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;
29import jdk.internal.misc.SharedSecrets;
30
31/**
32 * This class holds a set of filenames to be deleted on VM exit through a shutdown hook.
33 * A set is used both to prevent double-insertion of the same file as well as offer
34 * quick removal.
35 */
36
37class DeleteOnExitHook {
38    private static LinkedHashSet<String> files = new LinkedHashSet<>();
39    static {
40        // DeleteOnExitHook must be the last shutdown hook to be invoked.
41        // Application shutdown hooks may add the first file to the
42        // delete on exit list and cause the DeleteOnExitHook to be
43        // registered during shutdown in progress. So set the
44        // registerShutdownInProgress parameter to true.
45        SharedSecrets.getJavaLangAccess()
46            .registerShutdownHook(2 /* Shutdown hook invocation order */,
47                true /* register even if shutdown in progress */,
48                new Runnable() {
49                    public void run() {
50                       runHooks();
51                    }
52                }
53        );
54    }
55
56    private DeleteOnExitHook() {}
57
58    static synchronized void add(String file) {
59        if(files == null) {
60            // DeleteOnExitHook is running. Too late to add a file
61            throw new IllegalStateException("Shutdown in progress");
62        }
63
64        files.add(file);
65    }
66
67    static void runHooks() {
68        LinkedHashSet<String> theFiles;
69
70        synchronized (DeleteOnExitHook.class) {
71            theFiles = files;
72            files = null;
73        }
74
75        ArrayList<String> toBeDeleted = new ArrayList<>(theFiles);
76
77        // reverse the list to maintain previous jdk deletion order.
78        // Last in first deleted.
79        Collections.reverse(toBeDeleted);
80        for (String filename : toBeDeleted) {
81            (new File(filename)).delete();
82        }
83    }
84}
85