平滑加权轮询算法

平滑加权轮询算法及代码

参考文章：https://www.jianshu.com/p/836193df61db；写的很详细，我只能写点自己的理解。

事件：针对不同权重的不同服务器，进行选择，优先选择权重大的服务器
解决：为每台服务器设置id，权重，有效权重的属性
1.遍历服务器，为每台服务器设置id，权重，有效权重，使得有效权重与权重相同
2.获取当前有效权重最大的服务器，并计算权重和
3.使得当前有效权重最大服务器的有效权重减去总权重
4.使得每一台服务的有效权重设为当前权重加上有效权重
5.返回有效权重最大的服务器Id

理解：首先将获取当前最大的权重的服务器，然后减去总权重，
其次将有效权重，加上各服务器的权重，相当于服务器的当前权重和加上总权重
保证服务器的当前权重和不变。

四台服务器权重分别为1，2，3，4

　　　1　　 2 　　3 　　4
1 　　2　　  4　　 6　　 -2
2　　 3　  　6　　-1　　 2
3 　　4　　 -2　　 2 　　6
4　　 5　　 0　　  5 　　0
5 　　-4　　 2　　 8　　 4
6 　　-3　　 4　　 1　　 8
7 　　-2　　 6　　 4　　 2
8 　　-1 　　-2 　　7　　 6
9 　　0 　　0 　 　0 　　0
10 　 1　　  2 　　3  　　4

 代码如下

 服务器

package com.WeightService;

import java.util.List;

public class Service {
    public Service(String id, int weight, int weightNow) {
        this.id = id;
        this.weight = weight;
        this.weightNow = weightNow;
    }

    private String id;
    private int weight;
    private int weightNow;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public int getWeight() {
        return weight;
    }

    public void setWeight(int weight) {
        this.weight = weight;
    }

    public int getWeightNow() {
        return weightNow;
    }

    public void setWeightNow(int weightNow) {
        this.weightNow = weightNow;
    }
}

算法

package com.WeightService;


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

public class WeightService {

    public static void main(String[] args) {
        //总的任务
        System.out.println("输入轮询次数");
        Scanner sc = new Scanner(System.in);
        int total = sc.nextInt();
        //服务器
        int totalWeight = 0;
        System.out.println("输入服务器个数");
        Scanner test = new Scanner(System.in);
        int num = test.nextInt();
        List<Service> serviceList = new ArrayList<>();

        for (int i = 0; i < num; i++) {
            System.out.println("输入服务器" + i + "的权重");
            Scanner scanner = new Scanner(System.in);
            int weight = scanner.nextInt();
            totalWeight = totalWeight + weight;
            serviceList.add(i, new Service(i + "", weight, weight));
        }

        for (int i = 0; i < total; i++) {
            String server = getServer(serviceList, totalWeight);
            System.out.println(server);
        }
    }

    public static String getServer(List<Service> serviceList, int totalWeight) {
        Service maxWeightService = null;
        for (int i = 0; i < serviceList.size(); i++) {
            if (maxWeightService == null) {
                maxWeightService = serviceList.get(i);
            }
            if (serviceList.get(i).getWeightNow() > maxWeightService.getWeightNow()) {
                maxWeightService = serviceList.get(i);
            }
            System.out.println(i + "-->" + serviceList.get(i).getWeightNow());
        }
        String Id = maxWeightService.getId();
        serviceList.get(Integer.valueOf(Id).intValue()).setWeightNow(maxWeightService.getWeightNow() - totalWeight);
        System.out.println(totalWeight);
        for (int i = 0; i < serviceList.size(); i++) {

            Service service = serviceList.get(i);
            if (service != null) {
                service.setWeightNow(service.getWeightNow() + service.getWeight());
            }
        }
        return (maxWeightService.getId());
    }

}