通過Java實現反向代理叢集服務的平滑分配

2022-04-15 10:05:07

1.理解全過程

1.1.概述

需要具備的知識

Socket網路程式設計
反向代理的理解
平滑加權輪詢演演算法的理解
執行緒池的理解

目的：實現Socket 叢集服務的平滑加權輪詢負載。

業務實現：使用者端通過使用者名稱來查詢叢集服務中的使用者資訊。

1.2.整個流程

使用者端發起Socket請求給反向代理的Socket服務（使用者端並不知道伺服器端是反向代理伺服器）
反向代理伺服器接收到Socket服務請求
執行緒池開啟服務執行緒去處理請求
執行緒服務通過平滑加權輪詢演演算法尋找當前權重最高的下游服務
通過負載均衡演演算法返回的服務節點資訊來建立Socket請求
反向代理伺服器使用使用者端資訊，發起Socket請求給下游服務
Socket叢集服務節點收到Socket請求，查詢使用者資訊，再將處理結果返回給反向代理伺服器
反向代理伺服器再將結果返回給使用者端。

幾個細節點

使用反向代理服務，對使用者端無感，使用者端並不知道具體存取了哪個真實伺服器；
反向代理伺服器每次存取下游服務失敗時，就會降低該下游伺服器器的有效權重；每次存取下游服務成功時，就會提高該下游伺服器的有效權重（不超過設定的權重值）；
平滑加權輪詢演演算法會對宕機服務降權和提權，起到”剔除“宕機服務和緩衝恢復宕機服務的效果；
反向代理伺服器重啟後，所有設定恢復為設定引數；
反向代理伺服器使用執行緒池釋出Socket服務，支援多個使用者端同時請求同時分發。

2.程式碼實現

2.1.節點類

用於儲存服務節點相關資訊

package com.yty.proxy.lba;


public class Node implements Comparable<Node>{
    private String ip;
    private Integer port;
    private final Integer weight;
    private Integer effectiveWeight;
    private Integer currentWeight;
    // 預設權重為：1
    public Node(String ip,Integer port){
        this(ip,port,1);
    }

    public Node(String ip,Integer port, Integer weight){
        this.ip = ip;
        this.port = port;
        this.weight = weight;
        this.effectiveWeight = weight;
        this.currentWeight = weight;
    }

    public String getIp() {
        return ip;
    }

    public void setIp(String ip) {
        this.ip = ip;
    }

    public Integer getPort() {
        return port;
    }

    public void setPort(Integer port) {
        this.port = port;
    }

    public Integer getWeight() {
        return weight;
    }

    public Integer getEffectiveWeight() {
        return effectiveWeight;
    }

    public void setEffectiveWeight(Integer effectiveWeight) {
        this.effectiveWeight = effectiveWeight;
    }

    public Integer getCurrentWeight() {
        return currentWeight;
    }

    public void setCurrentWeight(Integer currentWeight) {
        this.currentWeight = currentWeight;
    }
    // 每成功一次，恢復有效權重1，不超過設定的起始權重
    public void onInvokeSuccess(){
        if(effectiveWeight < weight) effectiveWeight++;
    }
    // 每失敗一次，有效權重減少1，無底線的減少
    public void onInvokeFault(){
        effectiveWeight--;
    }

    @Override
    public int compareTo(Node node) {
        return currentWeight > node.currentWeight ? 1 : (currentWeight.equals(node.currentWeight) ? 0 : -1);
    }

    @Override
    public String toString() {
        return "Node{" +
                "ip='" + ip + ''' +
                ", port=" + port +
                ", weight=" + weight +
                ", effectiveWeight=" + effectiveWeight +
                ", currentWeight=" + currentWeight +
                '}';
    }
}

