src/org/sonews/util/TimeoutMap.java
author František Kučera <franta-hg@frantovo.cz>
Sat, 05 Nov 2011 00:06:09 +0100
changeset 115 e5bfc969d41f
parent 37 74139325d305
permissions -rwxr-xr-x
SMTP: correct unescaping of posted messages containing lines with single dot.
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/*
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 *   SONEWS News Server
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 *   see AUTHORS for the list of contributors
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 *
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 *   This program is free software: you can redistribute it and/or modify
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 *   it under the terms of the GNU General Public License as published by
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 *   the Free Software Foundation, either version 3 of the License, or
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 *   (at your option) any later version.
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 *
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 *   This program is distributed in the hope that it will be useful,
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 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
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 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 *   GNU General Public License for more details.
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 *
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 *   You should have received a copy of the GNU General Public License
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 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
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 */
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package org.sonews.util;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.ConcurrentHashMap;
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/**
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 * Implementation of a Map that will loose its stored values after a 
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 * configurable amount of time.
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 * This class may be used to cache config values for example.
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 * @author Christian Lins
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 * @since sonews/0.5.0
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 */
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public class TimeoutMap<K, V> extends ConcurrentHashMap<K, V>
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{
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	private static final long serialVersionUID = 453453467700345L;
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	private int timeout = 60000; // 60 sec
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	private transient Map<K, Long> timeoutMap = new HashMap<K, Long>();
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	/**
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	 * Constructor.
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	 * @param timeout Timeout in milliseconds
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	 */
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	public TimeoutMap(final int timeout)
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	{
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		this.timeout = timeout;
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	}
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	/**
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	 * Uses default timeout (60 sec).
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	 */
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	public TimeoutMap()
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	{
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	}
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	/**
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	 *
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	 * @param key
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	 * @return true if key is still valid.
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	 */
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	protected boolean checkTimeOut(Object key)
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	{
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		synchronized (this.timeoutMap) {
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			if (this.timeoutMap.containsKey(key)) {
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				long keytime = this.timeoutMap.get(key);
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				if ((System.currentTimeMillis() - keytime) < this.timeout) {
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					return true;
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				} else {
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					remove(key);
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					return false;
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				}
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			} else {
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				return false;
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			}
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		}
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	}
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	@Override
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	public boolean containsKey(Object key)
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	{
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		return checkTimeOut(key);
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	}
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	@Override
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	public synchronized V get(Object key)
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	{
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		if (checkTimeOut(key)) {
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			return super.get(key);
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		} else {
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			return null;
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		}
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	}
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	@Override
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	public V put(K key, V value)
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	{
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		synchronized (this.timeoutMap) {
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			removeStaleKeys();
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			this.timeoutMap.put(key, System.currentTimeMillis());
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			return super.put(key, value);
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		}
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	}
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	/**
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	 * @param arg0
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	 * @return
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	 */
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	@Override
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	public V remove(Object arg0)
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	{
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		synchronized (this.timeoutMap) {
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			this.timeoutMap.remove(arg0);
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			V val = super.remove(arg0);
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			return val;
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		}
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	}
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	protected void removeStaleKeys()
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	{
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		synchronized (this.timeoutMap) {
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			Set<Object> keySet = new HashSet<Object>(this.timeoutMap.keySet());
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			for (Object key : keySet) {
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				// The key/value is removed by the checkTimeOut() method if true
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				checkTimeOut(key);
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			}
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		}
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	}
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}