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