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 */
17 package org.apache.commons.io;
18
19 import 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 * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)} or similar.
34 *
35 * @deprecated Use {@link FileCleaningTracker}
36 */
37 @Deprecated
38 public class FileCleaner {
39
40 /**
41 * The instance to use for the deprecated, static methods.
42 */
43 private static final FileCleaningTracker INSTANCE = new FileCleaningTracker();
44
45 /**
46 * Call this method to cause the file cleaner thread to terminate when
47 * there are no more objects being tracked for deletion.
48 * <p>
49 * In a simple environment, you don't need this method as the file cleaner
50 * thread will simply exit when the JVM exits. In a more complex environment,
51 * with multiple class loaders (such as an application server), you should be
52 * aware that the file cleaner thread will continue running even if the class
53 * loader it was started from terminates. This can constitute a memory leak.
54 * <p>
55 * For example, suppose that you have developed a web application, which
56 * contains the commons-io jar file in your WEB-INF/lib directory. In other
57 * words, the FileCleaner class is loaded through the class loader of your
58 * web application. If the web application is terminated, but the servlet
59 * container is still running, then the file cleaner thread will still exist,
60 * posing a memory leak.
61 * <p>
62 * This method allows the thread to be terminated. Simply call this method
63 * in the resource cleanup code, such as
64 * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)}.
65 * One called, no new objects can be tracked by the file cleaner.
66 * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
67 */
68 @Deprecated
69 public static synchronized void exitWhenFinished() {
70 INSTANCE.exitWhenFinished();
71 }
72
73 /**
74 * Gets the singleton instance, which is used by the deprecated, static methods.
75 * This is mainly useful for code, which wants to support the new
76 * {@link FileCleaningTracker} class while maintain compatibility with the
77 * deprecated {@link FileCleaner}.
78 *
79 * @return the singleton instance
80 */
81 public static FileCleaningTracker getInstance() {
82 return INSTANCE;
83 }
84
85 /**
86 * Gets the number of files currently being tracked, and therefore
87 * awaiting deletion.
88 *
89 * @return the number of files being tracked
90 * @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
91 */
92 @Deprecated
93 public static int getTrackCount() {
94 return INSTANCE.getTrackCount();
95 }
96
97 /**
98 * Track the specified file, using the provided marker, deleting the file
99 * 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
159 /**
160 * Construct a new instance.
161 */
162 public FileCleaner() {
163 // empty
164 }
165 }