| /* |
| * Copyright (c) 2015, 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 |
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| */ |
| |
| /** |
| * @test |
| * @bug 8071507 |
| * @summary Test that PhantomReferences are cleared when notified. |
| * @run main/othervm PhantomReferentClearing |
| */ |
| |
| import java.lang.ref.PhantomReference; |
| import java.lang.ref.ReferenceQueue; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| public class PhantomReferentClearing { |
| |
| private static final long ENQUEUE_TIMEOUT = 1000; // 1 sec, in millis |
| |
| // P1 & P2 are PhantomReference objects |
| // O1 & O2 are objects |
| // |
| // -> is a strong reference |
| // => is a referent reference |
| // |
| // root -> P1 |
| // root -> P2 |
| // root -> O1 |
| // root -> O2 |
| // O1 -> O2 |
| // P1 => O1 |
| // P2 => O2 |
| // |
| // (1) Remove root -> O1 and collect. P1 notified, P2 !notified. |
| // (2) Remove root -> O2 and collect. |
| // |
| // If phantom references are cleared when notified, as proposed by |
| // 8071507, then P2 should be notified, and the test passes. |
| // |
| // Otherwise, P2 does not get notified because it remains reachable |
| // from O1, which is being retained by P1. This fails the test. |
| |
| private static final ReferenceQueue<Object> Q1 = new ReferenceQueue<>(); |
| private static final ReferenceQueue<Object> Q2 = new ReferenceQueue<>(); |
| |
| private static volatile Object O2 = new Object(); |
| private static volatile List<Object> O1 = new ArrayList<>(); |
| static { |
| O1.add(O2); |
| } |
| |
| private static final PhantomReference<Object> P1 = new PhantomReference<>(O1, Q1); |
| private static final PhantomReference<Object> P2 = new PhantomReference<>(O2, Q2); |
| |
| public static void main(String[] args) throws InterruptedException { |
| |
| // Collect, and verify neither P1 or P2 notified. |
| System.gc(); |
| if (Q1.remove(ENQUEUE_TIMEOUT) != null) { |
| throw new RuntimeException("P1 already notified"); |
| } else if (Q2.poll() != null) { |
| throw new RuntimeException("P2 already notified"); |
| } |
| |
| // Delete root -> O1, collect, verify P1 notified, P2 not notified. |
| O1 = null; |
| System.gc(); |
| if (Q1.remove(ENQUEUE_TIMEOUT) == null) { |
| throw new RuntimeException("P1 not notified by O1 deletion"); |
| } else if (Q2.remove(ENQUEUE_TIMEOUT) != null) { |
| throw new RuntimeException("P2 notified by O1 deletion."); |
| } |
| |
| // Delete root -> O2, collect. P2 should be notified. |
| O2 = null; |
| System.gc(); |
| if (Q2.remove(ENQUEUE_TIMEOUT) == null) { |
| throw new RuntimeException("P2 not notified by O2 deletion"); |
| } |
| } |
| } |