134 lines
4.2 KiB
Java
134 lines
4.2 KiB
Java
/*
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* Copyright (c) 2001, 2018, 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.
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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 nsk.share;
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import java.util.Stack;
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/**
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* Finalizer performs object finalization when virtual mashine shuts down.
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* Finalizer is a thread that acts as a VM shutdown hook.
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* This thread will be activated as VM shuts down because of
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* invocation of <code>exit()</code> or termination. After activation
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* Finalizer just calls <code>finalizeAtExit()</code> method of the specified object.
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* The finalizable object should implement interface <code>Finalizable</code>.
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*
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* @see Finalizable
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*/
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public class Finalizer {
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/** Finalizer thread to register as a VM shutdown hook. */
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private static FinalizerThread finalizerThread = null;
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/** An object to finalize. */
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private Finalizable object;
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/**
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* Create finalizer for the specified object.
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*/
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public Finalizer(Finalizable object) {
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this.object = object;
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}
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/**
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* Register finalizer for finalization at VM shutdown.
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*/
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public void activate() {
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if (finalizerThread == null) {
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finalizerThread = new FinalizerThread("FinalizerThread for Finalizable objects");
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finalizerThread.activate();
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}
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finalizerThread.add(object);
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}
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/**
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* Unregister finalizer for finalization at VM shutdown.
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*/
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public void deactivate() {
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if (finalizerThread == null)
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return;
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finalizerThread.remove(object);
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}
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/**
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* Static inner thread that is registered as a VM shutdown hook
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* and performs finalization of all registered finalizable objects.
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*/
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private static class FinalizerThread extends Thread {
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/** Stack of objects registered for finalization. */
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private Stack<Object> objects = new Stack<Object>();
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/** Make new instance of FinalizerThread with given thread name. */
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public FinalizerThread(String threadName) {
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super(threadName);
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}
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/**
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* Push an object to the stack of registered objects.
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*/
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public void add(Finalizable object) {
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objects.push(object);
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}
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/**
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* Remove an object from the stack of registered objects.
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*/
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public void remove(Finalizable object) {
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objects.remove(object);
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}
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/**
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* Register finalizer thread as a VM shutdown hook.
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*/
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public void activate() {
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Runtime.getRuntime().addShutdownHook( this );
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}
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/**
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* Unregister finalizer thread as a VM shutdown hook.
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*/
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public void deactivate() {
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Runtime.getRuntime().removeShutdownHook( this );
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}
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/**
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* Pop all registered objects from the stack and finalize them.
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*/
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public void run() {
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while (!objects.empty()) {
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Finalizable object = (Finalizable)objects.pop();
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try {
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object.finalizeAtExit();
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} catch (ThreadDeath e) {
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throw e;
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} catch (Throwable ex) {
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ex.printStackTrace();
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}
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}
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}
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} // end of FinalizerThread
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} // end of Finalizer
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