Ketama Hashing Algorithm

import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Random; public class HashAlgorithmPercentTest { static Random ran = new Random(); /** key's count */ private static final Integer EXE_TIMES = 100000; private static final Integer NODE_COUNT = 50; private static final Integer VIRTUAL_NODE_COUNT = 160; static List<String> allKeys = null; static { allKeys = getAllStrings(); } public static void main(String[] args) { Map<String, List<Node>> map = generateRecord(); List<Node> allNodes = getNodes(NODE_COUNT); System.out.println("Normal case : nodes count : " + allNodes.size()); call(allNodes, map); allNodes = getNodes(NODE_COUNT + 8); System.out.println("Added case : nodes count : " + allNodes.size()); call(allNodes, map); allNodes = getNodes(NODE_COUNT - 10); System.out.println("Reduced case : nodes count : " + allNodes.size()); call(allNodes, map); int addCount = 0; int reduceCount = 0; for (Map.Entry<String, List<Node>> entry : map.entrySet()) { List<Node> list = entry.getValue(); if (list.size() == 3) { if (list.get(0).equals(list.get(1))) { addCount++; } if (list.get(0).equals(list.get(2))) { reduceCount++; } } else { System.out.println("It's wrong size of list, key is " + entry.getKey() + ", size is " + list.size()); } } System.out.println(addCount + " --- " + reduceCount); System.out.println("Same percent in added case : " + (float) addCount * 100/ EXE_TIMES + "%"); System.out.println("Same percent in reduced case : " + (float) reduceCount * 100/ EXE_TIMES + "%"); } private static void call(List<Node> nodes, Map<String, List<Node>> map) { KetamaNodeLocator locator = new KetamaNodeLocator(nodes, HashAlgorithm.KETAMA_HASH, VIRTUAL_NODE_COUNT); for (Map.Entry<String, List<Node>> entry : map.entrySet()) { Node node = locator.getPrimary(entry.getKey()); if (node != null) { List<Node> list = entry.getValue(); list.add(node); } } } private static Map<String, List<Node>> generateRecord() { Map<String, List<Node>> record = new HashMap<String, List<Node>>(EXE_TIMES); for (String key : allKeys) { List<Node> list = record.get(key); if (list == null) { list = new ArrayList<Node>(); record.put(key, list); } } return record; } /** * Gets the mock node by the material parameter * * @param nodeCount * the count of node wanted * @return * the node list */ private static List<Node> getNodes(int nodeCount) { List<Node> nodes = new ArrayList<Node>(); for (int k = 1; k <= nodeCount; k++) { Node node = new Node("node" + k); nodes.add(node); } return nodes; } /** * All the keys */ private static List<String> getAllStrings() { List<String> allStrings = new ArrayList<String>(EXE_TIMES); for (int i = 0; i < EXE_TIMES; i++) { allStrings.add(generateRandomString(ran.nextInt(50))); } return allStrings; } /** * To generate the random string by the random algorithm * <br> * The char between 32 and 127 is normal char * * @param length * @return */ private static String generateRandomString(int length) { StringBuffer sb = new StringBuffer(length); for (int i = 0; i < length; i++) { sb.append((char) (ran.nextInt(95) + 32)); } return sb.toString(); } }