RFR : 8182672: Java 8u121 on Linux intermittently returns null for MAC address

[Chris Hegarty]

On 23/06/17 10:56, Seán Coffey wrote:
> Thanks to Christoph, Vyom and Mark for the reviews.
>
> I've improved the testcase as per feedback. Hope this meets all requests :
>
> http://cr.openjdk.java.net/~coffeys/webrev.8182672.jdk10.v2/webrev/

The change looks good.

Sean and I did a live coding session and arrived at the following
version of the test.

-Chris.

/*
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  * 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.
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/*
  * @test
  * @bug 8182672
  * @summary Java 8u121 on Linux intermittently returns null for MAC address
  */

import java.net.NetworkInterface;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.Phaser;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class GetMacAddress implements Callable<Exception> {
     static final int NUM_THREADS = 5;
     static final int NUM_ITERS = 100;
     static volatile boolean failed; // false

     final String threadName;
     final NetworkInterface ni;
     final Phaser startingGate;

     public GetMacAddress(NetworkInterface ni, String name, Phaser phaser) {
         this.ni = ni;
         this.threadName = name;
         this.startingGate = phaser;
     }

     @Override
     public Exception call() {
         int count = 0;
         startingGate.arriveAndAwaitAdvance();
         try {
             for (int i = 0; i < NUM_ITERS; i++) {
                 ni.getMTU();
                 byte[] addr = ni.getHardwareAddress();
                 if (addr == null) {
                     System.out.println(threadName + ". mac id is null");
                     failed = true;
                 }
                 count = count + 1;
                 if (count % 100 == 0) {
                     System.out.println(threadName + ". count is " + count);
                 }
             }
         } catch (Exception ex) {
             System.out.println(threadName + ". Not expecting 
exception:" + ex.getMessage());
             failed = true;
             return ex;
         }
         return null;
     }

     static final Predicate<NetworkInterface> hasHardwareAddress = ni -> {
         try {
             if (ni.getHardwareAddress() == null) {
                 System.out.println("Not testing null addr: " + 
ni.getName());
                 return false;
             }
         } catch (Exception ex) {
             System.out.println("Not testing: " + ni.getName() +
                     " " + ex.getMessage());
         }
         return true;
     };

     public static void main(String[] args) throws Exception {
         List<NetworkInterface> toTest = 
NetworkInterface.networkInterfaces()
                         .filter(hasHardwareAddress)
                         .collect(Collectors.toList());

         ExecutorService executor = 
Executors.newFixedThreadPool(NUM_THREADS);

         for (NetworkInterface ni : toTest) {
             Phaser startingGate = new Phaser(NUM_THREADS);
             System.out.println("Testing: " + ni.getName());
             List<Callable<Exception>> list = new ArrayList<>();
             for (int i = 0; i < NUM_THREADS; i++)
                 list.add(new GetMacAddress(ni, ni.getName() + 
"-Thread-" + i, startingGate));
             List<Future<Exception>> futures = executor.invokeAll(list);
             for (Future<Exception> f : futures) {
                 if (f.get() != null)
                     f.get().printStackTrace(System.out);
             }
             if (failed)
                 break;
         }
         executor.shutdownNow();
         if (!failed) {
             System.out.println("PASSED - Finished all threads");
         } else {
             throw new RuntimeException("Failed");
         }
     }
}