/**
 * Generic TTL-based LRU cache with configurable size and expiration.
 * Provides a reusable caching utility for embeddings, metadata, and other data.
 */
export interface CacheOptions {
    /** Maximum number of entries (default: 100) */
    maxSize?: number;
    /** Time-to-live in milliseconds (default: 1 hour) */
    ttlMs?: number;
}
/**
 * A generic LRU cache with TTL-based expiration.
 *
 * Features:
 * - Configurable max size with LRU eviction
 * - TTL-based expiration for entries
 * - Automatic cleanup of expired entries on access
 * - Thread-safe for single-threaded Node.js
 *
 * @example
 * ```typescript
 * const cache = new TTLCache<number[]>({ maxSize: 50, ttlMs: 30000 });
 * cache.set('key', [1, 2, 3]);
 * const value = cache.get('key'); // [1, 2, 3] or undefined if expired
 * ```
 */
export declare class TTLCache<T> {
    private cache;
    private readonly maxSize;
    private readonly ttlMs;
    constructor(options?: CacheOptions);
    /**
     * Get a value from the cache.
     * Returns undefined if not found or expired.
     * Updates access time for LRU tracking.
     */
    get(key: string): T | undefined;
    /**
     * Set a value in the cache.
     * Evicts expired entries and oldest entry if at capacity.
     */
    set(key: string, value: T): void;
    /**
     * Check if a key exists and is not expired.
     */
    has(key: string): boolean;
    /**
     * Delete a specific key from the cache.
     */
    delete(key: string): boolean;
    /**
     * Clear all entries from the cache.
     */
    clear(): void;
    /**
     * Get the current number of entries (including potentially expired ones).
     */
    get size(): number;
    /**
     * Get cache statistics.
     */
    getStats(): {
        size: number;
        maxSize: number;
        ttlMs: number;
    };
    /**
     * Evict all expired entries.
     */
    private evictExpired;
    /**
     * Force cleanup of all expired entries.
     * Useful for periodic maintenance.
     */
    cleanup(): number;
}
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