import { CacheStrategy, CacheOptions } from './cacheStrategy';
export declare class ExternalCache extends CacheStrategy {
    private baseUrl;
    private options;
    constructor(options: CacheOptions);
    set(key: string, value: Buffer): Promise<void>;
    get(key: string): Promise<Buffer | null>;
    preload(key: string): Promise<void>;
    clear(): Promise<void>;
    private getNextChunkKey;
}