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 * https://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 *
67 * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
68 */
69 @Deprecated
70 public static synchronized void exitWhenFinished() {
71 INSTANCE.exitWhenFinished();
72 }
73
74 /**
75 * Gets the singleton instance, which is used by the deprecated, static methods.
76 * This is mainly useful for code, which wants to support the new
77 * {@link FileCleaningTracker} class while maintain compatibility with the
78 * deprecated {@link FileCleaner}.
79 *
80 * @return the singleton instance.
81 */
82 public static FileCleaningTracker getInstance() {
83 return INSTANCE;
84 }
85
86 /**
87 * Gets the number of files currently being tracked, and therefore
88 * awaiting deletion.
89 *
90 * @return the number of files being tracked.
91 * @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
92 */
93 @Deprecated
94 public static int getTrackCount() {
95 return INSTANCE.getTrackCount();
96 }
97
98 /**
99 * 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 }