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/*
* 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.
* @key randomness
*/
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.");
}
}
}
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