第五周 实现一致性 hash 算法

package com.demo;
import java.util.HashSet;
import java.util.Set;
/******************************
 * 用途说明: 服务器节点
 * 作者姓名: chenshijie
 * 创建时间: 2020/10/24 02:02
 ******************************/
public class Node {
    private int nodeId;
    private Set<String> keys = new HashSet<String>();
    public Node(int nodeId) {
        this.nodeId = nodeId;
    }
    public void put(String key,String value){
        keys.add(key);
    }
    public int getSize() {
        return keys.size();
    }
    public int getNodeId() {
        return nodeId;
    }
    public void setNodeId(int nodeId) {
        this.nodeId = nodeId;
    }
    public Set<String> getKeys() {
        return keys;
    }
    public void setKeys(Set<String> keys) {
        this.keys = keys;
    }
}

package com.demo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/******************************
 * 用途说明: 节点管理器
 * 作者姓名: chenshijie
 * 创建时间: 2020/10/24 02:04
 ******************************/
public class NodeManager {
    private static final Logger LOGGER = LoggerFactory.getLogger(NodeManager.class);
    //虚拟节点数
    private static final int VM_NODE = 150;
    private static Map<Integer,Node> nodeMap = new HashMap<Integer, Node>();
    private List<Node> nodeList = new ArrayList<Node>();
    public void addNode(Node node) {
        nodeList.add(node);
        shuffer();
    }
    public Node getNodeByKey(String key) {
        int i = key.hashCode() & Integer.MAX_VALUE;
        int nodeIndex = i % VM_NODE;
        Node node = nodeMap.get(nodeIndex);
        LOGGER.debug("node:{}, nodeIndex:{}, i:{}",node,nodeIndex,i);
        return node;
    }
    public int[] info() {
        int[] rs = new int[nodeList.size()];
        for(int i =0;i< nodeList.size();i++) {
            Node node = nodeList.get(i);
            rs[i] = node.getSize();
            LOGGER.info("node id:{}, key size:{}",node.getNodeId(),node.getSize());
        }
        return rs;
    }
    private void shuffer() {
        nodeMap.clear();
        for(int i = 0; i < VM_NODE; i++) {
            int nodeIndex = i % nodeList.size();
            nodeMap.put(i,nodeList.get(nodeIndex));
        }
        LOGGER.debug("shuffer finish:map.size:{},map:{}",nodeMap.size(),nodeMap);
    }
}

package com.demo;
/******************************
 * 用途说明: 客户端
 * 作者姓名: chenshijie
 * 创建时间: 2020/10/24 02:03
 ******************************/
public class Client {
    private NodeManager nodeManager;
    public Client(NodeManager nodeManager) {
        this.nodeManager = nodeManager;
    }
    public void put(String key,String value) {
        Node node = nodeManager.getNodeByKey(key);
        node.put(key,value);
    }
}

package com.demo;
/******************************
 * 用途说明: 标准差计算
 * 作者姓名: chenshijie
 * 创建时间: 2020/10/24 17:27
 ******************************/
public class StandardDiviation {
    public static double StandardDiviation(int[] x) {
        int m=x.length;
        double sum=0;
        for(int i=0;i<m;i++){//求和
            sum+=x[i];
        }
        double dAve=sum/m;//求平均值
        double dVar=0;
        for(int i=0;i<m;i++){//求方差
            dVar+=(x[i]-dAve)*(x[i]-dAve);
        }
        return Math.sqrt(dVar/m);
    }
}

package com.demo;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.UUID;
/******************************
 * 用途说明: 单元测试
 * 作者姓名: chenshijie
 * 创建时间: 2020/10/24 02:04
 ******************************/
public class ClientTest {
    private static final Logger LOGGER = LoggerFactory.getLogger(ClientTest.class);
    @Test
    public void put() {
        NodeManager nodeManager = new NodeManager();
        for(int i =1;i<=10;i++) {
            Node node = new Node(i);
            nodeManager.addNode(node);
        }
        Client client = new Client(nodeManager);
        for(int i = 0; i<1000000; i++) {
            String key = System.currentTimeMillis() + UUID.randomUUID().toString().replace("-", "");
            client.put(key,null);
        }
        int[] info = nodeManager.info();
        double v = StandardDiviation.StandardDiviation(info);
        LOGGER.info("标准差={}",v);
    }
}