chris@1: /*
chris@1:  *   SONEWS News Server
chris@1:  *   see AUTHORS for the list of contributors
chris@1:  *
chris@1:  *   This program is free software: you can redistribute it and/or modify
chris@1:  *   it under the terms of the GNU General Public License as published by
chris@1:  *   the Free Software Foundation, either version 3 of the License, or
chris@1:  *   (at your option) any later version.
chris@1:  *
chris@1:  *   This program is distributed in the hope that it will be useful,
chris@1:  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
chris@1:  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
chris@1:  *   GNU General Public License for more details.
chris@1:  *
chris@1:  *   You should have received a copy of the GNU General Public License
chris@1:  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
chris@1:  */
chris@1: 
chris@1: package org.sonews.util;
chris@1: 
chris@1: import java.util.HashMap;
chris@1: import java.util.HashSet;
chris@1: import java.util.Map;
chris@1: import java.util.Set;
chris@1: import java.util.concurrent.ConcurrentHashMap;
chris@1: 
chris@1: /**
chris@1:  * Implementation of a Map that will loose its stored values after a 
chris@1:  * configurable amount of time.
chris@1:  * This class may be used to cache config values for example.
chris@1:  * @author Christian Lins
chris@1:  * @since sonews/0.5.0
chris@1:  */
chris@1: public class TimeoutMap<K,V> extends ConcurrentHashMap<K, V>
chris@1: {
chris@1:   
chris@1:   private static final long serialVersionUID = 453453467700345L;
chris@1: 
chris@1:   private int                    timeout     = 60000; // 60 sec
chris@1:   private transient Map<K, Long> timeoutMap  = new HashMap<K, Long>();
chris@1:   
chris@1:   /**
chris@1:    * Constructor.
chris@1:    * @param timeout Timeout in milliseconds
chris@1:    */
chris@1:   public TimeoutMap(final int timeout)
chris@1:   {
chris@1:     this.timeout = timeout;
chris@1:   }
chris@1:   
chris@1:   /**
chris@1:    * Uses default timeout (60 sec).
chris@1:    */
chris@1:   public TimeoutMap()
chris@1:   {
chris@1:   }
chris@1:   
chris@1:   /**
chris@1:    * 
chris@1:    * @param key
chris@1:    * @return true if key is still valid.
chris@1:    */
chris@1:   protected boolean checkTimeOut(Object key)
chris@1:   {
chris@1:     synchronized(this.timeoutMap)
chris@1:     {
chris@1:       if(this.timeoutMap.containsKey(key))
chris@1:       {
chris@1:         long keytime = this.timeoutMap.get(key);
chris@1:         if((System.currentTimeMillis() - keytime) < this.timeout)
chris@1:         {
chris@1:           return true;
chris@1:         }
chris@1:         else
chris@1:         {
chris@1:           remove(key);
chris@1:           return false;
chris@1:         }
chris@1:       }
chris@1:       else
chris@1:       {
chris@1:         return false;
chris@1:       }
chris@1:     }
chris@1:   }
chris@1:   
chris@1:   @Override
chris@1:   public boolean containsKey(Object key)
chris@1:   {
chris@1:     return checkTimeOut(key);
chris@1:   }
chris@1: 
chris@1:   @Override
chris@1:   public synchronized V get(Object key)
chris@1:   {
chris@1:     if(checkTimeOut(key))
chris@1:     {
chris@1:       return super.get(key);
chris@1:     }
chris@1:     else
chris@1:     {
chris@1:       return null;
chris@1:     }
chris@1:   }
chris@1: 
chris@1:   @Override
chris@1:   public V put(K key, V value)
chris@1:   {
chris@1:     synchronized(this.timeoutMap)
chris@1:     {
chris@1:       removeStaleKeys();
chris@1:       this.timeoutMap.put(key, System.currentTimeMillis());
chris@1:       return super.put(key, value);
chris@1:     }
chris@1:   }
chris@1: 
chris@1:   /**
chris@1:    * @param arg0
chris@1:    * @return
chris@1:    */
chris@1:   @Override
chris@1:   public V remove(Object arg0)
chris@1:   {
chris@1:     synchronized(this.timeoutMap)
chris@1:     {
chris@1:       this.timeoutMap.remove(arg0);
chris@1:       V val = super.remove(arg0);
chris@1:       return val;
chris@1:     }
chris@1:   }
chris@1: 
chris@1:   protected void removeStaleKeys()
chris@1:   {
chris@1:     synchronized(this.timeoutMap)
chris@1:     {
chris@1:       Set<Object> keySet = new HashSet<Object>(this.timeoutMap.keySet());
chris@1:       for(Object key : keySet)
chris@1:       {
chris@1:         // The key/value is removed by the checkTimeOut() method if true
chris@1:         checkTimeOut(key);
chris@1:       }
chris@1:     }
chris@1:   }
chris@1:   
chris@1: }