/// <reference types="node" />
import { ServerResponse } from 'http';
import { Cache, State } from './types';
export declare function hasLock(key: string, cache: Cache): Promise<boolean>;
export declare function lock(key: string, cache: Cache): Promise<void>;
export declare function unlock(key: string, cache: Cache): Promise<void>;
export declare function serveCache(cache: Cache, key: string, forced: boolean): Promise<State>;
export declare function send(payload: {
    body: Buffer | null;
    headers: Record<string, any> | null;
}, res: ServerResponse): void;