jdk/src/share/classes/java/io/DeleteOnExitHook.java
author mchung
Mon, 27 Apr 2009 12:08:41 -0700
changeset 2703 acd4d6a53e3e
parent 2277 445a331b4a8b
child 5506 202f599c92aa
permissions -rw-r--r--
6829503: addShutdownHook fails if called after shutdown has commenced. Summary: allow shutdown hook to be added during shutdown and handle properly if it fails to add Reviewed-by: alanb, dholmes, martin
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/*
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 * Copyright 2005-2007 Sun Microsystems, Inc.  All Rights Reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.  Sun designates this
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 * particular file as subject to the "Classpath" exception as provided
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 * by Sun in the LICENSE file that accompanied this code.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 * CA 95054 USA or visit www.sun.com if you need additional information or
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 * have any questions.
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 */
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package java.io;
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import java.util.*;
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import java.io.File;
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/**
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 * This class holds a set of filenames to be deleted on VM exit through a shutdown hook.
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 * A set is used both to prevent double-insertion of the same file as well as offer
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 * quick removal.
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 */
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class DeleteOnExitHook {
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    private static LinkedHashSet<String> files = new LinkedHashSet<String>();
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    static {
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        // DeleteOnExitHook must be the last shutdown hook to be invoked.
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        // Application shutdown hooks may add the first file to the
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        // delete on exit list and cause the DeleteOnExitHook to be
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        // registered during shutdown in progress. So set the
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        // registerShutdownInProgress parameter to true.
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        sun.misc.SharedSecrets.getJavaLangAccess()
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            .registerShutdownHook(2 /* Shutdown hook invocation order */,
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                true /* register even if shutdown in progress */,
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                new Runnable() {
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                    public void run() {
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                       runHooks();
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                    }
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                }
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        );
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    }
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    private DeleteOnExitHook() {}
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    static synchronized void add(String file) {
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        if(files == null) {
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            // DeleteOnExitHook is running. Too late to add a file
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            throw new IllegalStateException("Shutdown in progress");
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        }
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        files.add(file);
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    }
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    static void runHooks() {
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        LinkedHashSet<String> theFiles;
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        synchronized (DeleteOnExitHook.class) {
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            theFiles = files;
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            files = null;
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        }
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        ArrayList<String> toBeDeleted = new ArrayList<String>(theFiles);
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        // reverse the list to maintain previous jdk deletion order.
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        // Last in first deleted.
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        Collections.reverse(toBeDeleted);
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        for (String filename : toBeDeleted) {
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            (new File(filename)).delete();
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        }
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    }
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}