/***************************************************************************
 * 
 * Copyright (c) 2010 Baidu.com, Inc. All Rights Reserved
 * bsl_cachedpoolappend.cpp 2010/01/12 15:31:55 sun_xiao Exp 
 * 
 **************************************************************************/
 
 
 
/**
 * @file bsl_cachedpoolappend.cpp
 * @author sun_xiao(com@baidu.com)
 * @date 2010/01/12 15:31:55
 * @brief 
 *  
 **/

#include "bsl_cachedpoolappend.h"

namespace bsl
{
    void * cached_mempool_append :: malloc(size_t size)
    {
	    if (size <= 0 || NULL == _head) {
	        return 0;
	    }

        if (_buff_freesize >= size) {
            void *p = _free_space;
            _buff_freesize -= size;
            _free_space += size;
            return p;
        } 
        if (size <= _seg_size - sizeof(void *)) {
			while (_seg_usingnum < _seg_num) {
			    if(size > _buff_freesize) {
                    ++ _seg_usingnum;
                    _pre_seg = _curr_seg;
		            _curr_seg = *(void **)_curr_seg;
                    _buff_freesize = _seg_size - sizeof(void *);
                    _free_space = (char *)_curr_seg + sizeof(void *);
				} else {
				    void * p = _free_space;
				    _buff_freesize -= size;
                    _free_space += size;
				    return p;
				}
			}
			void *tmp = ::malloc(_seg_size);
			if(tmp) {
			    *(void **)tmp = NULL;
                *(void **)_pre_seg = tmp;
                _curr_seg = tmp;
                ++ _seg_num;
                _seg_usingnum = _seg_num - 1;

				_free_space = (char *)tmp + sizeof(void *) + size;
				_buff_freesize = _seg_size - sizeof(void *) - size;
				void *p = (char *)tmp + sizeof(void *);
				return p;
            } else {
                return 0;
            }
		} else {
			void *tmp = ::malloc(size + sizeof(void *));
			if(tmp)
			{
				*(void **)tmp = _bigbuf_head;
				_bigbuf_head = tmp;
				return ((char *)tmp + sizeof(void *));
			}
			else {
				return 0;
			}
		}
    }

}



















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