objcache.h

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/******************************************************************************
 *
 * $Id:$
 *
 * Copyright (C) 1997-2008 by Dimitri van Heesch.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation under the terms of the GNU General Public License is hereby 
 * granted. No representations are made about the suitability of this software 
 * for any purpose. It is provided "as is" without express or implied warranty.
 * See the GNU General Public License for more details.
 *
 * Documents produced by Doxygen are derivative works derived from the
 * input used in their production; they are not affected by this license.
 *
 */

#ifndef OBJCACHE_H
#define OBJCACHE_H

//#define CACHE_TEST
//#define CACHE_DEBUG
#define CACHE_STATS

class ObjCache
{
  private:
    struct CacheNode
    {
      CacheNode() : next(-1), prev(-1), obj(0) {}
      int next;
      int prev;
      void *obj;
    };
    struct HashNode
    {
      HashNode() : head(-1), nextHash(-1), index(-1), obj(0) {}
      int head;
      int nextHash; 
      int index;
      void *obj;
    };

  public:
    ObjCache(unsigned int logSize);

   ~ObjCache();

    int add(void *obj,void **victim);

    void use(int handle)
    {
      hits++;
      if (handle==m_lastHandle) return;
      m_lastHandle = handle;
      moveToFront(handle);
    }

    void del(int handle);

    void printLRU();
    void printStats();

  private:
    void moveToFront(int index);
    unsigned int hash(void *addr);
    HashNode *hashFind(void *obj);
    HashNode *hashInsert(void *obj);
    void hashRemove(void *obj);

    CacheNode *m_cache;
    HashNode  *m_hash;
    int        m_head;
    int        m_tail;
    int        m_size;
    int        m_freeHashNodes;
    int        m_freeCacheNodes;
    int        m_lastHandle;

#ifdef CACHE_STATS
    static int misses;
    static int hits;
#endif
};

#endif // OBJCACHE_H

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