架构师训练营第 5 周作业

public class Node {
    private String name;
    private String ip;
    private int numOfKV;
    public Node(String name, String ip) {
        this.name = name;
        this.ip = ip;
        this.numOfKV = 0;
    }
    public String getName(){
        return this.name;
    }
    public String getIp(){
        return this.ip;
    }
    public void addKV(){
        this.numOfKV ++;
    }
    public int getNumOfKV(){
        return this.numOfKV;
    }
}

import java.util.List;
import java.util.SortedMap;
import java.util.TreeMap;
public class ConsistentHash {
    // Virtual Nodes
    private SortedMap<Integer, Node> vnodes;
    // Server Node
    private List<Node> nodes;
    // Number of virtual nodes per server node
    private int numPerNode;
    public ConsistentHash(List<Node> nodes, int numPerNode){
        this.nodes = nodes;
        this.numPerNode = numPerNode;
        init();
    }
    private void init(){
        this.vnodes = new TreeMap<Integer, Node>();
        // Generate virtual nodes
        for(Node node : nodes) {
            for (int i = 0; i < numPerNode; i++) {
                int hashCode = getHash("NODE-" + node.getIp() + "-V-" + i);
                vnodes.put(hashCode, node);
                // System.out.println("Virtual Node hash: " + hashCode + " of " + node.getName() + " has been added.");
            }
        }
    }
    public Node getNode(String key){
        int hashCode = getHash(key);
        SortedMap<Integer, Node> tail = this.vnodes.tailMap(hashCode);
        Node node = null;
        if(tail.size() == 0) {
            node = vnodes.get(this.vnodes.firstKey());
        } else {
            node = tail.get(tail.firstKey());
        }
        if(node != null) {
            node.addKV();
        }
        return node;
    }
    // FNV1_32_HASH
    private static int getHash(String str) {
        // int hash = str.hashCode();
      
       final int p = 16777619;
       int hash = (int) 2166136261L;
       for (int i = 0; i < str.length(); i++) {
           hash = (hash ^ str.charAt(i)) * p;
       }
       hash += hash << 13;
       hash ^= hash >> 7;
       hash += hash << 3;
       hash ^= hash >> 17;
       hash += hash << 5;
       if (hash < 0) {
           hash = Math.abs(hash);
       }
       return hash;
   }
}

import java.util.ArrayList;
import java.util.List;
public class ConsistentHashTest {
    public static void main(String[] args){
        final int numOfNodes = 10;
        final int numPerNode = 150;
        final int numOfKV = 1000000;
        String name;
        String ip;
        
        List<Node> servers = new ArrayList<Node>();
        for (int i = 0; i < numOfNodes; i++) {
            name = String.format("Server_%d", i);
            ip = String.format("192.168.0.%d", i);
            Node node = new Node(name, ip);
            servers.add(node);
        }
        ConsistentHash conHash = new ConsistentHash(servers, numPerNode);
        for (int n = 0; n < numOfKV; n++){
            String key = String.format("Client_%d", n);
            Node server = conHash.getNode(key);
            // System.out.println(key + " has been put into " + server.getName());
        }
        // Calculate average KV of Server
        double average = numOfKV/numOfNodes;
        double std = 0;
        for (int i = 0; i < servers.size(); i++) {
            Node server = servers.get(i);
            System.out.println("Server " + server.getName() + ": " + server.getNumOfKV());
            std += Math.pow((server.getNumOfKV() - average), 2);          
        }
        // Calculate standard devition
        std = Math.sqrt((std/(numOfNodes - 1)));
        System.out.println("Standard Devition: " + std);
    }
}

Server Server_0: 99099
Server Server_1: 106255
Server Server_2: 105439
Server Server_3: 89404
Server Server_4: 94323
Server Server_5: 102657
Server Server_6: 103662
Server Server_7: 97813
Server Server_8: 100095
Server Server_9: 101253
Standard Devition: 5173.1678238129225