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 */
017package org.apache.commons.io;
018
019import 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 * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)} or similar.
034 *
035 * @deprecated Use {@link FileCleaningTracker}
036 */
037@Deprecated
038public class FileCleaner {
039    /**
040     * The instance to use for the deprecated, static methods.
041     */
042    static final FileCleaningTracker theInstance = new FileCleaningTracker();
043
044    /**
045     * Track the specified file, using the provided marker, deleting the file
046     * when the marker instance is garbage collected.
047     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
048     *
049     * @param file  the file to be tracked, not null
050     * @param marker  the marker object used to track the file, not null
051     * @throws NullPointerException if the file is null
052     * @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
053     */
054    @Deprecated
055    public static void track(final File file, final Object marker) {
056        theInstance.track(file, marker);
057    }
058
059    /**
060     * Track the specified file, using the provided marker, deleting the file
061     * when the marker instance is garbage collected.
062     * The specified deletion strategy is used.
063     *
064     * @param file  the file to be tracked, not null
065     * @param marker  the marker object used to track the file, not null
066     * @param deleteStrategy  the strategy to delete the file, null means normal
067     * @throws NullPointerException if the file is null
068     * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
069     */
070    @Deprecated
071    public static void track(final File file, final Object marker, final FileDeleteStrategy deleteStrategy) {
072        theInstance.track(file, marker, deleteStrategy);
073    }
074
075    /**
076     * Track the specified file, using the provided marker, deleting the file
077     * when the marker instance is garbage collected.
078     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
079     *
080     * @param path  the full path to the file to be tracked, not null
081     * @param marker  the marker object used to track the file, not null
082     * @throws NullPointerException if the path is null
083     * @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
084     */
085    @Deprecated
086    public static void track(final String path, final 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 specified 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    @Deprecated
102    public static void track(final String path, final Object marker, final FileDeleteStrategy deleteStrategy) {
103        theInstance.track(path, marker, deleteStrategy);
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    @Deprecated
114    public static int getTrackCount() {
115        return theInstance.getTrackCount();
116    }
117
118    /**
119     * Call this method to cause the file cleaner thread to terminate when
120     * there are no more objects being tracked for deletion.
121     * <p>
122     * In a simple environment, you don't need this method as the file cleaner
123     * thread will simply exit when the JVM exits. In a more complex environment,
124     * with multiple class loaders (such as an application server), you should be
125     * aware that the file cleaner thread will continue running even if the class
126     * loader it was started from terminates. This can constitute a memory leak.
127     * <p>
128     * For example, suppose that you have developed a web application, which
129     * contains the commons-io jar file in your WEB-INF/lib directory. In other
130     * words, the FileCleaner class is loaded through the class loader of your
131     * web application. If the web application is terminated, but the servlet
132     * container is still running, then the file cleaner thread will still exist,
133     * posing a memory leak.
134     * <p>
135     * This method allows the thread to be terminated. Simply call this method
136     * in the resource cleanup code, such as
137     * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)}.
138     * One called, no new objects can be tracked by the file cleaner.
139     * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
140     */
141    @Deprecated
142    public static synchronized void exitWhenFinished() {
143        theInstance.exitWhenFinished();
144    }
145
146    /**
147     * Returns the singleton instance, which is used by the deprecated, static methods.
148     * This is mainly useful for code, which wants to support the new
149     * {@link FileCleaningTracker} class while maintain compatibility with the
150     * deprecated {@link FileCleaner}.
151     *
152     * @return the singleton instance
153     */
154    public static FileCleaningTracker getInstance() {
155        return theInstance;
156    }
157}