import java.util.concurrent.atomic.AtomicLong;

public class RateLimiter {
    private final long capacity;  // 令牌桶容量
    private final double rate;  // 令牌生成速率
    private AtomicLong tokens;  // 当前令牌数量
    private long lastRefillTime;  // 上次令牌生成时间

    public RateLimiter(long capacity, double rate) {
        this.capacity = capacity;
        this.rate = rate;
        this.tokens = new AtomicLong(capacity);
        this.lastRefillTime = System.currentTimeMillis();
    }

    private void refillTokens() {
        long now = System.currentTimeMillis();
        long timePassed = now - lastRefillTime;
        long tokensToAdd = (long) (timePassed * rate / 1000);
        tokens.set(Math.min(capacity, tokens.get() + tokensToAdd));
        lastRefillTime = now;
    }

    public boolean allowRequest() {
        refillTokens();
        if (tokens.get() >= 1) {
            tokens.decrementAndGet();
            return true;
        } else {
            return false;
        }
    }
}