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    /**
041     * The instance to use for the deprecated, static methods.
042     */
043    private static final FileCleaningTracker INSTANCE = new FileCleaningTracker();
044
045    /**
046     * Call this method to cause the file cleaner thread to terminate when
047     * there are no more objects being tracked for deletion.
048     * <p>
049     * In a simple environment, you don't need this method as the file cleaner
050     * thread will simply exit when the JVM exits. In a more complex environment,
051     * with multiple class loaders (such as an application server), you should be
052     * aware that the file cleaner thread will continue running even if the class
053     * loader it was started from terminates. This can constitute a memory leak.
054     * <p>
055     * For example, suppose that you have developed a web application, which
056     * contains the commons-io jar file in your WEB-INF/lib directory. In other
057     * words, the FileCleaner class is loaded through the class loader of your
058     * web application. If the web application is terminated, but the servlet
059     * container is still running, then the file cleaner thread will still exist,
060     * posing a memory leak.
061     * <p>
062     * This method allows the thread to be terminated. Simply call this method
063     * in the resource cleanup code, such as
064     * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)}.
065     * One called, no new objects can be tracked by the file cleaner.
066     * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
067     */
068    @Deprecated
069    public static synchronized void exitWhenFinished() {
070        INSTANCE.exitWhenFinished();
071    }
072
073    /**
074     * Gets the singleton instance, which is used by the deprecated, static methods.
075     * This is mainly useful for code, which wants to support the new
076     * {@link FileCleaningTracker} class while maintain compatibility with the
077     * deprecated {@link FileCleaner}.
078     *
079     * @return the singleton instance
080     */
081    public static FileCleaningTracker getInstance() {
082        return INSTANCE;
083    }
084
085    /**
086     * Gets the number of files currently being tracked, and therefore
087     * awaiting deletion.
088     *
089     * @return the number of files being tracked
090     * @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
091     */
092    @Deprecated
093    public static int getTrackCount() {
094        return INSTANCE.getTrackCount();
095    }
096
097    /**
098     * Track the specified file, using the provided marker, deleting the file
099     * when the marker instance is garbage collected.
100     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
101     *
102     * @param file  the file to be tracked, not null
103     * @param marker  the marker object used to track the file, not null
104     * @throws NullPointerException if the file is null
105     * @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
106     */
107    @Deprecated
108    public static void track(final File file, final Object marker) {
109        INSTANCE.track(file, marker);
110    }
111
112    /**
113     * Track the specified file, using the provided marker, deleting the file
114     * when the marker instance is garbage collected.
115     * The specified deletion strategy is used.
116     *
117     * @param file  the file to be tracked, not null
118     * @param marker  the marker object used to track the file, not null
119     * @param deleteStrategy  the strategy to delete the file, null means normal
120     * @throws NullPointerException if the file is null
121     * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
122     */
123    @Deprecated
124    public static void track(final File file, final Object marker, final FileDeleteStrategy deleteStrategy) {
125        INSTANCE.track(file, marker, deleteStrategy);
126    }
127
128    /**
129     * Track the specified file, using the provided marker, deleting the file
130     * when the marker instance is garbage collected.
131     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
132     *
133     * @param path  the full path to the file to be tracked, not null
134     * @param marker  the marker object used to track the file, not null
135     * @throws NullPointerException if the path is null
136     * @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
137     */
138    @Deprecated
139    public static void track(final String path, final Object marker) {
140        INSTANCE.track(path, marker);
141    }
142
143    /**
144     * Track the specified file, using the provided marker, deleting the file
145     * when the marker instance is garbage collected.
146     * The specified deletion strategy is used.
147     *
148     * @param path  the full path to the file to be tracked, not null
149     * @param marker  the marker object used to track the file, not null
150     * @param deleteStrategy  the strategy to delete the file, null means normal
151     * @throws NullPointerException if the path is null
152     * @deprecated Use {@link FileCleaningTracker#track(String, Object, FileDeleteStrategy)}.
153     */
154    @Deprecated
155    public static void track(final String path, final Object marker, final FileDeleteStrategy deleteStrategy) {
156        INSTANCE.track(path, marker, deleteStrategy);
157    }
158}