import * as mongodb from "mongodb";
import { BasicCache } from "./BasicCache";
export declare class MongoCache extends BasicCache {
    private initPromise;
    private db;
    constructor(url: string, opts?: mongodb.MongoClientOptions);
    private initCollection;
    exists(key: string): Promise<boolean>;
    get(key: string): Promise<any>;
    set(key: string, value: any, ttl: number): Promise<void>;
    delete(key: string): Promise<void>;
    deleteAll(): Promise<void>;
}