/*

 * 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

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 * 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");

        }

    }

}