1 /*
   2  * Copyright (c) 2005, 2007, 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  */
  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<String>();
  38     static {
  39         // DeleteOnExitHook must be the last shutdown hook to be invoked.
  40         // Application shutdown hooks may add the first file to the
  41         // delete on exit list and cause the DeleteOnExitHook to be
  42         // registered during shutdown in progress. So set the
  43         // registerShutdownInProgress parameter to true.
  44         sun.misc.SharedSecrets.getJavaLangAccess()
  45             .registerShutdownHook(2 /* Shutdown hook invocation order */,
  46                 true /* register even if shutdown in progress */,
  47                 new Runnable() {
  48                     public void run() {
  49                        runHooks();
  50                     }
  51                 }
  52         );
  53     }
  54 
  55     private DeleteOnExitHook() {}
  56 
  57     static synchronized void add(String file) {
  58         if(files == null) {
  59             // DeleteOnExitHook is running. Too late to add a file
  60             throw new IllegalStateException("Shutdown in progress");
  61         }
  62 
  63         files.add(file);
  64     }
  65 
  66     static void runHooks() {
  67         LinkedHashSet<String> theFiles;
  68 
  69         synchronized (DeleteOnExitHook.class) {
  70             theFiles = files;
  71             files = null;
  72         }
  73 
  74         ArrayList<String> toBeDeleted = new ArrayList<String>(theFiles);
  75 
  76         // reverse the list to maintain previous jdk deletion order.
  77         // Last in first deleted.
  78         Collections.reverse(toBeDeleted);
  79         for (String filename : toBeDeleted) {
  80             (new File(filename)).delete();
  81         }
  82     }
  83 }