267 lines
9.7 KiB
Java
267 lines
9.7 KiB
Java
/*
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* Copyright (c) 2007, 2017, 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 6499848
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* @library /test/lib
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* @build jdk.test.lib.RandomFactory
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* @run main GCDuringIteration
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* @summary Check that iterators work properly in the presence of
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* concurrent finalization and removal of elements.
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* @key randomness
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*/
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import jdk.test.lib.RandomFactory;
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import java.lang.ref.ReferenceQueue;
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import java.lang.ref.WeakReference;
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import java.util.Arrays;
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import java.util.Iterator;
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import java.util.Map;
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import java.util.NoSuchElementException;
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import java.util.Random;
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import java.util.WeakHashMap;
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import java.util.concurrent.CountDownLatch;
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import java.util.function.BooleanSupplier;
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import static java.util.concurrent.TimeUnit.MILLISECONDS;
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public class GCDuringIteration {
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/** No guarantees, but effective in practice. */
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static void forceFullGc() {
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long timeoutMillis = 1000L;
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CountDownLatch finalized = new CountDownLatch(1);
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ReferenceQueue<Object> queue = new ReferenceQueue<>();
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WeakReference<Object> ref = new WeakReference<>(
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new Object() { protected void finalize() { finalized.countDown(); }},
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queue);
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try {
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for (int tries = 3; tries--> 0; ) {
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System.gc();
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if (finalized.await(timeoutMillis, MILLISECONDS)
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&& queue.remove(timeoutMillis) != null
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&& ref.get() == null) {
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System.runFinalization(); // try to pick up stragglers
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return;
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}
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timeoutMillis *= 4;
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}
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} catch (InterruptedException unexpected) {
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throw new AssertionError("unexpected InterruptedException");
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}
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throw new AssertionError("failed to do a \"full\" gc");
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}
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static void gcAwait(BooleanSupplier s) {
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for (int i = 0; i < 10; i++) {
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if (s.getAsBoolean())
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return;
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forceFullGc();
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}
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throw new AssertionError("failed to satisfy condition");
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}
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// A class with the traditional pessimal hashCode implementation,
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// to ensure that all instances end up in the same bucket.
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static class Foo { public int hashCode() { return 42; }}
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<K,V> void put(Map<K,V> map, K k, V v) {
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check(! map.containsKey(k));
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equal(map.get(k), null);
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equal(map.put(k, v), null);
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equal(map.get(k), v);
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check(map.containsKey(k));
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equal(map.put(k, v), v);
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equal(map.get(k), v);
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check(map.containsKey(k));
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check(! map.isEmpty());
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equal(map.keySet().iterator().next(), k);
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equal(map.values().iterator().next(), v);
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}
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static final Random rnd = RandomFactory.getRandom();
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void checkIterator(final Iterator<Map.Entry<Foo, Integer>> it, int first) {
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for (int i = first; i >= 0; --i) {
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if (rnd.nextBoolean()) check(it.hasNext());
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equal(it.next().getValue(), i);
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}
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if (rnd.nextBoolean()) {
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try {
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it.next();
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throw new AssertionError("should throw");
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} catch (NoSuchElementException success) {}
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}
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if (rnd.nextBoolean())
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check(! it.hasNext());
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}
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<K,V> V firstValue(Map<K,V> map) {
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return map.values().iterator().next();
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}
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void test(String[] args) throws Throwable {
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final int n = 10;
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// Create array of strong refs
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final Foo[] foos = new Foo[2*n];
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final Map<Foo,Integer> map = new WeakHashMap<>(foos.length);
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check(map.isEmpty());
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equal(map.size(), 0);
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for (int i = 0; i < foos.length; i++) {
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Foo foo = new Foo();
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foos[i] = foo;
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put(map, foo, i);
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}
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equal(map.size(), foos.length);
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{
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int first = firstValue(map);
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final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
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foos[first] = null;
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gcAwait(() -> map.size() == first);
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checkIterator(it, first-1);
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equal(map.size(), first);
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equal(firstValue(map), first-1);
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}
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{
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int first = firstValue(map);
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final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
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it.next(); // protects first entry
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System.out.println(map.values());
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int oldSize = map.size();
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foos[first] = null;
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forceFullGc();
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equal(map.size(), oldSize);
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System.out.println(map.values());
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checkIterator(it, first-1);
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// first entry no longer protected
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gcAwait(() -> map.size() == first);
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equal(firstValue(map), first-1);
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}
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{
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int first = firstValue(map);
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final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
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it.next(); // protects first entry
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System.out.println(map.values());
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foos[first] = foos[first-1] = null;
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gcAwait(() -> map.size() == first);
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equal(firstValue(map), first);
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System.out.println(map.values());
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checkIterator(it, first-2);
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// first entry no longer protected
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gcAwait(() -> map.size() == first-1);
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equal(firstValue(map), first-2);
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}
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{
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int first = firstValue(map);
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final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
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it.next(); // protects first entry
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it.hasNext(); // protects second entry
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System.out.println(map.values());
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int oldSize = map.size();
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foos[first] = foos[first-1] = null;
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forceFullGc();
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equal(map.size(), oldSize);
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equal(firstValue(map), first);
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System.out.println(map.values());
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checkIterator(it, first-1);
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// first entry no longer protected
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gcAwait(() -> map.size() == first-1);
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equal(firstValue(map), first-2);
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}
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{
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int first = firstValue(map);
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final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
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it.next(); // protects first entry
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System.out.println(map.values());
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equal(map.size(), first+1);
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foos[first] = foos[first-1] = null;
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gcAwait(() -> map.size() == first);
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it.remove();
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equal(firstValue(map), first-2);
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equal(map.size(), first-1);
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System.out.println(map.values());
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checkIterator(it, first-2);
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// first entry no longer protected
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gcAwait(() -> map.size() == first-1);
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equal(firstValue(map), first-2);
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}
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{
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int first = firstValue(map);
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final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
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it.next(); // protects first entry
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it.remove();
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it.hasNext(); // protects second entry
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System.out.println(map.values());
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equal(map.size(), first);
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foos[first] = foos[first-1] = null;
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forceFullGc();
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equal(firstValue(map), first-1);
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equal(map.size(), first);
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System.out.println(map.values());
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checkIterator(it, first-1);
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gcAwait(() -> map.size() == first-1);
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equal(firstValue(map), first-2);
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}
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{
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int first = firstValue(map);
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final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
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it.hasNext(); // protects first entry
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Arrays.fill(foos, null);
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gcAwait(() -> map.size() == 1);
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System.out.println(map.values());
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equal(it.next().getValue(), first);
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check(! it.hasNext());
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gcAwait(() -> map.size() == 0);
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check(map.isEmpty());
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}
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}
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//--------------------- Infrastructure ---------------------------
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volatile int passed = 0, failed = 0;
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void pass() {passed++;}
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void fail() {failed++; Thread.dumpStack();}
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void fail(String msg) {System.err.println(msg); fail();}
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void unexpected(Throwable t) {failed++; t.printStackTrace();}
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void check(boolean cond) {if (cond) pass(); else fail();}
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void equal(Object x, Object y) {
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if (x == null ? y == null : x.equals(y)) pass();
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else fail(x + " not equal to " + y);}
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public static void main(String[] args) throws Throwable {
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new GCDuringIteration().instanceMain(args);}
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void instanceMain(String[] args) throws Throwable {
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try {test(args);} catch (Throwable t) {unexpected(t);}
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System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
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if (failed > 0) throw new AssertionError("Some tests failed");}
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}
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