限流算法

应用场景

• 需要限制某个用户的行为
• 接口调用过于频繁

实现的几种方式

1、

代码示例

import redis.clients.jedis.Jedis;
import redis.clients.jedis.Pipeline;
import redis.clients.jedis.Response;

public class SimpleRateLimiter {

    private Jedis jedis;

    public SimpleRateLimiter(Jedis jedis) {
        this.jedis = jedis;
    }

    public boolean isActionAllowed(String userId, String actionKey, int period, int maxCount){
        String key = String.format("hist:%s:%s", userId, actionKey);
        long nowTs = System.currentTimeMillis();
        Pipeline pipe = jedis.pipelined();
        pipe.multi();
        pipe.zadd(key,nowTs,""+nowTs);
        pipe.zremrangeByRank(key,0,nowTs-period*10);
        Response<Long> count=pipe.zcard(key);
        pipe.expire(key,period+1);
        pipe.exec();
        pipe.close();
        return count.get()<=maxCount;
    }

    public static void main(String[] args) {
        Jedis jedis=new Jedis();
        SimpleRateLimiter limiter=new SimpleRateLimiter(jedis);
        for(int i=0;i<20;i++){
            System.out.println(limiter.isActionAllowed("laoqian","reply",60,5));
        }
    }
}