Java tutorial
/** * 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; } }