285 lines
10 KiB
Java
285 lines
10 KiB
Java
/*
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* Copyright (c) 1999, 2005, Oracle and/or its affiliates. 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. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang;
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import cli.System.AppDomain;
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import cli.System.EventArgs;
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import cli.System.EventHandler;
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import cli.System.Threading.Monitor;
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/**
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* Package-private utility class containing data structures and logic
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* governing the virtual-machine shutdown sequence.
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*
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* @author Mark Reinhold
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* @since 1.3
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*/
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class Shutdown {
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/* Shutdown state */
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private static final int RUNNING = 0;
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private static final int HOOKS = 1;
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private static final int FINALIZERS = 2;
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private static int state = RUNNING;
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/* Should we run all finalizers upon exit? */
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static volatile boolean runFinalizersOnExit = false;
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// The system shutdown hooks are registered with a predefined slot.
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// The list of shutdown hooks is as follows:
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// (0) Console restore hook
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// (1) Application hooks
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// (2) DeleteOnExit hook
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private static final int MAX_SYSTEM_HOOKS = 10;
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private static final Runnable[] hooks = new Runnable[MAX_SYSTEM_HOOKS];
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// the index of the currently running shutdown hook to the hooks array
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private static int currentRunningHook = 0;
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// [IKVM] have we registered the AppDomain.ProcessExit event handler?
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private static boolean registeredProcessExit;
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/* The preceding static fields are protected by this lock */
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private static class Lock { };
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private static Object lock = new Lock();
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/* Lock object for the native halt method */
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private static Object haltLock = new Lock();
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/* Invoked by Runtime.runFinalizersOnExit */
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static void setRunFinalizersOnExit(boolean run) {
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synchronized (lock) {
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runFinalizersOnExit = run;
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}
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}
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private static void registerProcessExit() {
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try {
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// MONOBUG Mono doesn't support starting a new thread during ProcessExit
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// (and application shutdown hooks are based on threads)
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// see https://bugzilla.xamarin.com/show_bug.cgi?id=5650
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if (!ikvm.internal.Util.MONO) {
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// AppDomain.ProcessExit has a LinkDemand, so we have to have a separate method
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registerShutdownHook();
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if (false) throw new cli.System.Security.SecurityException();
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}
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}
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catch (cli.System.Security.SecurityException _) {
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}
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}
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private static void registerShutdownHook()
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{
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AppDomain.get_CurrentDomain().add_ProcessExit(new EventHandler(new EventHandler.Method() {
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public void Invoke(Object sender, EventArgs e) {
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shutdown();
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}
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}));
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}
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/**
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* Add a new shutdown hook. Checks the shutdown state and the hook itself,
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* but does not do any security checks.
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*
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* The registerShutdownInProgress parameter should be false except
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* registering the DeleteOnExitHook since the first file may
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* be added to the delete on exit list by the application shutdown
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* hooks.
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*
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* @params slot the slot in the shutdown hook array, whose element
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* will be invoked in order during shutdown
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* @params registerShutdownInProgress true to allow the hook
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* to be registered even if the shutdown is in progress.
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* @params hook the hook to be registered
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*
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* @throw IllegalStateException
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* if registerShutdownInProgress is false and shutdown is in progress; or
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* if registerShutdownInProgress is true and the shutdown process
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* already passes the given slot
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*/
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static void add(int slot, boolean registerShutdownInProgress, Runnable hook) {
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synchronized (lock) {
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if (hooks[slot] != null)
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throw new InternalError("Shutdown hook at slot " + slot + " already registered");
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if (!registerShutdownInProgress) {
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if (state > RUNNING)
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throw new IllegalStateException("Shutdown in progress");
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} else {
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if (state > HOOKS || (state == HOOKS && slot <= currentRunningHook))
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throw new IllegalStateException("Shutdown in progress");
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}
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if (!registeredProcessExit) {
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registeredProcessExit = true;
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registerProcessExit();
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}
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hooks[slot] = hook;
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}
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}
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/* Run all registered shutdown hooks
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*/
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private static void runHooks() {
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for (int i=0; i < MAX_SYSTEM_HOOKS; i++) {
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try {
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Runnable hook;
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synchronized (lock) {
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// acquire the lock to make sure the hook registered during
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// shutdown is visible here.
