Nginx가 폴링 알고리즘을 구현하는 방법

public class simplepolling {

  /**
   * key是ip
   */
  public static list <string> ipservice = new linkedlist <>();
  static {
    ipservice.add("192.168.1.1");
    ipservice.add("192.168.1.2");
    ipservice.add("192.168.1.3");
  }
  public static int pos = 0;
  public static string getip(){
    if(pos >= ipservice.size()){
      //防止索引越界
      pos = 0;
    }
    string ip = ipservice.get(pos);
    pos ++;
    return ip;

  }

  public static void main(string[] args) {
    for (int i = 0; i < 4; i++) {
      system.out.println(getip());

    }
  }
}

public class weightpolling {

  /**
   * key是ip,value是权重
   */
  public static map<string, integer> ipservice = new linkedhashmap<>();
  static {
    ipservice.put("192.168.1.1", 5);
    ipservice.put("192.168.1.2", 1);
    ipservice.put("192.168.1.3", 1);
  }
  public static int requestid = 0;
  public static int getandincrement() {
    return requestid++;
  }

  public static string getip(){
    //获取总的权重
    int totalweight =0;
    for (integer value : ipservice.values()) {
      totalweight+= value;
    }
    //获取当前轮询的值
    int andincrement = getandincrement();
    int pos = andincrement% totalweight;
    for (string ip : ipservice.keyset()) {
      if(pos < ipservice.get(ip)){
        return ip;
      }
      pos -= ipservice.get(ip);
    }
    return null;
  }

  public static void main(string[] args) {
    for (int i = 0; i < 7; i++) {
      system.out.println(getip());
    }
  }

}

public class polling {

  /**
   * key是ip,value是权重
   */
  public static map <string,integer> ipservice = new linkedhashmap <>();
  static {
    ipservice.put("192.168.1.1",5);
    ipservice.put("192.168.1.2",1);
    ipservice.put("192.168.1.3",1);
  }
  private static map<string,weight> weightmap = new linkedhashmap <>();

  public static string getip(){
    //计算总的权重
     int totalweight = 0;
    for (integer value : ipservice.values()) {
      totalweight+=value;
    }
    //首先判断weightmap是否为空
    if(weightmap.isempty()){
      ipservice.foreach((ip,weight)->{
        weight weights = new weight(ip, weight,0);
        weightmap.put(ip,weights);
      });
    }
    //给map中得对象设置当前权重
    weightmap.foreach((ip,weight)->{
      weight.setcurrentweight(weight.getweight() + weight.getcurrentweight());
    });

    //判断最大权重是否大于当前权重,如果为空或者小于当前权重，则把当前权重赋值给最大权重
    weight maxweight = null;
    for (weight weight : weightmap.values()) {
      if(maxweight ==null || weight.getcurrentweight() > maxweight.getcurrentweight()){
        maxweight = weight;
      }
    }
    //最后把当前最大权重减去总的权重
    maxweight.setcurrentweight(maxweight.getcurrentweight() - totalweight);
    //返回
    return maxweight.getip();
  }

  public static void main(string[] args) {
    //模拟轮询7次取ip
    for (int i = 0; i < 7; i++) {
      system.out.println(getip());
    }
  }

}

class weight{
  /**
   * ip
   */
  private string ip;
  /**
   * 设置得权重
   */
  private int weight;
  /**
   * 当前权重
   */
  private int currentweight;

  public weight(string ip, int weight,int currentweight) {
    this.ip = ip;
    this.weight = weight;
    this.currentweight = currentweight;
  }

  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 getcurrentweight() {
    return currentweight;
  }

  public void setcurrentweight(int currentweight) {
    this.currentweight = currentweight;
  }
}