/*

 * Copyright (c) 2002, 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 4687909

 * @summary Check Inet6Address.hashCode returns a reasonable spread of hash

 *          codes.

 */

import java.net.InetAddress;

import java.net.UnknownHostException;

import java.util.Random;

public class HashSpread {

    static Random r = new Random();

    /**

     * Generate and return a random IPv6 address.

     */

    static InetAddress randomIPv6Adress() {

        StringBuffer sb = new StringBuffer();

        for (int i=0; i<8; i++) {

            if (i > 0)

                sb.append(":");

            for (int j=0; j<4; j++) {

                int v = r.nextInt(16);

                if (v < 10) {

                    sb.append(Integer.toString(v));

                } else {

                    char c = (char) ('A' + v - 10);

                    sb.append(c);

                }

            }

        }

        try {

            return InetAddress.getByName(sb.toString());

        } catch (UnknownHostException x) {

            throw new Error("Internal error in test");

        }

    }

    public static void main(String args[]) throws Exception {

        int iterations = 10000;

        if (args.length > 0) {

            iterations = Integer.parseInt(args[0]);

        }

        int MIN_SHORT = (int)Short.MIN_VALUE;

        int MAX_SHORT = (int)Short.MAX_VALUE;

        /*

         * Iterate through 10k hash codes and count the number

         * in the MIN_SHORT-MAX_SHORT range.

         */

        int narrow = 0;

        for (int i=0; i<iterations; i++) {

            int hc = randomIPv6Adress().hashCode();

            if (hc >= MIN_SHORT && hc <= MAX_SHORT) {

                narrow++;

            }

        }

        /*

         * If >85% of hash codes in the range then fail.

         */

        double percent = (double)narrow / (double)iterations * 100.0;

        if (percent > 85.0) {

            throw new RuntimeException(percent + " of hash codes were in " +

                MIN_SHORT + " to " + MAX_SHORT  + " range.");

        }

    }

}