/**
 * CacheService - In-memory caching with TTL support
 *
 * Features:
 * - TTL (Time To Live) support
 * - Automatic cleanup of expired entries
 * - Type-safe cache operations
 * - Cache statistics
 */
interface CacheStats {
    hits: number;
    misses: number;
    size: number;
    hitRate: number;
}
export declare class CacheService {
    private static instance;
    private cache;
    private logger;
    private stats;
    private cleanupInterval;
    private readonly defaultTTL;
    private constructor();
    static getInstance(): CacheService;
    /**
     * Get value from cache
     */
    get<T>(key: string): T | null;
    /**
     * Set value in cache with optional TTL
     */
    set<T>(key: string, value: T, ttlMs?: number): void;
    /**
     * Check if key exists and is not expired
     */
    has(key: string): boolean;
    /**
     * Delete value from cache
     */
    delete(key: string): boolean;
    /**
     * Clear all cache entries
     */
    clear(): void;
    /**
     * Get or set pattern - fetch if not in cache
     */
    getOrSet<T>(key: string, fetcher: () => Promise<T>, ttlMs?: number): Promise<T>;
    /**
     * Get cache statistics
     */
    getStats(): CacheStats;
    /**
     * Start automatic cleanup of expired entries
     */
    private startCleanup;
    /**
     * Clean up expired entries
     */
    private cleanup;
    /**
     * Stop cleanup interval (for testing/shutdown)
     */
    stopCleanup(): void;
}
export {};
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