1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/org/sonews/util/TimeoutMap.java Wed Jul 01 10:48:22 2009 +0200
1.3 @@ -0,0 +1,145 @@
1.4 +/*
1.5 + * SONEWS News Server
1.6 + * see AUTHORS for the list of contributors
1.7 + *
1.8 + * This program is free software: you can redistribute it and/or modify
1.9 + * it under the terms of the GNU General Public License as published by
1.10 + * the Free Software Foundation, either version 3 of the License, or
1.11 + * (at your option) any later version.
1.12 + *
1.13 + * This program is distributed in the hope that it will be useful,
1.14 + * but WITHOUT ANY WARRANTY; without even the implied warranty of
1.15 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
1.16 + * GNU General Public License for more details.
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License
1.19 + * along with this program. If not, see <http://www.gnu.org/licenses/>.
1.20 + */
1.21 +
1.22 +package org.sonews.util;
1.23 +
1.24 +import java.util.HashMap;
1.25 +import java.util.HashSet;
1.26 +import java.util.Map;
1.27 +import java.util.Set;
1.28 +import java.util.concurrent.ConcurrentHashMap;
1.29 +
1.30 +/**
1.31 + * Implementation of a Map that will loose its stored values after a
1.32 + * configurable amount of time.
1.33 + * This class may be used to cache config values for example.
1.34 + * @author Christian Lins
1.35 + * @since sonews/0.5.0
1.36 + */
1.37 +public class TimeoutMap<K,V> extends ConcurrentHashMap<K, V>
1.38 +{
1.39 +
1.40 + private static final long serialVersionUID = 453453467700345L;
1.41 +
1.42 + private int timeout = 60000; // 60 sec
1.43 + private transient Map<K, Long> timeoutMap = new HashMap<K, Long>();
1.44 +
1.45 + /**
1.46 + * Constructor.
1.47 + * @param timeout Timeout in milliseconds
1.48 + */
1.49 + public TimeoutMap(final int timeout)
1.50 + {
1.51 + this.timeout = timeout;
1.52 + }
1.53 +
1.54 + /**
1.55 + * Uses default timeout (60 sec).
1.56 + */
1.57 + public TimeoutMap()
1.58 + {
1.59 + }
1.60 +
1.61 + /**
1.62 + *
1.63 + * @param key
1.64 + * @return true if key is still valid.
1.65 + */
1.66 + protected boolean checkTimeOut(Object key)
1.67 + {
1.68 + synchronized(this.timeoutMap)
1.69 + {
1.70 + if(this.timeoutMap.containsKey(key))
1.71 + {
1.72 + long keytime = this.timeoutMap.get(key);
1.73 + if((System.currentTimeMillis() - keytime) < this.timeout)
1.74 + {
1.75 + return true;
1.76 + }
1.77 + else
1.78 + {
1.79 + remove(key);
1.80 + return false;
1.81 + }
1.82 + }
1.83 + else
1.84 + {
1.85 + return false;
1.86 + }
1.87 + }
1.88 + }
1.89 +
1.90 + @Override
1.91 + public boolean containsKey(Object key)
1.92 + {
1.93 + return checkTimeOut(key);
1.94 + }
1.95 +
1.96 + @Override
1.97 + public synchronized V get(Object key)
1.98 + {
1.99 + if(checkTimeOut(key))
1.100 + {
1.101 + return super.get(key);
1.102 + }
1.103 + else
1.104 + {
1.105 + return null;
1.106 + }
1.107 + }
1.108 +
1.109 + @Override
1.110 + public V put(K key, V value)
1.111 + {
1.112 + synchronized(this.timeoutMap)
1.113 + {
1.114 + removeStaleKeys();
1.115 + this.timeoutMap.put(key, System.currentTimeMillis());
1.116 + return super.put(key, value);
1.117 + }
1.118 + }
1.119 +
1.120 + /**
1.121 + * @param arg0
1.122 + * @return
1.123 + */
1.124 + @Override
1.125 + public V remove(Object arg0)
1.126 + {
1.127 + synchronized(this.timeoutMap)
1.128 + {
1.129 + this.timeoutMap.remove(arg0);
1.130 + V val = super.remove(arg0);
1.131 + return val;
1.132 + }
1.133 + }
1.134 +
1.135 + protected void removeStaleKeys()
1.136 + {
1.137 + synchronized(this.timeoutMap)
1.138 + {
1.139 + Set<Object> keySet = new HashSet<Object>(this.timeoutMap.keySet());
1.140 + for(Object key : keySet)
1.141 + {
1.142 + // The key/value is removed by the checkTimeOut() method if true
1.143 + checkTimeOut(key);
1.144 + }
1.145 + }
1.146 + }
1.147 +
1.148 +}