2.2.代理設定類

一般都是放在組態檔中設定，然後讀取指定key的組態檔資訊來完成設定。模擬為了簡單就直接寫程式碼裡了。

package com.yty.proxy;

import com.yty.proxy.lba.Node;

import java.util.ArrayList;
import java.util.List;

public class ProxyConfig {

    private static List<Node> nodes = new ArrayList<>();
    // 在組態檔中讀取：節點集合資訊。如果在同一臺伺服器測試，那就將ip配成一樣
    static {
        nodes.add(new Node("192.168.233.100",8001,2));
        nodes.add(new Node("127.0.0.1",8002,5));
        nodes.add(new Node("127.0.0.1",8003,3));
    }
    public static List<Node> getProxyConfig(){
        return nodes;
    }
}

2.3.負載均衡演演算法介面

package com.yty.proxy.lba;

public interface Robin {

    Node selectNode();
}

2.4.平滑加權輪詢演演算法

詳細介紹可以閱讀前兩篇負載均衡演演算法的文章

package com.yty.proxy.lba;

import com.yty.proxy.ProxyConfig;
import java.util.List;

/**
 * 加權輪詢演演算法：平滑加權輪詢演演算法
 */
public class WeightedRoundRobin implements Robin {

    private static List<Node> nodes;
    // 讀取設定資訊
    static {
        nodes = ProxyConfig.getProxyConfig();
    }
    /**
     * 按照當前權重（currentWeight）最大值獲取IP
     * @return Node
     */
    public Node selectNode(){
        if (nodes ==null || nodes.size()<=0) return null;
        if (nodes.size() == 1)  return nodes.get(0);

        // 權重之和
        Integer totalWeight = 0;
        for(Node node : nodes){
            totalWeight += node.getEffectiveWeight();
        }

        synchronized (nodes){
            // 選出當前權重最大的節點
            Node nodeOfMaxWeight = null;
            for (Node node : nodes) {
                if (nodeOfMaxWeight == null)
                    nodeOfMaxWeight = node;
                else
                    nodeOfMaxWeight = nodeOfMaxWeight.compareTo(node) > 0 ? nodeOfMaxWeight : node;
            }
            // 平滑負載均衡
            nodeOfMaxWeight.setCurrentWeight(nodeOfMaxWeight.getCurrentWeight() - totalWeight);
            nodes.forEach(node -> node.setCurrentWeight(node.getCurrentWeight()+node.getEffectiveWeight()));
            return nodeOfMaxWeight;
        }
    }

}

2.5.代理服務執行緒類

用於處理代理服務請求的執行緒類，不同請求建立不同執行緒來處理

package com.yty.proxy;

import java.io.*;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class ProxyServerThread implements Runnable {
    private Socket proxySocket;
    private OutputStream proxyOut;
    private InputStream proxyIn;
    private Socket socket;
    private OutputStream serverOut;
    private InputStream serverIn;
    public ProxyServerThread(Socket proxySocket) throws IOException {
        this.proxySocket = proxySocket;
        this.proxySocket.setSoTimeout(6000);
        this.proxyOut = proxySocket.getOutputStream();
        this.proxyIn = proxySocket.getInputStream();
    }

    @Override
    public void run() {
        try {
            this.proxyService();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            this.close();
        }
    }

    private void proxyService() throws IOException {
        // 代理接收使用者端請求
        byte[] proxyDataBytes =null;
        proxyDataBytes = getData(proxyIn);
        System.out.println("代理收到請求資料："+new String(proxyDataBytes));
        if (proxyDataBytes == null){
            proxyOut.write("請求內容異常".getBytes());
        }

        byte[] serverData = this.dispatcherService(proxyDataBytes);

        // 代理響應使用者端
        assert serverData != null;
        proxyOut.write(serverData);
        proxySocket.shutdownOutput();
        System.out.println("代理響應使用者端資料："+new String(proxyDataBytes));
    }

