package cn.minoa.dataRequestInterface;

/**
 * @author mac
 * @description
 *              拥塞窗口
 * @date 2020-03-24 10:25
 */
public class CongestionWindow {

    //拥塞窗口大小
    private Double cwnd;

    //表示当前正在发送的数据,发送一条数据需要加一，收到成功恢复需要减一
    private Double inFlight;

    //拥塞窗口阈值
    private Double thresh;

    //下一次窗口减小的界限
    private Integer nSupress = 0;

    //收到数据包的数量，收到一个数据包进行加一操作
    private Long nIndata = 0l;

    //发送兴趣包的数量，发出一个兴趣包进行加一操作
    private Long nOutInterest = 0l;

    //更新nsupress时的一个比率
    private static Double rate = 0.5d;

    public CongestionWindow(){
        this.cwnd = 4d;
        this.thresh = 300d;
        this.inFlight = 0d;
    }
    public CongestionWindow(Double cwnd, Double thresh, Double inFlight){
        this.inFlight = inFlight;
        this.cwnd = cwnd;
        this.thresh = thresh;
    }

    /**
     * 当前窗口是否为空
     * @return
     */
    public boolean empty(){
        boolean res = false;
        synchronized (this){
            if (inFlight == 0){
                res = true;
            }
        }
        return res;
    }

    /**
     * 当前窗口是否已满
     * @return
     */
    public boolean full(){
        boolean res = false;
        synchronized (this){
            if(cwnd == inFlight){
                res = true;
            }
        }
        return res;
    }

    /**
     * 获取当前还能发送多少数据
     * 如果不能发送数据，返回值为0
     * @return
     */
    public int getAvailableCwnd(){
        int res = 0;
        synchronized (this){
            if(inFlight >= cwnd){
                res = 0;
            }else{
                res = (int)(cwnd - inFlight);
            }
        }
        return res;
    }


    /**
     * 在onData函数中
     * 收到一个数据包，执行加一操作，需要加锁
     */
    public void  nIndataIncrease(){
        synchronized (this){
            nIndata++;
        }
    }

    /**
     * 发出一个兴趣包，执行加一操作，不需要加锁
     */
    public void nOutInterestIncrease(){
        nOutInterest++;
    }

    /**
     * inFlight加一
     */
    public void inFlightIncrease(){
        synchronized (this){
            this.inFlight++;
        }
    }

    public void inFlightIncrease(int inFlight){
        synchronized (this){
            this.inFlight += inFlight;
        }
    }

    /**
     * inFliehgt减一
     */
    public void inFlightDecrease(){
        synchronized (this){
            this.inFlight--;
        }
    }
    public void inFlightDecrease(int inFlight){
        synchronized (this){
            this.inFlight -= inFlight;
        }
    }

    /**
     * 增加拥塞窗口的值
     *
     */
    public void cwndIncrease(){

        synchronized (this){
            if(this.cwnd < this.thresh){
                //慢开始算法
                this.cwnd += 1;
                /*if(this.cwnd > this.thresh){
                    this.thresh = this.cwnd;
                }*/
            }else{
                //拥塞避免算法
                this.cwnd += (1.0/this.cwnd);
            }
        }
        System.out.println("-----------------------------------------cwnd:" + cwnd + ", thresh:" + thresh);
    }

    /**
     * 减少拥塞窗口的值
     * 每当检测到拥塞时，就需要执行此函数
     */
    public void cwndDecrease(){
        synchronized (this){
            if(nIndata >= nSupress){
//                this.thresh = Math.floor(this.cwnd/2);
                this.thresh = this.cwnd/2;
                this.cwnd = this.thresh;
                nSupress = (int)(nOutInterest + rate*(nOutInterest - nIndata));
            }
        }
        System.out.println("-----------------------------------------cwnd:" + cwnd + ", thresh:" + thresh);
    }


    /**
     * 设置拥塞窗口大小
     * @param cwnd
     */
    public void setCwnd(Double cwnd){
        synchronized (this){
            this.cwnd = cwnd;
        }
    }

    /**
     * 获得当前拥塞窗口大小
     * @return
     */
    public Integer getCwnd(){

        int res = 0;
        synchronized (this){
            res = this.cwnd.intValue();
        }
        return res;

    }

    @Override
    public String toString() {
        return "CongestionWindow {" +
                "cwnd=" + cwnd +
                ", inFlight=" + inFlight +
                ", thresh=" + thresh +
                '}';
    }

}