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