    private byte[] dispatcherService(byte[] proxyDataBytes){
        // 選擇節點：傳送請求和接收響應資訊
        Robin wrr = new WeightedRoundRobin();
        Node node = wrr.selectNode();
        byte[] serverData = null;
        try {
            this.socket = new Socket(node.getIp(), node.getPort());
            socket.setSoTimeout(6000);
            serverIn = socket.getInputStream();
            serverOut= socket.getOutputStream();
            serverOut.write(proxyDataBytes);
            socket.shutdownOutput();
            serverData = getData(serverIn);
            System.out.println("真實伺服器端響應資料："+ new String(serverData));
            node.onInvokeSuccess();//提權
        } catch (IOException e) {
            node.onInvokeFault();//降權
            serverData = "代理的下游伺服器異常".getBytes();
        }
        System.out.println("負載均衡到：" + node);
        return serverData;
    }

    private byte[] getData(InputStream in) throws IOException {
        List<Byte> byteList = new ArrayList<>();
        int temp = -1;
        while (true) {
            temp = in.read();
            if (temp != -1)
                byteList.add((byte) temp);
            else
                break;
        }
        byte[] bytes = new byte[byteList.size()];
        for (int i=0;i<byteList.size();i++){
            bytes[i]=byteList.get(i);
        }
        return bytes;
    }

    private void close() {
        try {
            if (proxySocket!=null){
                proxySocket.shutdownInput();
                proxySocket.close();
            }
            if (socket!=null){
                socket.shutdownInput();
                socket.close();
            }
        }catch (IOException e){
            e.printStackTrace();
            System.out.println("代理服務關閉socket資源異常");
        }
    }
}

2.6.代理服務類

通過執行緒池來管理代理服務執行緒，不同的請求分發到不同執行緒處理。這裡用的是newCachedThreadPool 執行緒池。

代理伺服器在本地啟動。這裡也可以新建一個類來啟動服務，這樣可以啟動多個代理服務，這裡為了簡單就直接在本類的main方法啟動。可以對比後面的業務服務類，業務服務類就是這麼起的，因為要放到不同的伺服器啟動業務服務。

package com.yty.proxy;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ProxyServer {
    private final Integer port;
    private ServerSocket serverSocket;
    public ProxyServer(Integer port) {
        this.port = port;
    }

    public void start(){
        ExecutorService threadPool = Executors.newCachedThreadPool();
        try {
            serverSocket = new ServerSocket(port);
            while (true){
                Socket socket = serverSocket.accept();
                threadPool.execute(new ProxyServerThread(socket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    public static void main(String[] args) {
        Integer proxyPort=8000;
        ProxyServer proxyServer = new ProxyServer(proxyPort);
        System.out.println("開啟代理服務……");
        proxyServer.start();
    }
}

2.7.業務實體類

package com.yty.proxy.server;

public class MyUser {
    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public MyUser(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public MyUser() {
    }

    @Override
    public String toString() {
        return "{" +"name='" + name + ''' + ", age=" + age + '}';
    }
}

2.8.業務類

處理具體業務的類，通過使用者名稱稱簡單獲取資訊

package com.yty.proxy.server;

import java.util.ArrayList;
import java.util.List;

public class MyUserService {
    private static List<MyUser> list = new ArrayList<>();

    static{
        list.add(new MyUser("張三",18));
        list.add(new MyUser("張三丰",38));
        list.add(new MyUser("小白",18));
    }
    public MyUser findByUsername(String username){
        for (MyUser user:list){
            if (user.getName().equals(username)){
                return user;
            }
        }
        return null;
    }
}

2.9.業務服務執行緒類

用於處理業務服務請求的執行緒類，不同請求建立不同執行緒來處理

package com.yty.proxy.server;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class SocketServerThread implements Runnable {
    private Socket socket;
    private OutputStream serverOut;
    private InputStream serverIn;
    public SocketServerThread(Socket socket) throws IOException {
        this.socket = socket;
        socket.setSoTimeout(6000);
        this.serverOut = socket.getOutputStream();
        this.serverIn = socket.getInputStream();
    }

    @Override
    public void run() {
        try {
            this.service();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            this.close();
        }
    }
    private void service() throws IOException {
        // 接收使用者端請求
        byte[] dataBytes =null;
        dataBytes = getData(serverIn);
        if (dataBytes == null){
            serverOut.write("請求內容異常".getBytes());
        }
        String username = new String(dataBytes);
        System.out.println("收到請求資料："+username);

