令牌桶算法實現API限流

令牌桶算法( Token Bucket )和 Leaky Bucket 效果一樣但方向相反的算法,更加容易理解.隨着時間流逝,系統會按恆定 1/QPS 時間間隔(如果 QPS=100 ,則間隔是 10ms )往桶里加入 Token(想象和漏洞漏水相反,有個水龍頭在不斷的加水),如果桶已經滿了就不再加了.新請求來臨時,會各自拿走一個 Token ,如果沒有 Token 可拿了就阻塞或者拒絕服務.

 

 @Autowired
    private JedisClientService jedisClient;

    public boolean acquire(String key, Integer permits, long currMillSecond) {
        try  {

            //針對新用戶創建令牌桶
            if (!jedisClient.exists(key)) {
                jedisClient.hset(key, "last_mill_second", String.valueOf(currMillSecond));
                jedisClient.hset(key, "curr_permits", "0");
                jedisClient.hset(key, "max_permits", "50");
                jedisClient.hset(key, "rate", "400");
                return true;
            }
            //獲取令牌桶信息，上一個令牌時間，當前可用令牌數，最大令牌數，令牌消耗速率
            List<String> limitInfo = jedisClient.hmget(key, "last_mill_second", "curr_permits", "max_permits", "rate");
            long lastMillSecond = Long.parseLong(limitInfo.get(0));
            Integer currPermits = Integer.valueOf(limitInfo.get(1));
            Integer maxPermits = Integer.valueOf(limitInfo.get(2));
            Double rate = Double.valueOf(limitInfo.get(3));
            //向桶里面添加令牌
            Double reversePermitsDouble = ((currMillSecond - lastMillSecond) / 1000) * rate;

            Integer reversePermits = reversePermitsDouble.intValue();
            Integer expectCurrPermits = reversePermits + currPermits;
            Integer localCurrPermits = Math.min(expectCurrPermits, maxPermits);
            //添加令牌之后更新時間
            if (reversePermits > 0) {
                jedisClient.hset(key, "last_mill_second", String.valueOf(currMillSecond));
            }
            //判斷桶里面剩余的令牌數目
            if (localCurrPermits - permits >= 0) {
                jedisClient.hset(key, "curr_permits", String.valueOf(localCurrPermits - permits));
                return true;
            } else {
                jedisClient.hset(key, "curr_permits", String.valueOf(localCurrPermits));
                return false;
            }
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

　　

 

參考文章: https://blog.csdn.net/tianyaleixiaowu/article/details/74942405