DeleteOnExitHook.java revision 552ce337c6777082f434e4f1696ef02a13d5402a 
1/*
2 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25package java.io;
26
27import java.util.*;
28import java.io.File;
29
30/**
31 * This class holds a set of filenames to be deleted on VM exit through a shutdown hook.
32 * A set is used both to prevent double-insertion of the same file as well as offer
33 * quick removal.
34 */
35
36class DeleteOnExitHook {
37    private static LinkedHashSet<String> files = new LinkedHashSet<>();
38    static {
39        Runtime.getRuntime().addShutdownHook(new Thread() {
40            public void run() {
41                runHooks();
42            }
43        });
44    }
45
46    private DeleteOnExitHook() {}
47
48    static synchronized void add(String file) {
49        if(files == null) {
50            // DeleteOnExitHook is running. Too late to add a file
51            throw new IllegalStateException("Shutdown in progress");
52        }
53
54        files.add(file);
55    }
56
57    static void runHooks() {
58        LinkedHashSet<String> theFiles;
59
60        synchronized (DeleteOnExitHook.class) {
61            theFiles = files;
62            files = null;
63        }
64
65        ArrayList<String> toBeDeleted = new ArrayList<>(theFiles);
66
67        // reverse the list to maintain previous jdk deletion order.
68        // Last in first deleted.
69        Collections.reverse(toBeDeleted);
70        for (String filename : toBeDeleted) {
71            (new File(filename)).delete();
72        }
73    }
74}
75