/*
* Copyright (c) 1999, 2005, 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang;
import java.util.ArrayList;
import cli.System.AppDomain;
import cli.System.EventArgs;
import cli.System.EventHandler;
/**
* Package-private utility class containing data structures and logic
* governing the virtual-machine shutdown sequence.
*
* @author Mark Reinhold
* @since 1.3
*/
@ikvm.lang.Internal
public final 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? */
static volatile 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;
}
}
private static boolean initialized;
public static void init() {
synchronized (lock) {
if (initialized || state > RUNNING)
return;
initialized = true;
try
{
// AppDomain.ProcessExit has a LinkDemand, so we have to have a separate method
registerShutdownHook();
if (false) throw new cli.System.Security.SecurityException();
}
catch (cli.System.Security.SecurityException _)
{
}
// The order in with the hooks are added here is important as it
// determines the order in which they are run.
// (1)Console restore hook needs to be called first.
// (2)Application hooks must be run before calling deleteOnExitHook.
hooks.add(sun.misc.SharedSecrets.getJavaIOAccess().consoleRestoreHook());
hooks.add(ApplicationShutdownHooks.hook());
hooks.add(sun.misc.SharedSecrets.getJavaIODeleteOnExitAccess());
}
}
private static void registerShutdownHook()
{
AppDomain.get_CurrentDomain().add_ProcessExit(new EventHandler(new EventHandler.Method() {
public void Invoke(Object sender, EventArgs e) {
shutdown();
}
}));
}
/* 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");
init();
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 void halt0(int status) {
cli.System.Environment.Exit(status);
}
/* Wormhole for invoking java.lang.ref.Finalizer.runAllFinalizers */
private static void runAllFinalizers() { /* [IKVM] Don't need to do anything here */ }
/* 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();
}
}
}