public class RateLimit {
    private long bucketSize;
    private double currentNum;
    private double rate;
    // 最后一次加水时间
    private long lastTime;
    private Lock lock;

    public static RateLimit create(long ticketPerSecond) {
        RateLimit rateLimit = new RateLimit();
        rateLimit.bucketSize = ticketPerSecond;
        rateLimit.currentNum = 0;
        rateLimit.rate = ticketPerSecond;
        rateLimit.lastTime = System.currentTimeMillis();
        rateLimit.lock = new ReentrantLock();

        return rateLimit;
    }

    public boolean tryAcquire() {
        try {
            lock.lock();
            long curTime = System.currentTimeMillis();
            this.currentNum = Math.max(0, currentNum - (curTime - lastTime) * rate / 1000);
            lastTime = curTime;

            if (bucketSize - currentNum >= 1) {
                currentNum++;
                return true;
            } else {
                return false;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }

        return false;
    }

    public static void main(String[] args) {
        final RateLimit rateLimit = create(5);

        while (true) {
            System.out.println(rateLimit.tryAcquire() + " - " + Thread.currentThread().getId() + " - " + System.currentTimeMillis() + " - " + rateLimit.currentNum);
            try {
                Thread.sleep(10);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}