp>::allocate()
{
    lock __guard;
    for (;;)
    {
        if (void* __result = _S_first_avail_ptr)
        {
            _S_first_avail_ptr = *(void**)_S_first_avail_ptr;
            ++_S_alloc_cnt;
            return __result;
        }
        else
            if (!bad_alloc_handler())
                return NULL;
    }
}

template <class _Tp>
inline void fixed_mem_pool<_Tp>::deallocate(void* __block_ptr)
{
    if (__block_ptr == NULL)
        return;
    lock __guard;
    assert(_S_alloc_cnt != 0);
    --_S_alloc_cnt;
    *(void**)__block_ptr = _S_first_avail_ptr;
    _S_first_avail_ptr = __block_ptr;
}

template <class _Tp>
bool fixed_mem_pool<_Tp>::initialize(size_t __size)
{
    size_t __block_size = _S_align(sizeof(_Tp));
    assert(!is_initialized());
    assert(__size > 0 && __block_size >= sizeof(void*));
    _S_mem_pool_ptr = mem_pool_base::alloc_sys(__size * __block_size);
    _S_first_avail_ptr = _S_mem_pool_ptr;
    if (_S_mem_pool_ptr == NULL)
        return false;
    char* __block = (char*)_S_mem_pool_ptr;
    while (--__size != 0)
    {
        char* __next = __block + __block_size;
        *(void**)__block = __next;
        __block = __next;
    }
    *(void**)__block = NULL;
    return true;
}

template <class _Tp>
int fixed_mem_pool<_Tp>::deinitialize()
{
    if (_S_alloc_cnt != 0)
        return _S_alloc_cnt;
    assert(is_initialized());
    mem_pool_base::dealloc_sys(_S_mem_pool_ptr);
    _S_mem_pool_ptr = NULL;
    _S_first_avail_ptr = NULL;
    return 0;
}

template <class _Tp>
inline int fixed_mem_pool<_Tp>::get_alloc_count()
{
    return _S_alloc_cnt;
}

template <class _Tp>
inline bool fixed_mem_pool<_Tp>::is_initialized()
{
    return _S_mem_pool_ptr != NULL;;
}

template <class _Tp>
bool fixed_mem_pool<_Tp>::bad_alloc_handler()
{
    return false;
}

template <class _Tp>
inline size_t fixed_mem_pool<_Tp>::_S_align(size_t __size)
{
    return (__size + MEM_POOL_ALIGNMENT - 1)
           / MEM_POOL_ALIGNMENT * MEM_POOL_ALIGNMENT;
}

#define DECLARE_FIXED_MEM_POOL(_Cls) \
public: \
    static void* operator new(size_t __size) \
    { \
        assert(__size == sizeof(_Cls)); \
        if (void* __ptr = fixed_mem_pool<_Cls>::allocate()) \
            return __ptr; \
        else \
            throw std::bad_alloc(); \
    } \
    static void  operator delete(void* __ptr) \
    { \
        if (__ptr != NULL) \
            fixed_mem_pool<_Cls>::deallocate(__ptr); \
    }

#define DECLARE_FIXED_MEM_POOL__NOTHROW(_Cls) \
public: \
    static void* operator new(size_t __size) throw() \
    { \
        assert(__size == sizeof(_Cls)); \
        return fixed_mem_pool<_Cls>::allocate(); \
    } \
    static void  operator delete(void* __ptr) \
    { \
        if (__ptr != NULL) \
            fixed_mem_pool<_Cls>::deallocate(__ptr); \
    }

#define DECLARE_FIXED_MEM_POOL__THROW_NOCHECK(_Cls) \
public: \
    static void* operator new(size_t __size) \
    { \
        assert(__size == sizeof(_Cls)); \
        return fixed_mem_pool<_Cls>::allocate(); \
    } \
    static void  operator delete(void* __ptr) \
    { \
        if (__ptr != NULL) \
            fixed_mem_pool<_Cls>::deallocate(__ptr); \
    }

#endif // _FIXED_MEM_POOL_H