001package org.apache.turbine.om;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 *
012 *   http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import java.util.concurrent.ConcurrentHashMap;
023import java.util.concurrent.ConcurrentMap;
024
025import org.apache.fulcrum.pool.Recyclable;
026import org.apache.turbine.Turbine;
027import org.apache.turbine.services.pull.ApplicationTool;
028
029/**
030 * A Pull tool to make om objects available to a template
031 *
032 * @author <a href="mailto:jmcnally@collab.net">John D. McNally</a>
033 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
034 * @version $Id: OMTool.java 1706425 2015-10-02 14:47:51Z tv $
035 */
036public class OMTool implements ApplicationTool, Recyclable
037{
038    protected ConcurrentHashMap<String, Object> omMap;
039
040    // note the following could be a static attribute to reduce memory
041    // footprint. Might require a service to front load the
042    // PullHelpers to avoid MT issues. A multiple write is not so bad
043    // though
044
045    /** The cache of PullHelpers. **/
046    private ConcurrentMap<String, OMTool.PullHelper> pullMap =
047            new ConcurrentHashMap<String, OMTool.PullHelper>();
048
049    /**
050     *  The Factory responsible for retrieving the
051     *  objects from storage
052     */
053    protected RetrieverFactory omFactory;
054
055    /**
056     * Default constructor
057     * @throws Exception if creating the factory fails
058     */
059    public OMTool() throws Exception
060    {
061        omMap = new ConcurrentHashMap<String, Object>();
062        String className = Turbine.getConfiguration().getString("tool.om.factory");
063        this.omFactory = (RetrieverFactory)Class.forName(className).newInstance();
064    }
065
066    /**
067     * Prepares tool for a single request
068     *
069     * @param data the initialization data
070     */
071    @Override
072    public void init(Object data)
073    {
074        // data = (RunData)data;
075    }
076
077    /**
078     * Implementation of ApplicationTool interface is not needed for this
079     * method as the tool is request scoped
080     */
081    @Override
082    public void refresh()
083    {
084        // empty
085    }
086
087    /**
088     * Inner class to present a nice interface to the template designer
089     */
090    protected class PullHelper
091    {
092        String omName;
093
094        protected PullHelper(String omName)
095        {
096            this.omName = omName;
097        }
098
099        public Object setKey(String key)
100            throws Exception
101        {
102            Object om = null;
103            String inputKey = omName + key;
104
105            if (omMap.containsKey(inputKey))
106            {
107                om = omMap.get(inputKey);
108            }
109            else
110            {
111                om = omFactory.getInstance(omName).retrieve(key);
112                omMap.put(inputKey, om);
113            }
114
115            return om;
116        }
117    }
118
119    /**
120     * Get the {@link PullHelper} object with the given name
121     * @param omName the object name
122     * @return the PullHelper
123     * @throws Exception if retrieving the object fails
124     */
125    public PullHelper get(String omName) throws Exception
126    {
127        PullHelper ph = pullMap.putIfAbsent(omName, new OMTool.PullHelper(omName));
128        if (ph == null)
129        {
130            return pullMap.get(omName);
131        }
132
133        return ph;
134    }
135
136    /**
137     * Get the object with the given name and key
138     * @param omName the object name
139     * @param key the object key
140     * @return the object
141     * @throws Exception if retrieving the object fails
142     */
143    public Object get(String omName, String key) throws Exception
144    {
145        return get(omName).setKey(key);
146    }
147
148    // ****************** Recyclable implementation ************************
149
150    private boolean disposed;
151
152    /**
153     * Recycles the object for a new client. Recycle methods with
154     * parameters must be added to implementing object and they will be
155     * automatically called by pool implementations when the object is
156     * taken from the pool for a new client. The parameters must
157     * correspond to the parameters of the constructors of the object.
158     * For new objects, constructors can call their corresponding recycle
159     * methods whenever applicable.
160     * The recycle methods must call their super.
161     */
162    @Override
163    public void recycle()
164    {
165        disposed = false;
166    }
167
168    /**
169     * Disposes the object after use. The method is called
170     * when the object is returned to its pool.
171     * The dispose method must call its super.
172     */
173    @Override
174    public void dispose()
175    {
176        omMap.clear();
177        disposed = true;
178    }
179
180    /**
181     * Checks whether the recyclable has been disposed.
182     * @return true, if the recyclable is disposed.
183     */
184    @Override
185    public boolean isDisposed()
186    {
187        return disposed;
188    }
189}