interface CacheEntry {
    data: any;
    etag: string;
    timestamp: number;
}
export declare class ETagCacheService {
    private readonly logger;
    private cache;
    private defaultTtl;
    private safeStringify;
    computeETag(data: any): string | null;
    get(key: string, ttl?: number): CacheEntry | null;
    set(key: string, data: any): string | null;
    invalidate(key: string): void;
    invalidatePattern(pattern: string): void;
    clear(): void;
}
export {};
