--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/net/InetAddress/HashSpread.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2002 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.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.");
+ }
+
+ }
+
+}