90 lines
3.0 KiB
Java
90 lines
3.0 KiB
Java
/*
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* Copyright (c) 1999, 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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/* @test
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* @bug 4178693
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* @summary Ensure that null queue arguments don't crash the Reference handler
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* @author Mark Reinhold
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*/
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import java.lang.ref.Reference;
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import java.lang.ref.WeakReference;
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public class NullQueue {
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private static Reference r = null;
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private static Thread findThread(String name) {
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/* Find reference-handler thread */
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ThreadGroup tg = Thread.currentThread().getThreadGroup();
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for (ThreadGroup tgn = tg;
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tgn != null;
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tg = tgn, tgn = tg.getParent());
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int nt = tg.activeCount();
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Thread[] ts = new Thread[nt];
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tg.enumerate(ts);
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Thread refHandler = null;
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for (int i = 0; i < ts.length; i++) {
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if (ts[i].getName().equals(name)) return ts[i];
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}
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return null;
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}
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private static void fork(Runnable proc) throws InterruptedException {
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Thread t = new Thread(proc);
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t.start();
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t.join();
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}
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public static void main(String[] args) throws Exception {
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Thread refHandler = findThread("Reference Handler");
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if (refHandler == null)
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throw new Exception("Couldn't find Reference-handler thread");
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if (!refHandler.isAlive())
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throw new Exception("Reference-handler thread is not alive");
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/* Invoke a Reference constructor, passing null for the queue */
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fork(new Runnable() {
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public void run() {
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r = new WeakReference(new Object(), null);
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}});
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/* Force the reference to be cleared and enqueued by the GC */
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for (int i = 0;; i++) {
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Thread.sleep(10);
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System.gc();
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if (r.get() == null) break;
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if (i >= 10)
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throw new Exception("Couldn't cause weak ref to be cleared");
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}
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/* Check that the handler is still alive */
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if (!refHandler.isAlive())
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throw new Exception("Reference-handler thread died");
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}
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}
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