/**
 * @file src/semaphore/index.ts
 * @copyright 2018-present Karim Alibhai. All rights reserved.
 */
import { SemaphoreOptions } from './types';
import { Lock, ReleaseLock } from '../types';
export declare class Semaphore extends Lock {
    readonly size: number;
    private readonly mutex;
    private readonly state;
    constructor(options: SemaphoreOptions);
    /**
     * Tries to obtain a token from the semaphore.
     * @param {boolean = true} failWithoutLock if true, it will throw an error if it cannot obtain a token
     * @returns {Promise<ReleaseLock>} resolves with a function that can be used to release the token
     */
    lock(failWithoutLock?: boolean): Promise<ReleaseLock>;
}