        // 具體業務程式碼
        MyUserService myUserService = new MyUserService();
        MyUser user = myUserService.findByUsername(new String(dataBytes));
        String serverData = "沒有查詢到使用者" + username + "的資料";
        if(user!=null){
            serverData = user.toString();
            serverOut.write(user.toString().getBytes());
        }
        System.out.println("響應使用者端資料：" + serverData);
    }

    private byte[] getData(InputStream in) throws IOException {
        List<Byte> byteList = new ArrayList<>();
        int temp = -1;
        while (true) {
            temp = in.read();
            if (temp != -1)
                byteList.add((byte) temp);
            else
                break;
        }
        byte[] bytes = new byte[byteList.size()];
        for (int i=0;i<byteList.size();i++){
            bytes[i]=byteList.get(i);
        }
        return bytes;
    }

    private void close() {
        try {
            if (socket!=null){
                socket.shutdownInput();
                socket.shutdownOutput();
                socket.close();
            }
        }catch (IOException e){
            e.printStackTrace();
            System.out.println("服務關閉socket資源異常");
        }
    }
}

2.10.業務服務類

通過執行緒池來管理業務服務執行緒，不同的請求分發到不同執行緒處理。這裡用的也是newCachedThreadPool 執行緒池。

package com.yty.proxy.server;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class SocketServer {
    private final Integer port;
    private ServerSocket serverSocket;
    private Integer threads = 3;


    public SocketServer(Integer port) {
        this.port = port;
    }

    public void start(){
        ExecutorService threadPool = Executors.newFixedThreadPool(threads);
        try {
            serverSocket = new ServerSocket(port);
            while (true){
                Socket socket = serverSocket.accept();
                threadPool.execute(new SocketServerThread(socket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

2.11.啟動三個業務服務(服務叢集)

本次測試是分在兩臺伺服器測試，1臺【192.168.233.100】、另外都是本地【127.0.0.1】。如果覺得麻煩，那就都配成本地【127.0.0.1】，然後起服務都在本地起。

服務1：在IP為192.168.233.100 的伺服器啟動

package com.yty.proxy.test;
import com.yty.proxy.server.SocketServer;
public class StartServer1 {
    public static void main(String[] args) {
        System.out.println("開啟後端服務8001……");
        new SocketServer(8001).start();
    }
}

服務2：在本地伺服器啟動

package com.yty.proxy.test;
import com.yty.proxy.server.SocketServer;
public class StartServer2 {
    public static void main(String[] args) {
        System.out.println("開啟後端服務8002……");
        new SocketServer(8002).start();
    }
}

服務3：在本地伺服器啟動

package com.yty.proxy.test;
import com.yty.proxy.server.SocketServer;
public class StartServer3 {
    public static void main(String[] args) {
        System.out.println("開啟後端服務8003……");
        new SocketServer(8003).start();
    }
}

2.12.使用者端

package com.yty.proxy.test;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class Client {
    public static void main(String[] args) throws IOException {
        String ip = "127.0.0.1";
        int port = 8000;
        Socket socket = new Socket(ip, port);
        socket.setSoTimeout(6000);
        OutputStream out = socket.getOutputStream();
        InputStream in = socket.getInputStream();
        // 傳送資料
        out.write("小白".getBytes());
        out.flush();
        socket.shutdownOutput();
        // 讀取資料
        byte[] data = new Client().getData(in);
        System.out.println("響應資料："+new String(data));
        out.close();
    }

    private byte[] getData(InputStream in) throws IOException {
        BufferedInputStream bin = new BufferedInputStream(in);
        List<Byte> byteList = new ArrayList<>();
        while (true) {
            int temp = bin.read();
            if (temp != -1)
                byteList.add((byte) temp);
            else
                break;
        }
        byte[] bytes = new byte[byteList.size()];
        for (int i=0;i<byteList.size();i++){
            bytes[i]=byteList.get(i);
        }
        return bytes;
    }
}