001    /**
002     *
003     * Copyright 2005 The Apache Software Foundation
004     *
005     *  Licensed under the Apache License, Version 2.0 (the "License");
006     *  you may not use this file except in compliance with the License.
007     *  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    
018    package org.apache.geronimo.kernel.config;
019    
020    import java.net.URI;
021    import java.net.URL;
022    import java.net.URLClassLoader;
023    import java.io.ObjectInputStream;
024    import java.io.ObjectOutputStream;
025    import java.io.ObjectStreamClass;
026    import java.util.Map;
027    import java.lang.reflect.Field;
028    
029    import org.apache.commons.logging.LogFactory;
030    
031    /**
032     *
033     * @version $Rev: 428082 $ $Date: 2006-08-02 11:35:10 -0700 (Wed, 02 Aug 2006) $
034     */
035    public class ConfigurationClassLoader extends URLClassLoader {
036        private final URI id;
037        
038        public ConfigurationClassLoader(URI id, URL[] urls, ClassLoader parent) {
039            super(urls, parent);
040            this.id = id;
041        }
042        
043        public URI getID() {
044            return id;
045        }
046    
047        public void destroy() {
048            LogFactory.release(this);
049            clearSoftCache(ObjectInputStream.class, "subclassAudits");
050            clearSoftCache(ObjectOutputStream.class, "subclassAudits");
051            clearSoftCache(ObjectStreamClass.class, "localDescs");
052            clearSoftCache(ObjectStreamClass.class, "reflectors");
053        }
054    
055        public String toString() {
056            return "[Configuration ClassLoader id=" + id + "]";
057        }
058    
059        private static Object lock = new Object();
060        private static boolean clearSoftCacheFailed = false;
061        private static void clearSoftCache(Class clazz, String fieldName) {
062            Map cache = null;
063            try {
064                Field f = clazz.getDeclaredField(fieldName);
065                f.setAccessible(true);
066                cache = (Map) f.get(null);
067            } catch (Throwable e) {
068                synchronized (lock) {
069                    if (!clearSoftCacheFailed) {
070                        clearSoftCacheFailed = true;
071                        LogFactory.getLog(ConfigurationClassLoader.class).debug("Unable to clear SoftCache field " + fieldName + " in class " + clazz);
072                    }
073                }
074            }
075    
076            if (cache != null) {
077                synchronized (cache) {
078                    cache.clear();
079                }
080            }
081        }
082    }