架构师训练营第五周作业

    <dependencies>        <!-- https://mvnrepository.com/artifact/com.google.guava/guava -->        <dependency>            <groupId>com.google.guava</groupId>            <artifactId>guava</artifactId>            <version>28.1-jre</version>        </dependency>        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->        <dependency>            <groupId>org.projectlombok</groupId>            <artifactId>lombok</artifactId>            <version>1.18.12</version>            <scope>provided</scope>        </dependency>    </dependencies>

import lombok.AllArgsConstructor;import lombok.Data;import lombok.NoArgsConstructor;import lombok.ToString;
@Data@NoArgsConstructor@AllArgsConstructor@ToStringclass Node {    String ip;    String name;}

import com.google.common.base.Charsets;import lombok.Data;import lombok.NoArgsConstructor;
import java.util.SortedMap;import java.util.TreeMap;
import static com.google.common.hash.Hashing.murmur3_32;
@Data@NoArgsConstructorpublic class ConsistentHash {
    private int virtualNum;    private final TreeMap<Integer, Node> virtualNodes = new TreeMap<>();
    private int getHashCode(Node node, int number) {        return getHashCode(node.toString() + "-" + number);    }
    private int getHashCode(String key) {        return murmur3_32().hashString(key, Charsets.UTF_8).asInt();    }
    public void add(Node node) {        for (int i = 0; i < virtualNum; i++) {            virtualNodes.put(getHashCode(node, i), node);        }    }
    public void remove(Node node) {        for (int i = 0; i < virtualNum; i++) {            virtualNodes.remove(getHashCode(node, i));        }    }
    public Node get(String key) {        if (virtualNodes.isEmpty()) {            return null;        }        int hashcode = getHashCode(key);        int nodeHashcode;        if (virtualNodes.containsKey(hashcode)) {            nodeHashcode = hashcode;        } else {            SortedMap<Integer, Node> tailMap = virtualNodes.tailMap(hashcode);            nodeHashcode = tailMap.isEmpty() ? virtualNodes.firstKey() : tailMap.firstKey();        }        return virtualNodes.get(nodeHashcode);    }}

package com.example;
import java.util.*;import java.util.stream.Collectors;import java.util.stream.IntStream;
public class Main {
    public static List<Node> initNodes(int nodeNumber) {        String ipPrefix = "172.10.0.";        List<Node> nodes = IntStream.range(0, nodeNumber).mapToObj(i -> {            String ip = ipPrefix + i;            String name = "node-" + i;            return new Node(ip, name);        }).collect(Collectors.toList()); // 节点//        nodes.forEach(System.out::println); // print        return nodes;    }
    public static ConsistentHash initConsistentHash(List<Node> nodes, int virtualNumber) {        ConsistentHash consistentHash = new ConsistentHash();        consistentHash.setVirtualNum(virtualNumber);        nodes.forEach(consistentHash::add);        return consistentHash;    }
    public static double standardDeviation(Collection<Integer> list) {        Double avg = list.stream().mapToDouble(Integer::doubleValue).average().orElse(0D); // 平均        int total = list.stream().mapToInt(num -> (int) ((num - avg) * (num - avg))).sum(); //  方差        return Math.sqrt(total);    }
    public static void testVirtual(int totalNode, int perVirtualNode) {        List<Node> nodes = initNodes(totalNode); //10节点
        Map<String, Integer> counts = new HashMap<>();        nodes.forEach(node -> {            String ip = node.getIp();            counts.put(ip, 0);        }); // 初始化计数
        ConsistentHash consistentHash = initConsistentHash(nodes, perVirtualNode); // 初始化虚拟节点
        for (int i = 0; i < 1000000; i++) {            String randomKey = UUID.randomUUID().toString();            Node node = consistentHash.get(randomKey);            counts.put(node.getIp(), counts.get(node.getIp()) + 1);        }
//        counts.forEach((k, v) -> {//            System.out.println(k + " -> " + v);//        });
        System.out.println(perVirtualNode + " virtualNode: " + standardDeviation(counts.values()));
    }    public static void main(String[] args) {        testVirtual(10, 50);        testVirtual(10, 100);        testVirtual(10, 150);        testVirtual(10, 200);        testVirtual(10, 250);    }}