/**
 * db4ai Query Cache
 *
 * Provides caching strategies for repeated queries with TTL,
 * LRU eviction, and cache invalidation support.
 *
 * @packageDocumentation
 */
/**
 * Cache configuration options.
 */
export interface CacheConfig {
    /** Maximum number of entries (default: 1000) */
    maxEntries?: number;
    /** Maximum cache size in bytes (default: 50MB) */
    maxSize?: number;
    /** Default TTL in milliseconds (default: 60000) */
    defaultTtl?: number;
    /** Eviction policy (default: 'lru') */
    evictionPolicy?: 'lru' | 'lfu' | 'fifo';
    /** Enable cache statistics (default: true) */
    enableStats?: boolean;
    /** Stale-while-revalidate window in ms (default: 0, disabled) */
    staleWhileRevalidate?: number;
}
/**
 * Cache statistics.
 */
export interface CacheStats {
    /** Total number of hits */
    hits: number;
    /** Total number of misses */
    misses: number;
    /** Hit ratio (0-1) */
    hitRatio: number;
    /** Current number of entries */
    entries: number;
    /** Current size in bytes */
    size: number;
    /** Number of evictions */
    evictions: number;
    /** Number of expirations */
    expirations: number;
}
/**
 * Cache get options.
 */
export interface CacheGetOptions {
    /** Allow returning stale data while revalidating */
    allowStale?: boolean;
}
/**
 * Cache set options.
 */
export interface CacheSetOptions {
    /** Custom TTL for this entry */
    ttl?: number;
    /** Tags for cache invalidation */
    tags?: string[];
}
/**
 * High-performance LRU cache with TTL support.
 *
 * Features:
 * - O(1) get/set operations using Map
 * - LRU/LFU/FIFO eviction policies
 * - Size-based eviction
 * - TTL with stale-while-revalidate support
 * - Tag-based cache invalidation
 * - Detailed statistics
 */
export declare class QueryCache<T = unknown> {
    private readonly config;
    private readonly cache;
    private readonly tagIndex;
    private currentSize;
    private cleanupTimer;
    private hits;
    private misses;
    private evictions;
    private expirations;
    constructor(config?: CacheConfig);
    /**
     * Get a value from the cache.
     */
    get(key: string, options?: CacheGetOptions): T | undefined;
    /**
     * Check if a key exists and is not expired.
     */
    has(key: string): boolean;
    /**
     * Set a value in the cache.
     */
    set(key: string, value: T, options?: CacheSetOptions): void;
    /**
     * Delete a specific entry.
     */
    delete(key: string): boolean;
    /**
     * Invalidate all entries with a specific tag.
     */
    invalidateByTag(tag: string): number;
    /**
     * Invalidate entries matching a pattern.
     */
    invalidateByPattern(pattern: RegExp): number;
    /**
     * Clear all entries.
     */
    clear(): void;
    /**
     * Get cache statistics.
     */
    getStats(): CacheStats;
    /**
     * Reset statistics.
     */
    resetStats(): void;
    /**
     * Get the current size in bytes.
     */
    get size(): number;
    /**
     * Get the number of entries.
     */
    get entries(): number;
    /**
     * Shutdown the cache.
     */
    shutdown(): void;
    /**
     * Get or set a value (cache-aside pattern).
     */
    getOrSet(key: string, factory: () => Promise<T>, options?: CacheSetOptions): Promise<T>;
    private estimateSize;
    private evictIfNeeded;
    private evictOne;
    private evictExpired;
}
/**
 * Generate a cache key from query parameters.
 */
export declare function generateCacheKey(collection: string, operation: string, params?: unknown): string;
/**
 * Create a new query cache.
 */
export declare function createQueryCache<T = unknown>(config?: CacheConfig): QueryCache<T>;
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