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.io;
018    
019    import java.io.File;
020    
021    /**
022     * Keeps track of files awaiting deletion, and deletes them when an associated
023     * marker object is reclaimed by the garbage collector.
024     * <p>
025     * This utility creates a background thread to handle file deletion.
026     * Each file to be deleted is registered with a handler object.
027     * When the handler object is garbage collected, the file is deleted.
028     * <p>
029     * In an environment with multiple class loaders (a servlet container, for
030     * example), you should consider stopping the background thread if it is no
031     * longer needed. This is done by invoking the method
032     * {@link #exitWhenFinished}, typically in
033     * {@link javax.servlet.ServletContextListener#contextDestroyed} or similar.
034     *
035     * @author Noel Bergman
036     * @author Martin Cooper
037     * @version $Id: FileCleaner.java 553012 2007-07-03 23:01:07Z ggregory $
038     * @deprecated Use {@link FileCleaningTracker}
039     */
040    public class FileCleaner {
041        /**
042         * The instance to use for the deprecated, static methods.
043         */
044        static final FileCleaningTracker theInstance = new FileCleaningTracker();
045    
046        //-----------------------------------------------------------------------
047        /**
048         * Track the specified file, using the provided marker, deleting the file
049         * when the marker instance is garbage collected.
050         * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
051         *
052         * @param file  the file to be tracked, not null
053         * @param marker  the marker object used to track the file, not null
054         * @throws NullPointerException if the file is null
055         * @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
056         */
057        public static void track(File file, Object marker) {
058            theInstance.track(file, marker);
059        }
060    
061        /**
062         * Track the specified file, using the provided marker, deleting the file
063         * when the marker instance is garbage collected.
064         * The speified deletion strategy is used.
065         *
066         * @param file  the file to be tracked, not null
067         * @param marker  the marker object used to track the file, not null
068         * @param deleteStrategy  the strategy to delete the file, null means normal
069         * @throws NullPointerException if the file is null
070         * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
071         */
072        public static void track(File file, Object marker, FileDeleteStrategy deleteStrategy) {
073            theInstance.track(file, marker, deleteStrategy);
074        }
075    
076        /**
077         * Track the specified file, using the provided marker, deleting the file
078         * when the marker instance is garbage collected.
079         * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
080         *
081         * @param path  the full path to the file to be tracked, not null
082         * @param marker  the marker object used to track the file, not null
083         * @throws NullPointerException if the path is null
084         * @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
085         */
086        public static void track(String path, Object marker) {
087            theInstance.track(path, marker);
088        }
089    
090        /**
091         * Track the specified file, using the provided marker, deleting the file
092         * when the marker instance is garbage collected.
093         * The speified deletion strategy is used.
094         *
095         * @param path  the full path to the file to be tracked, not null
096         * @param marker  the marker object used to track the file, not null
097         * @param deleteStrategy  the strategy to delete the file, null means normal
098         * @throws NullPointerException if the path is null
099         * @deprecated Use {@link FileCleaningTracker#track(String, Object, FileDeleteStrategy)}.
100         */
101        public static void track(String path, Object marker, FileDeleteStrategy deleteStrategy) {
102            theInstance.track(path, marker, deleteStrategy);
103        }
104    
105        //-----------------------------------------------------------------------
106        /**
107         * Retrieve the number of files currently being tracked, and therefore
108         * awaiting deletion.
109         *
110         * @return the number of files being tracked
111         * @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
112         */
113        public static int getTrackCount() {
114            return theInstance.getTrackCount();
115        }
116    
117        /**
118         * Call this method to cause the file cleaner thread to terminate when
119         * there are no more objects being tracked for deletion.
120         * <p>
121         * In a simple environment, you don't need this method as the file cleaner
122         * thread will simply exit when the JVM exits. In a more complex environment,
123         * with multiple class loaders (such as an application server), you should be
124         * aware that the file cleaner thread will continue running even if the class
125         * loader it was started from terminates. This can consitute a memory leak.
126         * <p>
127         * For example, suppose that you have developed a web application, which
128         * contains the commons-io jar file in your WEB-INF/lib directory. In other
129         * words, the FileCleaner class is loaded through the class loader of your
130         * web application. If the web application is terminated, but the servlet
131         * container is still running, then the file cleaner thread will still exist,
132         * posing a memory leak.
133         * <p>
134         * This method allows the thread to be terminated. Simply call this method
135         * in the resource cleanup code, such as {@link javax.servlet.ServletContextListener#contextDestroyed}.
136         * One called, no new objects can be tracked by the file cleaner.
137         * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
138         */
139        public static synchronized void exitWhenFinished() {
140            theInstance.exitWhenFinished();
141        }
142    
143        /**
144         * Returns the singleton instance, which is used by the deprecated, static methods.
145         * This is mainly useful for code, which wants to support the new
146         * {@link FileCleaningTracker} class while maintain compatibility with the
147         * deprecated {@link FileCleaner}.
148         * 
149         * @return the singleton instance
150         */
151        public static FileCleaningTracker getInstance() {
152            return theInstance;
153        }
154    }