LruCacheController.cs :  » Persistence-Frameworks » iBATIS.NET » IBatisNet » DataMapper » Configuration » Cache » Lru » C# / CSharp Open Source

#region Apache Notice
/*****************************************************************************
 * $Header: $
 * $Revision: 638571 $
 * $Date: 2008-03-18 22:11:57 +0100 (mar., 18 mars 2008) $
 * 
 * iBATIS.NET Data Mapper
 * Copyright (C) 2004 - Gilles Bayon
 *  
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 ********************************************************************************/
#endregion

#region Imports

using System;
using System.Collections;

#endregion

namespace IBatisNet.DataMapper.Configuration.Cache.Lru{
  /// <summary>
  /// Summary description for LruCacheController.
  /// </summary>
  public class LruCacheController : ICacheController  
  {
    #region Fields 
    private int _cacheSize = 0;
    private Hashtable _cache = null;
    private IList _keyList = null;
    #endregion

    #region Constructor (s) / Destructor
    /// <summary>
    /// 
    /// </summary>
    public LruCacheController() 
    {
      _cacheSize = 100;
      _cache = Hashtable.Synchronized( new Hashtable() );
      _keyList = ArrayList.Synchronized( new ArrayList() );
    }
    #endregion

    #region ICacheController Members

    /// <summary>
    /// Remove an object from a cache model
    /// </summary>
    /// <param name="key">the key to the object</param>
    /// <returns>the removed object(?)</returns>
    public object Remove(object key)
    {
      object o = this[key];

      _keyList.Remove(key);
      _cache.Remove(key);
      return o;
    }

    /// <summary>
    /// Clears all elements from the cache.
    /// </summary>
    public void Flush()
    {
      _cache.Clear();
      _keyList.Clear();  
    }


    /// <summary>
    /// Adds an item with the specified key and value into cached data.
    /// Gets a cached object with the specified key.
    /// </summary>
    /// <value>The cached object or <c>null</c></value>
    public object this[object key] 
    {
      get
      {
        _keyList.Remove(key);
        _keyList.Add(key);
        return _cache[key];
      }
      set
      {
        _cache[key] = value;
        _keyList.Add(key);
        if (_keyList.Count > _cacheSize) 
        {
          object oldestKey = _keyList[0];
          _keyList.Remove(0);
          _cache.Remove(oldestKey);
        }    
      }
    }


    /// <summary>
    /// Configures the cache
    /// </summary>
    public void Configure(IDictionary properties)
    {
      string size = (string)properties["CacheSize"];;
      if (size != null) 
      {
        _cacheSize = Convert.ToInt32(size);    
      }    
    }

    #endregion
  }
}