102 lines
3.0 KiB
Java
102 lines
3.0 KiB
Java
/*
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* Copyright (c) 2002, 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 4687909
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* @summary Check Inet6Address.hashCode returns a reasonable spread of hash
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* codes.
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* @key randomness
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*/
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import java.net.InetAddress;
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import java.net.UnknownHostException;
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import java.util.Random;
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public class HashSpread {
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static Random r = new Random();
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/**
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* Generate and return a random IPv6 address.
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*/
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static InetAddress randomIPv6Adress() {
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StringBuffer sb = new StringBuffer();
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for (int i=0; i<8; i++) {
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if (i > 0)
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sb.append(":");
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for (int j=0; j<4; j++) {
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int v = r.nextInt(16);
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if (v < 10) {
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sb.append(Integer.toString(v));
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} else {
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char c = (char) ('A' + v - 10);
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sb.append(c);
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}
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}
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}
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try {
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return InetAddress.getByName(sb.toString());
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} catch (UnknownHostException x) {
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throw new Error("Internal error in test");
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}
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}
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public static void main(String args[]) throws Exception {
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int iterations = 10000;
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if (args.length > 0) {
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iterations = Integer.parseInt(args[0]);
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}
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int MIN_SHORT = (int)Short.MIN_VALUE;
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int MAX_SHORT = (int)Short.MAX_VALUE;
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/*
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* Iterate through 10k hash codes and count the number
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* in the MIN_SHORT-MAX_SHORT range.
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*/
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int narrow = 0;
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for (int i=0; i<iterations; i++) {
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int hc = randomIPv6Adress().hashCode();
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if (hc >= MIN_SHORT && hc <= MAX_SHORT) {
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narrow++;
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}
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}
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/*
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* If >85% of hash codes in the range then fail.
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*/
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double percent = (double)narrow / (double)iterations * 100.0;
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if (percent > 85.0) {
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throw new RuntimeException(percent + " of hash codes were in " +
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MIN_SHORT + " to " + MAX_SHORT + " range.");
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}
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}
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}
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