heron/simulator/tests/java/org/apache/heron/simulator/grouping/ShuffleGroupingTest.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.heron.simulator.grouping;

import java.util.LinkedList;
import java.util.List;

import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import org.apache.heron.proto.system.HeronTuples;

public class ShuffleGroupingTest {

  @Before
  public void before() throws Exception {
  }

  @After
  public void after() throws Exception {
  }

  /**
   * Method: test round robin nature of shuffle grouping
   */
  @Test
  public void testRoundRobin() throws Exception {
    List<Integer> taskIds = new LinkedList<>();
    taskIds.add(0);
    taskIds.add(2);
    taskIds.add(4);
    taskIds.add(8);

    ShuffleGrouping g = new ShuffleGrouping(taskIds);
    HeronTuples.HeronDataTuple dummy = HeronTuples.HeronDataTuple.getDefaultInstance();
    List<Integer> dest = g.getListToSend(dummy);

    Assert.assertEquals(dest.size(), 1);
    int first = dest.get(0);
    int index = -1;
    for (int i = 0; i < taskIds.size(); ++i) {
      if (taskIds.get(i) == first) {
        index = i;
        break;
      }
    }
    dest.clear();

    for (int i = 0; i < 100; ++i) {
      dest = g.getListToSend(dummy);

      Assert.assertEquals(dest.size(), 1);
      int d = dest.get(0);
      index = (index + 1) % taskIds.size();
      Assert.assertEquals((Integer) d, taskIds.get(index));
      dest.clear();
    }
  }

  /**
   * Method: test random start
   */
  @Test
  public void testRandomStart() throws Exception {
    List<Integer> taskIds = new LinkedList<>();
    taskIds.add(0);
    taskIds.add(1);

    int zeros = 0;
    int ones = 0;
    int count = 1000;

    for (int i = 0; i < count; ++i) {
      ShuffleGrouping g = new ShuffleGrouping(taskIds);
      HeronTuples.HeronDataTuple dummy = HeronTuples.HeronDataTuple.getDefaultInstance();
      List<Integer> dest = g.getListToSend(dummy);

      Assert.assertEquals(dest.size(), 1);
      int first = dest.get(0);
      if (first == 0) {
        zeros++;
      } else {
        ones++;
      }
      dest.clear();
    }

    double variance = ((double) Math.abs(zeros - ones)) / count;
    Assert.assertTrue(variance <= 0.1);
  }
}