/**
 * Cache layer: optional LRU in front of storage. Invalidates on write.
 */
/** Cached value per data type; collection maps are keyed by the latin1 form of the field or member. */
export interface CacheValues {
    string: Buffer;
    hash: Map<string, [Buffer, Buffer]>;
    set: Map<string, Buffer>;
    list: Buffer[];
    zset: Map<string, [Buffer, string, number]>;
}
export type CacheKind = keyof CacheValues;
export type CacheEntry = {
    [K in CacheKind]: {
        kind: K;
        version: number;
        expiresAt: number | bigint | null;
        value: CacheValues[K];
    };
}[CacheKind];
export interface CacheOptions {
    enabled?: boolean;
    maxEntries?: number;
    maxBytes?: number;
    maxHashFields?: number;
    maxHashBytes?: number;
    maxSetMembers?: number;
    maxSetBytes?: number;
    maxListItems?: number;
    maxListBytes?: number;
    maxZsetMembers?: number;
    maxZsetBytes?: number;
}
export declare function createCache(opts?: CacheOptions): {
    get(key: string): CacheEntry | null;
    set<K extends CacheKind>(key: string, kind: K, value: CacheValues[K], version: number, expiresAt: number | bigint | null): void;
    invalidate(key: string): void;
    clear(): void;
    limits: Readonly<{
        maxHashFields: number;
        maxHashBytes: number;
        maxSetMembers: number;
        maxSetBytes: number;
        maxListItems: number;
        maxListBytes: number;
        maxZsetMembers: number;
        maxZsetBytes: number;
    }>;
    readonly stats: {
        entries: number;
        bytes: number;
        hits: number;
        misses: number;
        hitRatio: number;
        enabled: boolean;
    };
};
export type Cache = ReturnType<typeof createCache>;