/*
 
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 
*
 
* This code is free software; you can redistribute it and/or modify it
 
* under the terms of the GNU General Public License version 2 only, as
 
* published by the Free Software Foundation.
  
Oracle designates this
 
* particular file as subject to the "Classpath" exception as provided
 
* by Oracle in the LICENSE file that accompanied this code.
 
*
 
* This code is distributed in the hope that it will be useful, but WITHOUT
 
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 
* FITNESS FOR A PARTICULAR PURPOSE.
  
See the GNU General Public License
 
* version 2 for more details (a copy is included in the LICENSE file that
 
* accompanied this code).
 
*
 
* You should have received a copy of the GNU General Public License version
 
* 2 along with this work; if not, write to the Free Software Foundation,
 
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 
*
 
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 
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*/
package java.io;

import java.util.*;
import java.io.File;

/**
 
* This class holds a set of filenames to be deleted on VM exit through a shutdown hook.
 
* A set is used both to prevent double-insertion of the same file as well as offer
 
* quick removal.
 
*/


class DeleteOnExitHook {
    
private static LinkedHashSet<String> files = new LinkedHashSet<>();
    
static {
        
// DeleteOnExitHook must be the last shutdown hook to be invoked.
        
// Application shutdown hooks may add the first file to the
        
// delete on exit list and cause the DeleteOnExitHook to be
        
// registered during shutdown in progress. So set the
        
// registerShutdownInProgress parameter to true.
        
sun.misc.SharedSecrets.getJavaLangAccess()
            
.registerShutdownHook(2 /* Shutdown hook invocation order */,
                
true /* register even if shutdown in progress */,
                
new Runnable() {
                    
public void run() {
                       
runHooks();
                    
}
                
}
        
);
    
}

    
private DeleteOnExitHook() {}

    
static synchronized void add(String file) {
        
if(files == null) {
            
// DeleteOnExitHook is running. Too late to add a file
            
throw new IllegalStateException("Shutdown in progress");
        
}

        
files.add(file);
    
}

    
static void runHooks() {
        
LinkedHashSet<String> theFiles;

        
synchronized (DeleteOnExitHook.class) {
            
theFiles = files;
            
files = null;
        
}

        
ArrayList<String> toBeDeleted = new ArrayList<>(theFiles);

        
// reverse the list to maintain previous jdk deletion order.
        
// Last in first deleted.
        
Collections.reverse(toBeDeleted);
        
for (String filename : toBeDeleted) {
            
(new File(filename)).delete();
        
}
    
}
}