LowestShardCountDistributionPolicyTest.java

/**
 * Copyright 2008 the original author or authors.
 *
 * Licensed 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 net.sf.katta.master;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import net.sf.katta.AbstractTest;

import org.junit.Test;

public class LowestShardCountDistributionPolicyTest extends AbstractTest {

  private LowestShardCountDistributionPolicy _distributionPolicy = new LowestShardCountDistributionPolicy();
  Map<String, List<String>> _currentShard2NodesMap = new HashMap<String, List<String>>();
  Map<String, List<String>> _currentNode2ShardsMap = new HashMap<String, List<String>>();

  @Test
  public void testInitialDistribution() throws Exception {
    int replicationLevel = 2;
    List<String> nodes = createNodes("node1", "node2", "node3");
    Set<String> shards = createShards("shard1", "shard2");
    Map<String, List<String>> node2ShardsMap = _distributionPolicy.createDistributionPlan(_currentShard2NodesMap,
            _currentNode2ShardsMap, nodes, replicationLevel);
    assertEquals(nodes.size(), node2ShardsMap.size());
    assertSufficientDistribution(replicationLevel, nodes, shards, node2ShardsMap);
  }

  @Test
  public void testInitialDistribution_TooLessNodes() throws Exception {
    List<String> nodes = createNodes("node1");
    Set<String> shards = createShards("shard1", "shard2");
    Map<String, List<String>> node2ShardsMap = _distributionPolicy.createDistributionPlan(_currentShard2NodesMap,
            _currentNode2ShardsMap, nodes, 3);
    assertEquals(nodes.size(), node2ShardsMap.size());
    assertEquals(shards.size(), node2ShardsMap.get("node1").size());
  }

  @Test
  public void testUnderReplicatedDistribution() throws Exception {
    int replicationLevel = 3;
    List<String> nodes = createNodes("node1", "node2", "node3");
    Set<String> shards = createShards("shard1", "shard2", "shard3");
    addMapping("shard1", "node1", "node2", "node3");
    addMapping("shard2", "node1");

    Map<String, List<String>> node2ShardsMap = _distributionPolicy.createDistributionPlan(_currentShard2NodesMap,
            _currentNode2ShardsMap, nodes, replicationLevel);
    assertEquals(nodes.size(), node2ShardsMap.size());
    assertSufficientDistribution(replicationLevel, nodes, shards, node2ShardsMap);
  }

  @Test
  public void testOverReplicatedDistribution() throws Exception {
    int replicationLevel = 2;
    List<String> nodes = createNodes("node1", "node2", "node3", "node4");
    Set<String> shards = createShards("shard1", "shard2");
    addMapping("shard1", "node1", "node2", "node3", "node4");
    addMapping("shard2", "node1", "node2");

    Map<String, List<String>> node2ShardsMap = _distributionPolicy.createDistributionPlan(_currentShard2NodesMap,
            _currentNode2ShardsMap, nodes, replicationLevel);
    assertEquals(nodes.size(), node2ShardsMap.size());
    assertSufficientDistribution(replicationLevel, nodes, shards, node2ShardsMap);
  }

  private void assertSufficientDistribution(int replicationLevel, List<String> nodes, Set<String> shards,
          Map<String, List<String>> node2ShardsMap) {
    int deployedShardCount = 0;
    for (String node : nodes) {
      deployedShardCount += node2ShardsMap.get(node).size();
      if (deployedShardCount == 0) {
        continue;
      }
      assertTrue(node2ShardsMap.get(node).size() >= 1);
      assertTrue(node2ShardsMap.get(node).size() <= replicationLevel);
    }
    assertEquals(shards.size() * replicationLevel, deployedShardCount);
  }

  private void addMapping(String shard, String... nodes) {
    List<String> shardNodes = _currentShard2NodesMap.get(shard);
    for (String node : nodes) {
      List<String> shards = _currentNode2ShardsMap.get(node);
      shards.add(shard);
      shardNodes.add(node);
    }
  }

  private List<String> createNodes(String... nodeNames) {
    List<String> nodes = new ArrayList<String>();
    for (String nodeName : nodeNames) {
      nodes.add(nodeName);
      _currentNode2ShardsMap.put(nodeName, new ArrayList<String>());
    }
    return nodes;
  }

  private Set<String> createShards(String... shardNames) {
    Set<String> shards = new HashSet<String>();
    for (String shardName : shardNames) {
      shards.add(shardName);
      _currentShard2NodesMap.put(shardName, new ArrayList<String>());
    }
    return shards;
  }
}