/**
 * QueryCache - LRU Query Cache for AgentDB
 *
 * Provides 20-40% speedup on repeated queries through intelligent caching.
 * Features:
 * - LRU (Least Recently Used) eviction policy
 * - TTL (Time To Live) support for cache entries
 * - Thread-safe operations
 * - Automatic cache invalidation on writes
 * - Hit/miss ratio tracking
 * - Memory-efficient (size-based limits)
 */
export interface QueryCacheConfig {
    /** Maximum number of cache entries (default: 1000) */
    maxSize?: number;
    /** Default TTL in milliseconds (default: 5 minutes = 300000ms) */
    defaultTTL?: number;
    /** Enable cache (default: true) */
    enabled?: boolean;
    /** Maximum size in bytes for cached results (default: 10MB) */
    maxResultSize?: number;
}
export interface CacheEntry<T = any> {
    /** Cached value */
    value: T;
    /** Cache key */
    key: string;
    /** Timestamp when entry was created */
    timestamp: number;
    /** TTL for this entry in milliseconds */
    ttl: number;
    /** Estimated size in bytes */
    size: number;
    /** Number of times this entry was accessed */
    hits: number;
}
export interface CacheStatistics {
    /** Total cache hits */
    hits: number;
    /** Total cache misses */
    misses: number;
    /** Hit rate percentage (0-100) */
    hitRate: number;
    /** Current cache size */
    size: number;
    /** Maximum cache capacity */
    capacity: number;
    /** Number of evictions */
    evictions: number;
    /** Total memory used (estimated bytes) */
    memoryUsed: number;
    /** Cache entries by category */
    entriesByCategory: Record<string, number>;
}
export declare class QueryCache {
    private config;
    private cache;
    private accessOrder;
    private stats;
    constructor(config?: QueryCacheConfig);
    /**
     * Generate cache key from SQL query and parameters
     */
    generateKey(sql: string, params?: any[], category?: string): string;
    /**
     * Get value from cache
     */
    get<T = any>(key: string): T | undefined;
    /**
     * Set value in cache
     */
    set<T = any>(key: string, value: T, ttl?: number): void;
    /**
     * Check if key exists in cache (without updating access time)
     */
    has(key: string): boolean;
    /**
     * Delete specific key from cache
     */
    delete(key: string): boolean;
    /**
     * Invalidate cache entries by category (e.g., 'episodes', 'skills')
     */
    invalidateCategory(category: string): number;
    /**
     * Clear all cache entries
     */
    clear(): void;
    /**
     * Get cache statistics
     */
    getStatistics(): CacheStatistics;
    /**
     * Reset statistics (but keep cache entries)
     */
    resetStatistics(): void;
    /**
     * Prune expired entries
     */
    pruneExpired(): number;
    /**
     * Warm cache with common queries
     */
    warm(warmupFn: (cache: QueryCache) => Promise<void>): Promise<void>;
    /**
     * Enable or disable caching
     */
    setEnabled(enabled: boolean): void;
    /**
     * Get current configuration
     */
    getConfig(): Readonly<Required<QueryCacheConfig>>;
    /**
     * Update configuration (note: doesn't clear cache)
     */
    updateConfig(config: Partial<QueryCacheConfig>): void;
    /**
     * Evict least recently used entry
     */
    private evictLRU;
    /**
     * Update access order for LRU tracking
     */
    private updateAccessOrder;
    /**
     * Remove key from access order
     */
    private removeFromAccessOrder;
    /**
     * Simple string hash function for key generation
     */
    private hashCode;
    /**
     * Estimate size of cached value in bytes
     */
    private estimateSize;
}
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