J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2005-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | package java.lang; |
| 26 | |
| 27 | import java.util.*; |
| 28 | |
| 29 | /* |
| 30 | * Class to track and run user level shutdown hooks registered through |
| 31 | * <tt>{@link Runtime#addShutdownHook Runtime.addShutdownHook}</tt>. |
| 32 | * |
| 33 | * @see java.lang.Runtime#addShutdownHook |
| 34 | * @see java.lang.Runtime#removeShutdownHook |
| 35 | */ |
| 36 | |
| 37 | class ApplicationShutdownHooks implements Runnable { |
| 38 | private static ApplicationShutdownHooks instance = null; |
| 39 | |
| 40 | /* The set of registered hooks */ |
| 41 | private static IdentityHashMap<Thread, Thread> hooks = new IdentityHashMap<Thread, Thread>(); |
| 42 | |
| 43 | static synchronized ApplicationShutdownHooks hook() { |
| 44 | if (instance == null) |
| 45 | instance = new ApplicationShutdownHooks(); |
| 46 | |
| 47 | return instance; |
| 48 | } |
| 49 | |
| 50 | private ApplicationShutdownHooks() {} |
| 51 | |
| 52 | /* Add a new shutdown hook. Checks the shutdown state and the hook itself, |
| 53 | * but does not do any security checks. |
| 54 | */ |
| 55 | static synchronized void add(Thread hook) { |
| 56 | if(hooks == null) |
| 57 | throw new IllegalStateException("Shutdown in progress"); |
| 58 | |
| 59 | if (hook.isAlive()) |
| 60 | throw new IllegalArgumentException("Hook already running"); |
| 61 | |
| 62 | if (hooks.containsKey(hook)) |
| 63 | throw new IllegalArgumentException("Hook previously registered"); |
| 64 | |
| 65 | hooks.put(hook, hook); |
| 66 | } |
| 67 | |
| 68 | /* Remove a previously-registered hook. Like the add method, this method |
| 69 | * does not do any security checks. |
| 70 | */ |
| 71 | static synchronized boolean remove(Thread hook) { |
| 72 | if(hooks == null) |
| 73 | throw new IllegalStateException("Shutdown in progress"); |
| 74 | |
| 75 | if (hook == null) |
| 76 | throw new NullPointerException(); |
| 77 | |
| 78 | return hooks.remove(hook) != null; |
| 79 | } |
| 80 | |
| 81 | /* Iterates over all application hooks creating a new thread for each |
| 82 | * to run in. Hooks are run concurrently and this method waits for |
| 83 | * them to finish. |
| 84 | */ |
| 85 | public void run() { |
| 86 | Collection<Thread> threads; |
| 87 | synchronized(ApplicationShutdownHooks.class) { |
| 88 | threads = hooks.keySet(); |
| 89 | hooks = null; |
| 90 | } |
| 91 | |
| 92 | for (Thread hook : threads) { |
| 93 | hook.start(); |
| 94 | } |
| 95 | for (Thread hook : threads) { |
| 96 | try { |
| 97 | hook.join(); |
| 98 | } catch (InterruptedException x) { } |
| 99 | } |
| 100 | } |
| 101 | } |