/**
* 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.hadoop.net;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.commons.math3.stat.inference.ChiSquareTest;
import org.junit.Assert;
import org.junit.Test;
public class TestClusterTopology extends Assert {
public static class NodeElement implements Node {
private String location;
private String name;
private Node parent;
private int level;
public NodeElement(String name) {
this.name = name;
}
@Override
public String getNetworkLocation() {
return location;
}
@Override
public void setNetworkLocation(String location) {
this.location = location;
}
@Override
public String getName() {
return name;
}
@Override
public Node getParent() {
return parent;
}
@Override
public void setParent(Node parent) {
this.parent = parent;
}
@Override
public int getLevel() {
return level;
}
@Override
public void setLevel(int i) {
this.level = i;
}
}
/**
* Test the count of nodes with exclude list
*/
@Test
public void testCountNumNodes() throws Exception {
// create the topology
NetworkTopology cluster = new NetworkTopology();
NodeElement node1 = getNewNode("node1", "/d1/r1");
cluster.add(node1);
NodeElement node2 = getNewNode("node2", "/d1/r2");
cluster.add(node2);
NodeElement node3 = getNewNode("node3", "/d1/r3");
cluster.add(node3);
NodeElement node4 = getNewNode("node4", "/d1/r4");
cluster.add(node4);
// create exclude list
List<Node> excludedNodes = new ArrayList<Node>();
assertEquals("4 nodes should be available", 4,
cluster.countNumOfAvailableNodes(NodeBase.ROOT, excludedNodes));
NodeElement deadNode = getNewNode("node5", "/d1/r2");
excludedNodes.add(deadNode);
assertEquals("4 nodes should be available with extra excluded Node", 4,
cluster.countNumOfAvailableNodes(NodeBase.ROOT, excludedNodes));
// add one existing node to exclude list
excludedNodes.add(node4);
assertEquals("excluded nodes with ROOT scope should be considered", 3,
cluster.countNumOfAvailableNodes(NodeBase.ROOT, excludedNodes));
assertEquals("excluded nodes without ~ scope should be considered", 2,
cluster.countNumOfAvailableNodes("~" + deadNode.getNetworkLocation(),
excludedNodes));
assertEquals("excluded nodes with rack scope should be considered", 1,
cluster.countNumOfAvailableNodes(deadNode.getNetworkLocation(),
excludedNodes));
// adding the node in excluded scope to excluded list
excludedNodes.add(node2);
assertEquals("excluded nodes with ~ scope should be considered", 2,
cluster.countNumOfAvailableNodes("~" + deadNode.getNetworkLocation(),
excludedNodes));
// getting count with non-exist scope.
assertEquals("No nodes should be considered for non-exist scope", 0,
cluster.countNumOfAvailableNodes("/non-exist", excludedNodes));
// remove a node from the cluster
cluster.remove(node1);
assertEquals("1 node should be available", 1,
cluster.countNumOfAvailableNodes(NodeBase.ROOT, excludedNodes));
}
/**
* Test how well we pick random nodes.
*/
@Test
public void testChooseRandom() {
// create the topology
NetworkTopology cluster = new NetworkTopology();
NodeElement node1 = getNewNode("node1", "/d1/r1");
cluster.add(node1);
NodeElement node2 = getNewNode("node2", "/d1/r2");
cluster.add(node2);
NodeElement node3 = getNewNode("node3", "/d1/r3");
cluster.add(node3);
NodeElement node4 = getNewNode("node4", "/d1/r3");
cluster.add(node4);
// Number of iterations to do the test
int numIterations = 100;
// Pick random nodes
HashMap<String,Integer> histogram = new HashMap<String,Integer>();
for (int i=0; i<numIterations; i++) {
String randomNode = cluster.chooseRandom(NodeBase.ROOT).getName();
if (!histogram.containsKey(randomNode)) {
histogram.put(randomNode, 0);
}
histogram.put(randomNode, histogram.get(randomNode) + 1);
}
assertEquals("Random is not selecting all nodes", 4, histogram.size());
// Check with 99% confidence (alpha=0.01 as confidence = (100 * (1 - alpha)
ChiSquareTest chiSquareTest = new ChiSquareTest();
double[] expected = new double[histogram.size()];
long[] observed = new long[histogram.size()];
int j=0;
for (Integer occurrence : histogram.values()) {
expected[j] = 1.0 * numIterations / histogram.size();
observed[j] = occurrence;
j++;
}
boolean chiSquareTestRejected =
chiSquareTest.chiSquareTest(expected, observed, 0.01);
// Check that they have the proper distribution
assertFalse("Not choosing nodes randomly", chiSquareTestRejected);
// Pick random nodes excluding the 2 nodes in /d1/r3
histogram = new HashMap<String,Integer>();
for (int i=0; i<numIterations; i++) {
String randomNode = cluster.chooseRandom("~/d1/r3").getName();
if (!histogram.containsKey(randomNode)) {
histogram.put(randomNode, 0);
}
histogram.put(randomNode, histogram.get(randomNode) + 1);
}
assertEquals("Random is not selecting the nodes it should",
2, histogram.size());
}
private NodeElement getNewNode(String name, String rackLocation) {
NodeElement node = new NodeElement(name);
node.setNetworkLocation(rackLocation);
return node;
}
}