| /* |
| * Copyright 1999-2005 Sun Microsystems, Inc. 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. Sun designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| */ |
| |
| package java.lang; |
| |
| import java.util.ArrayList; |
| |
| |
| /** |
| * Package-private utility class containing data structures and logic |
| * governing the virtual-machine shutdown sequence. |
| * |
| * @author Mark Reinhold |
| * @since 1.3 |
| */ |
| |
| class Shutdown { |
| |
| /* Shutdown state */ |
| private static final int RUNNING = 0; |
| private static final int HOOKS = 1; |
| private static final int FINALIZERS = 2; |
| private static int state = RUNNING; |
| |
| /* Should we run all finalizers upon exit? */ |
| private static boolean runFinalizersOnExit = false; |
| |
| /* The set of registered, wrapped hooks, or null if there aren't any */ |
| private static ArrayList<Runnable> hooks = new ArrayList<Runnable>(); |
| |
| /* The preceding static fields are protected by this lock */ |
| private static class Lock { }; |
| private static Object lock = new Lock(); |
| |
| /* Lock object for the native halt method */ |
| private static Object haltLock = new Lock(); |
| |
| /* Invoked by Runtime.runFinalizersOnExit */ |
| static void setRunFinalizersOnExit(boolean run) { |
| synchronized (lock) { |
| runFinalizersOnExit = run; |
| } |
| } |
| |
| |
| /* Add a new shutdown hook. Checks the shutdown state and the hook itself, |
| * but does not do any security checks. |
| */ |
| static void add(Runnable hook) { |
| synchronized (lock) { |
| if (state > RUNNING) |
| throw new IllegalStateException("Shutdown in progress"); |
| |
| hooks.add(hook); |
| } |
| } |
| |
| |
| /* Remove a previously-registered hook. Like the add method, this method |
| * does not do any security checks. |
| */ |
| static boolean remove(Runnable hook) { |
| synchronized (lock) { |
| if (state > RUNNING) |
| throw new IllegalStateException("Shutdown in progress"); |
| if (hook == null) throw new NullPointerException(); |
| if (hooks == null) { |
| return false; |
| } else { |
| return hooks.remove(hook); |
| } |
| } |
| } |
| |
| |
| /* Run all registered shutdown hooks |
| */ |
| private static void runHooks() { |
| /* We needn't bother acquiring the lock just to read the hooks field, |
| * since the hooks can't be modified once shutdown is in progress |
| */ |
| for (Runnable hook : hooks) { |
| try { |
| hook.run(); |
| } catch(Throwable t) { |
| if (t instanceof ThreadDeath) { |
| ThreadDeath td = (ThreadDeath)t; |
| throw td; |
| } |
| } |
| } |
| } |
| |
| /* The halt method is synchronized on the halt lock |
| * to avoid corruption of the delete-on-shutdown file list. |
| * It invokes the true native halt method. |
| */ |
| static void halt(int status) { |
| synchronized (haltLock) { |
| halt0(status); |
| } |
| } |
| |
| static native void halt0(int status); |
| |
| /* Wormhole for invoking java.lang.ref.Finalizer.runAllFinalizers */ |
| private static native void runAllFinalizers(); |
| |
| |
| /* The actual shutdown sequence is defined here. |
| * |
| * If it weren't for runFinalizersOnExit, this would be simple -- we'd just |
| * run the hooks and then halt. Instead we need to keep track of whether |
| * we're running hooks or finalizers. In the latter case a finalizer could |
| * invoke exit(1) to cause immediate termination, while in the former case |
| * any further invocations of exit(n), for any n, simply stall. Note that |
| * if on-exit finalizers are enabled they're run iff the shutdown is |
| * initiated by an exit(0); they're never run on exit(n) for n != 0 or in |
| * response to SIGINT, SIGTERM, etc. |
| */ |
| private static void sequence() { |
| synchronized (lock) { |
| /* Guard against the possibility of a daemon thread invoking exit |
| * after DestroyJavaVM initiates the shutdown sequence |
| */ |
| if (state != HOOKS) return; |
| } |
| runHooks(); |
| boolean rfoe; |
| synchronized (lock) { |
| state = FINALIZERS; |
| rfoe = runFinalizersOnExit; |
| } |
| if (rfoe) runAllFinalizers(); |
| } |
| |
| |
| /* Invoked by Runtime.exit, which does all the security checks. |
| * Also invoked by handlers for system-provided termination events, |
| * which should pass a nonzero status code. |
| */ |
| static void exit(int status) { |
| boolean runMoreFinalizers = false; |
| synchronized (lock) { |
| if (status != 0) runFinalizersOnExit = false; |
| switch (state) { |
| case RUNNING: /* Initiate shutdown */ |
| state = HOOKS; |
| break; |
| case HOOKS: /* Stall and halt */ |
| break; |
| case FINALIZERS: |
| if (status != 0) { |
| /* Halt immediately on nonzero status */ |
| halt(status); |
| } else { |
| /* Compatibility with old behavior: |
| * Run more finalizers and then halt |
| */ |
| runMoreFinalizers = runFinalizersOnExit; |
| } |
| break; |
| } |
| } |
| if (runMoreFinalizers) { |
| runAllFinalizers(); |
| halt(status); |
| } |
| synchronized (Shutdown.class) { |
| /* Synchronize on the class object, causing any other thread |
| * that attempts to initiate shutdown to stall indefinitely |
| */ |
| sequence(); |
| halt(status); |
| } |
| } |
| |
| |
| /* Invoked by the JNI DestroyJavaVM procedure when the last non-daemon |
| * thread has finished. Unlike the exit method, this method does not |
| * actually halt the VM. |
| */ |
| static void shutdown() { |
| synchronized (lock) { |
| switch (state) { |
| case RUNNING: /* Initiate shutdown */ |
| state = HOOKS; |
| break; |
| case HOOKS: /* Stall and then return */ |
| case FINALIZERS: |
| break; |
| } |
| } |
| synchronized (Shutdown.class) { |
| sequence(); |
| } |
| } |
| |
| } |