001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.services.impl;
016    
017    import java.util.HashMap;
018    import java.util.Iterator;
019    import java.util.LinkedList;
020    import java.util.List;
021    import java.util.Map;
022    
023    import org.apache.tapestry.event.ReportStatusEvent;
024    import org.apache.tapestry.event.ReportStatusListener;
025    import org.apache.tapestry.event.ResetEventListener;
026    import org.apache.tapestry.services.ObjectPool;
027    
028    /**
029     * Implementation of the {@link org.apache.tapestry.services.ObjectPool} interface.
030     * <p>
031     * This ia a minimal implementation, one that has no concept of automatically removing unused pooled
032     * objects. Eventually, it will also register for notifications about general cache cleaning.
033     * 
034     * @author Howard Lewis Ship
035     * @since 4.0
036     */
037    public class ObjectPoolImpl implements ObjectPool, ResetEventListener, ReportStatusListener
038    {
039        private String _serviceId;
040    
041        private int _count = 0;
042    
043        /**
044         * Pool of Lists (of pooled objects), keyed on arbitrary key.
045         */
046        private Map _pool = new HashMap();
047    
048        public synchronized Object get(Object key)
049        {
050            List pooled = (List) _pool.get(key);
051    
052            if (pooled == null || pooled.isEmpty())
053                return null;
054    
055            _count--;
056    
057            return pooled.remove(0);
058        }
059    
060        public synchronized void store(Object key, Object value)
061        {
062            List pooled = (List) _pool.get(key);
063    
064            if (pooled == null)
065            {
066                pooled = new LinkedList();
067                _pool.put(key, pooled);
068            }
069    
070            pooled.add(value);
071    
072            _count++;
073        }
074    
075        public synchronized void resetEventDidOccur()
076        {
077            _pool.clear();
078    
079            _count = 0;
080        }
081    
082        public synchronized void reportStatus(ReportStatusEvent event)
083        {
084            event.title(_serviceId);
085    
086            event.property("total count", _count);
087    
088            event.section("Count by Key");
089    
090            Iterator i = _pool.entrySet().iterator();
091    
092            while (i.hasNext())
093            {
094                Map.Entry entry = (Map.Entry) i.next();
095    
096                String key = entry.getKey().toString();
097    
098                List pooled = (List) entry.getValue();
099    
100                event.property(key, pooled.size());
101            }
102        }
103    
104        public void setServiceId(String serviceId)
105        {
106            _serviceId = serviceId;
107        }
108    
109    }