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
015package org.apache.tapestry.services.impl;
016
017import java.util.HashMap;
018import java.util.Iterator;
019import java.util.LinkedList;
020import java.util.List;
021import java.util.Map;
022
023import org.apache.tapestry.event.ReportStatusEvent;
024import org.apache.tapestry.event.ReportStatusListener;
025import org.apache.tapestry.event.ResetEventListener;
026import 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 */
037public 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}