| /* |
| * 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"); |
| } |
| } |
| } |