import { ICacheMetricsRecorder } from '../ICacheMetricsRecorder';
import { ICacheStats } from '../ICacheStats';
import { ILayeredCache } from '../interfaces/ILayeredCache';
/**
 * Configuration options for {@link MemoryLayeredCache}.
 *
 * @public
 */
export interface ILayeredCacheOptions {
    /**
     * Time to live in milliseconds. Entries older than this are considered expired.
     * Defaults to infinite (no expiration).
     *
     * @public
     */
    ttlMs?: number;
    /**
     * When `true`, expired entries are served immediately while a background
     * refresh is triggered. Defaults to `false`.
     *
     * @public
     */
    staleWhileRevalidate?: boolean;
    /**
     * Maximum number of entries retained in the cache. Oldest entries are
     * evicted first (LRU). Defaults to infinite.
     *
     * @public
     */
    maxEntries?: number;
    /**
     * Optional metrics recorder forwarded cache operation statistics.
     * Falls back to {@link NoopCacheMetricsRecorder} when omitted.
     *
     * @public
     */
    metricsRecorder?: ICacheMetricsRecorder;
    /**
     * An optional name / label for the cache instance, used in metrics.
     * Defaults to `'memory'`.
     *
     * @public
     */
    cacheName?: string;
}
/**
 * In-memory layered cache with LRU eviction, TTL expiration and
 * optional stale-while-revalidate support. Falls back to an
 * asynchronous loader function on cache misses.
 *
 * @public
 * @template TKey  The type of the cache keys.
 * @template TValue  The type of the cache values.
 */
export declare class MemoryLayeredCache<TKey, TValue> implements ILayeredCache<TKey, TValue> {
    private readonly _store;
    private readonly _logger;
    private readonly _loadFn;
    private readonly _options;
    private readonly _metrics;
    private readonly _cacheName;
    private _hits;
    private _misses;
    private _loads;
    private _loadErrors;
    private _evictions;
    /**
     * Initializes a new instance of the {@link MemoryLayeredCache} class.
     *
     * @param loadFn - Async loader invoked on cache misses.
     * @param options - Optional configuration for TTL, LRU and metrics.
     */
    constructor(loadFn: (key: TKey) => Promise<TValue | undefined>, options?: ILayeredCacheOptions);
    /** @inheritdoc */
    get(key: TKey): TValue | undefined;
    /** @inheritdoc */
    getAsync(key: TKey): Promise<TValue | undefined>;
    /** @inheritdoc */
    set(key: TKey, value: TValue): void;
    /** @inheritdoc */
    setAsync(key: TKey, value: TValue): Promise<void>;
    /** @inheritdoc */
    warm(key: TKey): Promise<TValue | undefined>;
    /** @inheritdoc */
    invalidate(key: TKey): void;
    /** @inheritdoc */
    invalidateAsync(key: TKey): Promise<void>;
    /** @inheritdoc */
    stats(): ICacheStats;
    private _isExpired;
    private _loadFresh;
    private _refresh;
    private _touch;
    private _insert;
    private _enforceMax;
}