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 *      https://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     *
067     * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
068     */
069    @Deprecated
070    public static synchronized void exitWhenFinished() {
071        INSTANCE.exitWhenFinished();
072    }
073
074    /**
075     * Gets the singleton instance, which is used by the deprecated, static methods.
076     * This is mainly useful for code, which wants to support the new
077     * {@link FileCleaningTracker} class while maintain compatibility with the
078     * deprecated {@link FileCleaner}.
079     *
080     * @return the singleton instance.
081     */
082    public static FileCleaningTracker getInstance() {
083        return INSTANCE;
084    }
085
086    /**
087     * Gets the number of files currently being tracked, and therefore
088     * awaiting deletion.
089     *
090     * @return the number of files being tracked.
091     * @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
092     */
093    @Deprecated
094    public static int getTrackCount() {
095        return INSTANCE.getTrackCount();
096    }
097
098    /**
099     * Track the specified file, using the provided marker, deleting the file
100     * when the marker instance is garbage collected.
101     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
102     *
103     * @param file  the file to be tracked, not null.
104     * @param marker  the marker object used to track the file, not null.
105     * @throws NullPointerException if the file is null.
106     * @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
107     */
108    @Deprecated
109    public static void track(final File file, final Object marker) {
110        INSTANCE.track(file, marker);
111    }
112
113    /**
114     * Track the specified file, using the provided marker, deleting the file
115     * when the marker instance is garbage collected.
116     * The specified deletion strategy is used.
117     *
118     * @param file  the file to be tracked, not null.
119     * @param marker  the marker object used to track the file, not null.
120     * @param deleteStrategy  the strategy to delete the file, null means normal.
121     * @throws NullPointerException if the file is null.
122     * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
123     */
124    @Deprecated
125    public static void track(final File file, final Object marker, final FileDeleteStrategy deleteStrategy) {
126        INSTANCE.track(file, marker, deleteStrategy);
127    }
128
129    /**
130     * Track the specified file, using the provided marker, deleting the file
131     * when the marker instance is garbage collected.
132     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
133     *
134     * @param path  the full path to the file to be tracked, not null.
135     * @param marker  the marker object used to track the file, not null.
136     * @throws NullPointerException if the path is null.
137     * @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
138     */
139    @Deprecated
140    public static void track(final String path, final Object marker) {
141        INSTANCE.track(path, marker);
142    }
143
144    /**
145     * Track the specified file, using the provided marker, deleting the file
146     * when the marker instance is garbage collected.
147     * The specified deletion strategy is used.
148     *
149     * @param path  the full path to the file to be tracked, not null.
150     * @param marker  the marker object used to track the file, not null.
151     * @param deleteStrategy  the strategy to delete the file, null means normal.
152     * @throws NullPointerException if the path is null.
153     * @deprecated Use {@link FileCleaningTracker#track(String, Object, FileDeleteStrategy)}.
154     */
155    @Deprecated
156    public static void track(final String path, final Object marker, final FileDeleteStrategy deleteStrategy) {
157        INSTANCE.track(path, marker, deleteStrategy);
158    }
159
160    /**
161     * Construct a new instance.
162     */
163    public FileCleaner() {
164        // empty
165    }
166}