1/*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements.  See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License.  You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17package org.apache.commons.io;
18
19import java.io.File;
20
21/**
22 * Keeps track of files awaiting deletion, and deletes them when an associated
23 * marker object is reclaimed by the garbage collector.
24 * <p>
25 * This utility creates a background thread to handle file deletion.
26 * Each file to be deleted is registered with a handler object.
27 * When the handler object is garbage collected, the file is deleted.
28 * <p>
29 * In an environment with multiple class loaders (a servlet container, for
30 * example), you should consider stopping the background thread if it is no
31 * longer needed. This is done by invoking the method
32 * {@link #exitWhenFinished}, typically in
33 * {@link javax.servlet.ServletContextListener#contextDestroyed} or similar.
34 *
35 * @author Noel Bergman
36 * @author Martin Cooper
37 * @version $Id: FileCleaner.java 553012 2007-07-03 23:01:07Z ggregory $
38 * @deprecated Use {@link FileCleaningTracker}
39 */
40public class FileCleaner {
41    /**
42     * The instance to use for the deprecated, static methods.
43     */
44    static final FileCleaningTracker theInstance = new FileCleaningTracker();
45
46    //-----------------------------------------------------------------------
47    /**
48     * Track the specified file, using the provided marker, deleting the file
49     * when the marker instance is garbage collected.
50     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
51     *
52     * @param file  the file to be tracked, not null
53     * @param marker  the marker object used to track the file, not null
54     * @throws NullPointerException if the file is null
55     * @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
56     */
57    public static void track(File file, Object marker) {
58        theInstance.track(file, marker);
59    }
60
61    /**
62     * Track the specified file, using the provided marker, deleting the file
63     * when the marker instance is garbage collected.
64     * The speified deletion strategy is used.
65     *
66     * @param file  the file to be tracked, not null
67     * @param marker  the marker object used to track the file, not null
68     * @param deleteStrategy  the strategy to delete the file, null means normal
69     * @throws NullPointerException if the file is null
70     * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
71     */
72    public static void track(File file, Object marker, FileDeleteStrategy deleteStrategy) {
73        theInstance.track(file, marker, deleteStrategy);
74    }
75
76    /**
77     * Track the specified file, using the provided marker, deleting the file
78     * when the marker instance is garbage collected.
79     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
80     *
81     * @param path  the full path to the file to be tracked, not null
82     * @param marker  the marker object used to track the file, not null
83     * @throws NullPointerException if the path is null
84     * @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
85     */
86    public static void track(String path, Object marker) {
87        theInstance.track(path, marker);
88    }
89
90    /**
91     * Track the specified file, using the provided marker, deleting the file
92     * when the marker instance is garbage collected.
93     * The speified deletion strategy is used.
94     *
95     * @param path  the full path to the file to be tracked, not null
96     * @param marker  the marker object used to track the file, not null
97     * @param deleteStrategy  the strategy to delete the file, null means normal
98     * @throws NullPointerException if the path is null
99     * @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}
155