cassandra-trunk/test/long/org/apache/cassandra/locator/DynamicEndpointSnitchLongTest.java
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package org.apache.cassandra.locator;

import java.io.IOException;
import java.util.*;

import org.junit.Test;

import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.service.StorageService;

import org.apache.cassandra.utils.FBUtilities;

import static java.util.concurrent.TimeUnit.MILLISECONDS;

public class DynamicEndpointSnitchLongTest
{
    static
    {
        DatabaseDescriptor.daemonInitialization();
    }

    @Test
    public void testConcurrency() throws InterruptedException, IOException, ConfigurationException
    {
        // The goal of this test is to check for CASSANDRA-8448/CASSANDRA-9519
        double badness = DatabaseDescriptor.getDynamicBadnessThreshold();
        DatabaseDescriptor.setDynamicBadnessThreshold(0.0);

        try
        {
            final int ITERATIONS = 10000;

            // do this because SS needs to be initialized before DES can work properly.
            StorageService.instance.unsafeInitialize();
            SimpleSnitch ss = new SimpleSnitch();
            DynamicEndpointSnitch dsnitch = new DynamicEndpointSnitch(ss, String.valueOf(ss.hashCode()));
            InetAddressAndPort self = FBUtilities.getBroadcastAddressAndPort();

            EndpointsForRange.Builder replicasBuilder = EndpointsForRange.builder(ReplicaUtils.FULL_RANGE);
            // We want a big list of hosts so  sorting takes time, making it much more likely to reproduce the
            // problem we're looking for.
            for (int i = 0; i < 100; i++)
                for (int j = 0; j < 256; j++)
                    replicasBuilder.add(ReplicaUtils.full(InetAddressAndPort.getByAddress(new byte[]{ 127, 0, (byte)i, (byte)j})));

            EndpointsForRange replicas = replicasBuilder.build();

            ScoreUpdater updater = new ScoreUpdater(dsnitch, replicas);
            updater.start();

            EndpointsForRange result = replicas;
            for (int i = 0; i < ITERATIONS; i++)
                result = dsnitch.sortedByProximity(self, result);

            updater.stopped = true;
            updater.join();
        }
        finally
        {
            DatabaseDescriptor.setDynamicBadnessThreshold(badness);
        }
    }

    public static class ScoreUpdater extends Thread
    {
        private static final int SCORE_RANGE = 100;

        public volatile boolean stopped;

        private final DynamicEndpointSnitch dsnitch;
        private final EndpointsForRange hosts;
        private final Random random = new Random();

        public ScoreUpdater(DynamicEndpointSnitch dsnitch, EndpointsForRange hosts)
        {
            this.dsnitch = dsnitch;
            this.hosts = hosts;
        }

        public void run()
        {
            while (!stopped)
            {
                Replica host = hosts.get(random.nextInt(hosts.size()));
                int score = random.nextInt(SCORE_RANGE);
                dsnitch.receiveTiming(host.endpoint(), score, MILLISECONDS);
            }
        }
    }
}

