1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
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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
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24  */
25 package java.io;
26 
27 import java.util.*;
28 import 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 
36 class 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 
DeleteOnExitHook()46     private DeleteOnExitHook() {}
47 
add(String file)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 
runHooks()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