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Diffstat (limited to 'test/sun/security/ssl/SessionIdCollisionTest.java')
| -rw-r--r-- | test/sun/security/ssl/SessionIdCollisionTest.java | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/test/sun/security/ssl/SessionIdCollisionTest.java b/test/sun/security/ssl/SessionIdCollisionTest.java new file mode 100644 index 0000000000..16582f4e07 --- /dev/null +++ b/test/sun/security/ssl/SessionIdCollisionTest.java @@ -0,0 +1,158 @@ +/* + * Copyright (c) 2019, Red Hat 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ +import java.lang.reflect.Constructor; +import java.security.SecureRandom; +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + + +/** + * @test + * @bug 8203190 + * @summary Manual test to verify number of collisions in + * sun.security.ssl.SessionId.hashCode() + * @run main/manual SessionIdCollisionTest 100 20480 10000000 + */ + +/** + * + * Notes: + * - This is a manual test, not run automatically. + * - New default value of javax.net.ssl.sessionCacheSize in JDK 12+ is 20480 + * - According to JDK-8210985 24 hours expired cache may exceed several million + * entries = > 10_000_000 + * + * Example usage: java SessionIdCollissionTest 100 20480 10000000 + * + * Expected outcome of running the test is to see fewer collisions and, more + * importantly fewer elements in buckets when there are collisions. See: + * http://mail.openjdk.java.net/pipermail/jdk8u-dev/2019-May/009345.html + * + */ +public class SessionIdCollisionTest { + + private List<Integer> prepareHashCodes(int total) throws Exception { + Class<?> sessionIdClass = Class.forName("sun.security.ssl.SessionId"); + Constructor<?> c = sessionIdClass.getDeclaredConstructor(byte[].class); + c.setAccessible(true); + // case of rejoinable session ids generates 32 random bytes + byte[] sessionIdBytes = new byte[32]; + List<Integer> hashCodes = new ArrayList<>(); + for (int i = 0; i < total; i++) { + SecureRandom random = new SecureRandom(); + random.nextBytes(sessionIdBytes); + Object sessionId = c.newInstance(sessionIdBytes); + int hashCode = sessionId.hashCode(); + hashCodes.add(hashCode); + } + return hashCodes; + } + + private void printSummary(boolean withDistribution, + List<Integer> hashCodes) throws Exception { + final int bound = hashCodes.size(); + Collections.sort(hashCodes); + int collisions = 0; + Map<Integer, List<Integer>> collCountsReverse = new HashMap<>(); + for (int i = 0; i < bound - 1; i++) { + int oldval = hashCodes.get(i); + int nextval = hashCodes.get(i+1); + if (oldval == nextval) { + collisions++; + if (i == bound - 2) { // last elements + updateCollCountsReverse(collisions, collCountsReverse, oldval); + } + } else { + updateCollCountsReverse(collisions, collCountsReverse, oldval); + collisions = 0; + if (i == bound - 2) { // last elements + updateCollCountsReverse(collisions, collCountsReverse, nextval); + } + } + } + if (withDistribution) { + System.out.println("---- distribution ----"); + } + int collCount = 0; + int maxLength = 0; + List<Integer> sorted = new ArrayList<>(collCountsReverse.size()); + sorted.addAll(collCountsReverse.keySet()); + Collections.sort(sorted); + for (Integer coll: sorted) { + List<Integer> hc = collCountsReverse.get(coll); + if (withDistribution) { + System.out.printf("Hashcodes with %02d collisions | " + + "hashCodes: %s\n", coll, hc.toString()); + } + collCount += coll * hc.size(); + if (coll > maxLength) { + maxLength = coll; + } + } + if (withDistribution) { + System.out.println("---- distribution ----"); + } + System.out.println("Total number of collisions: " + collCount); + if (collCount > 0) { + System.out.println("Max length of collision list over all buckets: " + + maxLength); + } + } + + private void updateCollCountsReverse(int collisions, + Map<Integer, List<Integer>> reverse, int val) { + List<Integer> hc = reverse.get(collisions); + if (hc == null) { + hc = new ArrayList<>(); + hc.add(val); + reverse.put(collisions, hc); + } else { + hc.add(val); + } + } + + public void doCollissionTest(int total) throws Exception { + System.out.println("Collision test for " + total + " sessions:"); + System.out.println("------------------------------------------------"); + List<Integer> hashcodes = prepareHashCodes(total); + printSummary(false, hashcodes); + System.out.println(); + } + + public static void main(String[] args) throws Exception { + if (args.length < 1) { + System.err.println("java " + SessionIdCollisionTest.class.getSimpleName() + + "<num-sessions> [<num-sessions> ...]"); + System.exit(1); + } + SessionIdCollisionTest collTest = new SessionIdCollisionTest(); + for (int i = 0; i < args.length; i++) { + int total = Integer.parseInt(args[i]); + collTest.doCollissionTest(total); + } + } + +} |