001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.monitoring.web.session;
018    
019    import org.apache.commons.monitoring.Role;
020    import org.apache.commons.monitoring.counters.Counter;
021    import org.apache.commons.monitoring.counters.Unit;
022    import org.apache.commons.monitoring.repositories.Repository;
023    import org.apache.commons.monitoring.stopwatches.StopWatch;
024    
025    import javax.servlet.http.HttpSessionEvent;
026    import javax.servlet.http.HttpSessionListener;
027    import java.util.Map;
028    import java.util.concurrent.ConcurrentHashMap;
029    
030    public class MonitoringSessionListener implements HttpSessionListener {
031        private final Map<String, StopWatch> watches = new ConcurrentHashMap<String, StopWatch>();
032    
033        private final Counter counter;
034    
035        public MonitoringSessionListener() {
036            counter = Repository.INSTANCE.getCounter(new Counter.Key(new Role("session", Unit.UNARY), "session"));
037        }
038    
039        @Override
040        public void sessionCreated(final HttpSessionEvent httpSessionEvent) {
041            final StopWatch watch = Repository.INSTANCE.start(counter);
042            watches.put(httpSessionEvent.getSession().getId(), watch);
043        }
044    
045        @Override
046        public void sessionDestroyed(final HttpSessionEvent httpSessionEvent) {
047            final StopWatch watch = watches.remove(httpSessionEvent.getSession().getId());
048            if (watch != null) {
049                watch.stop();
050            }
051        }
052    }