<?php
namespace GuzzleHttp\Ring\Future;

use React\Promise\PromiseInterface;
use React\Promise\PromisorInterface;

/**
* Represents the result of a computation that may not have completed yet.
*
* You can use the future in a blocking manner using the wait() function, or
* you can use a promise from the future to receive the result when the future
* has been resolved.
*
* When the future is dereferenced using wait(), the result of the computation
* is cached and returned for subsequent calls to wait(). If the result of the
* computation has not yet completed when wait() is called, the call to wait()
* will block until the future has completed.
*/
interface FutureInterface extends PromiseInterface, PromisorInterface
{
/**
* Returns the result of the future either from cache or by blocking until
* it is complete.
*
* This method must block until the future has a result or is cancelled.
* Throwing an exception in the wait() method will mark the future as
* realized and will throw the exception each time wait() is called.
* Throwing an instance of GuzzleHttp\Ring\CancelledException will mark
* the future as realized, will not throw immediately, but will throw the
* exception if the future's wait() method is called again.
*
* @return mixed
*/
public function wait();

/**
* Cancels the future, if possible.
*/
public function cancel();
}