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/*
* Copyright (c) 2013, 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 8025173
* @summary Verify that replacing the value for an existing key does not
* corrupt active iterators, in particular due to a resize() occurring and
* not updating modCount.
* @run main ReplaceExisting
*/
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
public class ReplaceExisting {
/* Number of entries required to trigger a resize for cap=16, load=0.75*/
private static int ENTRIES = 13;
public static void main(String[] args) {
for (int i = 0; i <= ENTRIES; i++) {
HashMap<Integer,Integer> hm = prepHashMap();
testItr(hm, i);
}
}
/* Prepare a HashMap that will resize on next put() */
private static HashMap<Integer,Integer> prepHashMap() {
HashMap<Integer,Integer> hm = new HashMap<>(16, 0.75f);
// Add items to one more than the resize threshold
for (int i = 0; i < ENTRIES; i++) {
hm.put(i*10, i*10);
}
return hm;
}
/* Iterate hm for elemBeforePut elements, then call put() to replace value
* for existing key. With bug 8025173, this will also cause a resize, but
* not increase the modCount.
* Finish the iteration to check for a corrupt iterator.
*/
private static void testItr(HashMap<Integer,Integer> hm, int elemBeforePut) {
if (elemBeforePut > hm.size()) {
throw new IllegalArgumentException("Error in test: elemBeforePut must be <= HashMap size");
}
// Create a copy of the keys
HashSet<Integer> keys = new HashSet<>(hm.size());
keys.addAll(hm.keySet());
HashSet<Integer> collected = new HashSet<>(hm.size());
// Run itr for elemBeforePut items, collecting returned elems
Iterator<Integer> itr = hm.keySet().iterator();
for (int i = 0; i < elemBeforePut; i++) {
Integer retVal = itr.next();
if (!collected.add(retVal)) {
throw new RuntimeException("Corrupt iterator: key " + retVal + " already encountered");
}
}
// Do put() to replace entry (and resize table when bug present)
if (null == hm.put(0, 100)) {
throw new RuntimeException("Error in test: expected key 0 to be in the HashMap");
}
// Finish itr + collecting returned elems
while(itr.hasNext()) {
Integer retVal = itr.next();
if (!collected.add(retVal)) {
throw new RuntimeException("Corrupt iterator: key " + retVal + " already encountered");
}
}
// Compare returned elems to original copy of keys
if (!keys.equals(collected)) {
throw new RuntimeException("Collected keys do not match original set of keys");
}
}
}
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