sonews-drupal: src/org/sonews/util/TimeoutMap.java@ca54040b4409

     1 /*

     2  *   SONEWS News Server

     3  *   see AUTHORS for the list of contributors

     4  *

     5  *   This program is free software: you can redistribute it and/or modify

     6  *   it under the terms of the GNU General Public License as published by

     7  *   the Free Software Foundation, either version 3 of the License, or

     8  *   (at your option) any later version.

     9  *

    10  *   This program is distributed in the hope that it will be useful,

    11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of

    12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    13  *   GNU General Public License for more details.

    14  *

    15  *   You should have received a copy of the GNU General Public License

    16  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.

    17  */

    19 package org.sonews.util;

    21 import java.util.HashMap;

    22 import java.util.HashSet;

    23 import java.util.Map;

    24 import java.util.Set;

    25 import java.util.concurrent.ConcurrentHashMap;

    27 /**

    28  * Implementation of a Map that will loose its stored values after a

    29  * configurable amount of time.

    30  * This class may be used to cache config values for example.

    31  * @author Christian Lins

    32  * @since sonews/0.5.0

    33  */

    34 public class TimeoutMap<K, V> extends ConcurrentHashMap<K, V>

    35 {

    37 	private static final long serialVersionUID = 453453467700345L;

    38 	private int timeout = 60000; // 60 sec

    39 	private transient Map<K, Long> timeoutMap = new HashMap<K, Long>();

    41 	/**

    42 	 * Constructor.

    43 	 * @param timeout Timeout in milliseconds

    44 	 */

    45 	public TimeoutMap(final int timeout)

    46 	{

    47 		this.timeout = timeout;

    48 	}

    50 	/**

    51 	 * Uses default timeout (60 sec).

    52 	 */

    53 	public TimeoutMap()

    54 	{

    55 	}

    57 	/**

    58 	 *

    59 	 * @param key

    60 	 * @return true if key is still valid.

    61 	 */

    62 	protected boolean checkTimeOut(Object key)

    63 	{

    64 		synchronized (this.timeoutMap) {

    65 			if (this.timeoutMap.containsKey(key)) {

    66 				long keytime = this.timeoutMap.get(key);

    67 				if ((System.currentTimeMillis() - keytime) < this.timeout) {

    68 					return true;

    69 				} else {

    70 					remove(key);

    71 					return false;

    72 				}

    73 			} else {

    74 				return false;

    75 			}

    76 		}

    77 	}

    79 	@Override

    80 	public boolean containsKey(Object key)

    81 	{

    82 		return checkTimeOut(key);

    83 	}

    85 	@Override

    86 	public synchronized V get(Object key)

    87 	{

    88 		if (checkTimeOut(key)) {

    89 			return super.get(key);

    90 		} else {

    91 			return null;

    92 		}

    93 	}

    95 	@Override

    96 	public V put(K key, V value)

    97 	{

    98 		synchronized (this.timeoutMap) {

    99 			removeStaleKeys();

   100 			this.timeoutMap.put(key, System.currentTimeMillis());

   101 			return super.put(key, value);

   102 		}

   103 	}

   105 	/**

   106 	 * @param arg0

   107 	 * @return

   108 	 */

   109 	@Override

   110 	public V remove(Object arg0)

   111 	{

   112 		synchronized (this.timeoutMap) {

   113 			this.timeoutMap.remove(arg0);

   114 			V val = super.remove(arg0);

   115 			return val;

   116 		}

   117 	}

   119 	protected void removeStaleKeys()

   120 	{

   121 		synchronized (this.timeoutMap) {

   122 			Set<Object> keySet = new HashSet<Object>(this.timeoutMap.keySet());

   123 			for (Object key : keySet) {

   124 				// The key/value is removed by the checkTimeOut() method if true

   125 				checkTimeOut(key);

   126 			}

   127 		}

   128 	}

   129 }

author	František Kučera <franta-hg@frantovo.cz>
	Sun, 30 Oct 2011 22:13:32 +0100
changeset 112	ca54040b4409
parent 37	74139325d305
permissions	-rwxr-xr-x