權重輪詢調度算法(WeightedRound-RobinScheduling)-Java實現2

 

權重輪詢調度算法(WeightedRound-RobinScheduling)-Java實現
                                      ----參考Nginx中負載均衡算法實現


與上一遍博客 http://www.cnblogs.com/huligong1234/p/3819979.html 中實現方式不同，
這里主要參考這篇文章的實現： Nginx 負載均衡-加權輪詢策略剖析 http://www.cnblogs.com/dyllove98/archive/2013/07/13/3188450.html，
與上一遍中實現比起來，效果比較好，權重比較低的服務器，也比較容易背獲取到，但請求數量比較大的時候，兩個實現方式中，每個服務器分擔的請求數基本無差別，區別主要是順序上。
本篇文章也加上了動態添加服務器，和動態down掉服務器的演示實例。 由於研究本算法的目的是在其他方面的應用，故涉及服務器請求超時時間等因素，並未考慮。

 

import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

/**
 * 權重輪詢調度算法(WeightedRound-RobinScheduling)-Java實現
 * @author huligong
 * */
public class WeightedRoundRobinScheduling {

    private List<Server> serverList; //服務器集合

    public Server GetBestServer() {
        Server server = null;
        Server best = null;
        int total = 0;
        for(int i=0,len=serverList.size();i<len;i++){
            //當前服務器對象
            server = serverList.get(i);

            //當前服務器已宕機，排除
            if(server.down){
                continue;
            }

            server.currentWeight += server.effectiveWeight;
            total += server.effectiveWeight;
            
            if(server.effectiveWeight < server.weight){
                server.effectiveWeight++;
            }
            
            if(best == null || server.currentWeight>best.currentWeight){
                best = server;
            }
            
        }

        if (best == null) {
            return null;
        }

        best.currentWeight -= total;
        best.checkedDate = new Date();
        return best;
    }
    
    

    class Server {
        public String ip;
        public int weight;
        public int effectiveWeight;
        public int currentWeight;
        public boolean down = false;
        public Date checkedDate;
        public Server(String ip, int weight) {
            super();
            this.ip = ip;
            this.weight = weight;
            this.effectiveWeight = this.weight;
            this.currentWeight = 0;
            if(this.weight < 0){
                this.down = true;
            }else{
                this.down = false;
            }
        }
        public String getIp() {
            return ip;
        }
        public void setIp(String ip) {
            this.ip = ip;
        }
        public int getWeight() {
            return weight;
        }
        public void setWeight(int weight) {
            this.weight = weight;
        }
        public int getEffectiveWeight() {
            return effectiveWeight;
        }
        public void setEffectiveWeight(int effectiveWeight) {
            this.effectiveWeight = effectiveWeight;
        }
        public int getCurrentWeight() {
            return currentWeight;
        }
        public void setCurrentWeight(int currentWeight) {
            this.currentWeight = currentWeight;
        }
        public boolean isDown() {
            return down;
        }
        public void setDown(boolean down) {
            this.down = down;
        }
        public Date getCheckedDate() {
            return checkedDate;
        }
        public void setCheckedDate(Date checkedDate) {
            this.checkedDate = checkedDate;
        }
        
    }
    

    public void init() {
        Server s1 = new Server("192.168.0.100", 3);//3
        Server s2 = new Server("192.168.0.101", 2);//2
        Server s3 = new Server("192.168.0.102", 6);//6
        Server s4 = new Server("192.168.0.103", 4);//4
        Server s5 = new Server("192.168.0.104", 1);//1
        Server s6 = new Server("192.168.0.105", 0);//0
        Server s7 = new Server("192.168.0.106", 0);//0
        Server s8 = new Server("192.168.0.107", 0);//0
        Server s9 = new Server("192.168.0.108", 0);//0
        serverList = new ArrayList<Server>();
        serverList.add(s1);
        serverList.add(s2);
        serverList.add(s3);
        serverList.add(s4);
        serverList.add(s5);
        serverList.add(s6);
        serverList.add(s7);
        serverList.add(s8);
        serverList.add(s9);
    }
    
    public void add(int i) {
        Server s = new Server("192.168.0.1"+i, i-15);
        serverList.add(s);
    }
    
    public Server getServer(int i) {
        if(i<serverList.size()){
            return serverList.get(i);
        }
       return null;
    }
    
    
    public static void main(String[] args) {
        WeightedRoundRobinScheduling obj = new WeightedRoundRobinScheduling();
        obj.init();
        
        Map<String,Integer> countResult = new HashMap<String,Integer>();
        
        for (int i = 0; i < 100; i++) {
            Server s = obj.GetBestServer();
            String log = "ip:"+s.ip+";weight:"+s.weight;
            if(countResult.containsKey(log)){
                countResult.put(log,countResult.get(log)+1);
            }else{
                countResult.put(log,1);
            }
            System.out.println(log);
        
            //動態添加服務器
            if(i==20 || i==22){
                  obj.add(i);
            }
            
            //動態停止服務器
            if(i==30){
                obj.getServer(2).setDown(true);
                obj.getServer(3).setDown(true);
          }
        }
        
        for(Entry<String, Integer> map : countResult.entrySet()){
            System.out.println("服務器 "+map.getKey()+" 請求次數： "+map.getValue());
        }
    }

}