| /* |
| * Copyright (c) 1999, 2018, 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 jdk.internal.misc.VM; |
| |
| /** |
| * Package-private utility class containing data structures and logic |
| * governing the virtual-machine shutdown sequence. |
| * |
| * @author Mark Reinhold |
| * @since 1.3 |
| * |
| * @see java.io.Console |
| * @see ApplicationShutdownHooks |
| * @see java.io.DeleteOnExitHook |
| */ |
| |
| class Shutdown { |
| |
| // The system shutdown hooks are registered with a predefined slot. |
| // The list of shutdown hooks is as follows: |
| // (0) Console restore hook |
| // (1) ApplicationShutdownHooks that invokes all registered application |
| // shutdown hooks and waits until they finish |
| // (2) DeleteOnExit hook |
| private static final int MAX_SYSTEM_HOOKS = 10; |
| private static final Runnable[] hooks = new Runnable[MAX_SYSTEM_HOOKS]; |
| |
| // the index of the currently running shutdown hook to the hooks array |
| private static int currentRunningHook = -1; |
| |
| /* 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(); |
| |
| /** |
| * Add a new system shutdown hook. Checks the shutdown state and |
| * the hook itself, but does not do any security checks. |
| * |
| * The registerShutdownInProgress parameter should be false except |
| * registering the DeleteOnExitHook since the first file may |
| * be added to the delete on exit list by the application shutdown |
| * hooks. |
| * |
| * @params slot the slot in the shutdown hook array, whose element |
| * will be invoked in order during shutdown |
| * @params registerShutdownInProgress true to allow the hook |
| * to be registered even if the shutdown is in progress. |
| * @params hook the hook to be registered |
| * |
| * @throws IllegalStateException |
| * if registerShutdownInProgress is false and shutdown is in progress; or |
| * if registerShutdownInProgress is true and the shutdown process |
| * already passes the given slot |
| */ |
| static void add(int slot, boolean registerShutdownInProgress, Runnable hook) { |
| if (slot < 0 || slot >= MAX_SYSTEM_HOOKS) { |
| throw new IllegalArgumentException("Invalid slot: " + slot); |
| } |
| synchronized (lock) { |
| if (hooks[slot] != null) |
| throw new InternalError("Shutdown hook at slot " + slot + " already registered"); |
| |
| if (!registerShutdownInProgress) { |
| if (currentRunningHook >= 0) |
| throw new IllegalStateException("Shutdown in progress"); |
| } else { |
| if (VM.isShutdown() || slot <= currentRunningHook) |
| throw new IllegalStateException("Shutdown in progress"); |
| } |
| |
| hooks[slot] = hook; |
| } |
| } |
| |
| /* Run all system shutdown hooks. |
| * |
| * The system shutdown hooks are run in the thread synchronized on |
| * Shutdown.class. Other threads calling Runtime::exit, Runtime::halt |
| * or JNI DestroyJavaVM will block indefinitely. |
| * |
| * ApplicationShutdownHooks is registered as one single hook that starts |
| * all application shutdown hooks and waits until they finish. |
| */ |
| private static void runHooks() { |
| synchronized (lock) { |
| /* Guard against the possibility of a daemon thread invoking exit |
| * after DestroyJavaVM initiates the shutdown sequence |
| */ |
| if (VM.isShutdown()) return; |
| } |
| |
| for (int i=0; i < MAX_SYSTEM_HOOKS; i++) { |
| try { |
| Runnable hook; |
| synchronized (lock) { |
| // acquire the lock to make sure the hook registered during |
| // shutdown is visible here. |
| currentRunningHook = i; |
| hook = hooks[i]; |
| } |
| if (hook != null) hook.run(); |
| } catch (Throwable t) { |
| if (t instanceof ThreadDeath) { |
| ThreadDeath td = (ThreadDeath)t; |
| throw td; |
| } |
| } |
| } |
| |
| // set shutdown state |
| VM.shutdown(); |
| } |
| |
| /* Notify the VM that it's time to halt. */ |
| static native void beforeHalt(); |
| |
| /* 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); |
| |
| /* 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) { |
| synchronized (lock) { |
| if (status != 0 && VM.isShutdown()) { |
| /* Halt immediately on nonzero status */ |
| halt(status); |
| } |
| } |
| synchronized (Shutdown.class) { |
| /* Synchronize on the class object, causing any other thread |
| * that attempts to initiate shutdown to stall indefinitely |
| */ |
| beforeHalt(); |
| runHooks(); |
| 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 (Shutdown.class) { |
| runHooks(); |
| } |
| } |
| |
| } |