/**
 * 滑动窗口速率限制器 — 使用环形缓冲区，O(1) 摊销复杂度
 */
export declare class RollingWindowRateLimiter {
    private readonly windowMs;
    private readonly maxRequests;
    private readonly burstLimit;
    /** 环形缓冲区存储时间戳 */
    private ring;
    /** 写入指针 */
    private head;
    /** 有效元素数量 */
    private count;
    constructor(windowMs?: number, maxRequests?: number, burstLimit?: number);
    tryAcquire(): boolean;
    stats(): {
        windowCount: number;
        windowMs: number;
        maxRequests: number;
    };
    destroy(): void;
    /** 从尾部驱逐过期条目 */
    private evictExpired;
    /** 统计最近 1s 内的请求数 */
    private burstCount;
}
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