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currentRunningHook = i;
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hook = hooks[i];
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}
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if (hook != null) hook.run();
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} catch(Throwable t) {
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if (t instanceof ThreadDeath) {
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ThreadDeath td = (ThreadDeath)t;
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throw td;
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}
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}
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}
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}
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/* The halt method is synchronized on the halt lock
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* to avoid corruption of the delete-on-shutdown file list.
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* It invokes the true native halt method.
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*/
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static void halt(int status) {
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synchronized (haltLock) {
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halt0(status);
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}
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}
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static void halt0(int status) {
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cli.System.Environment.Exit(status);
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}
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/* Wormhole for invoking java.lang.ref.Finalizer.runAllFinalizers */
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private static void runAllFinalizers() { /* [IKVM] Don't need to do anything here */ }
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/* The actual shutdown sequence is defined here.
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*
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* If it weren't for runFinalizersOnExit, this would be simple -- we'd just
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* run the hooks and then halt. Instead we need to keep track of whether
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* we're running hooks or finalizers. In the latter case a finalizer could
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* invoke exit(1) to cause immediate termination, while in the former case
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* any further invocations of exit(n), for any n, simply stall. Note that
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* if on-exit finalizers are enabled they're run iff the shutdown is
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* initiated by an exit(0); they're never run on exit(n) for n != 0 or in
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* response to SIGINT, SIGTERM, etc.
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*/
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private static void sequence() {
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synchronized (lock) {
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/* Guard against the possibility of a daemon thread invoking exit
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* after DestroyJavaVM initiates the shutdown sequence
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*/
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if (state != HOOKS) return;
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}
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runHooks();
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boolean rfoe;
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synchronized (lock) {
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state = FINALIZERS;
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rfoe = runFinalizersOnExit;
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}
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if (rfoe) runAllFinalizers();
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}
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/* Invoked by Runtime.exit, which does all the security checks.
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* Also invoked by handlers for system-provided termination events,
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* which should pass a nonzero status code.
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*/
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static void exit(int status) {
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boolean runMoreFinalizers = false;
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synchronized (lock) {
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if (status != 0) runFinalizersOnExit = false;
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switch (state) {
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case RUNNING: /* Initiate shutdown */
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state = HOOKS;
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break;
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case HOOKS: /* Stall and halt */
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break;
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case FINALIZERS:
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if (status != 0) {
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/* Halt immediately on nonzero status */
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halt(status);
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} else {
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/* Compatibility with old behavior:
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* Run more finalizers and then halt
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*/
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runMoreFinalizers = runFinalizersOnExit;
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}
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break;
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}
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}
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if (runMoreFinalizers) {
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runAllFinalizers();
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halt(status);
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}
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synchronized (Shutdown.class) {
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/* Synchronize on the class object, causing any other thread
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* that attempts to initiate shutdown to stall indefinitely
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*/
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sequence();
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halt(status);
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}
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}
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/* Invoked by the JNI DestroyJavaVM procedure when the last non-daemon
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* thread has finished. Unlike the exit method, this method does not
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* actually halt the VM.
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*/
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static void shutdown() {
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synchronized (lock) {
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switch (state) {
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case RUNNING: /* Initiate shutdown */
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state = HOOKS;
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break;
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case HOOKS: /* Stall and then return */
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case FINALIZERS:
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break;
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}
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}
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// [IKVM] We don't block here, because we're being called
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// from the AppDomain.ProcessExit event and we don't want to
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// deadlock with the thread that called exit.
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// Note that our JNI DestroyJavaVM implementation doesn't
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// call this method.
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if (Monitor.TryEnter(Shutdown.class)) {
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try {
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sequence();
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} finally {
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Monitor.Exit(Shutdown.class);
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}
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}
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}
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}
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