How to block the thread and get Try[A] from Future[A]?-CodePudding

I have List[Future[A]]. I'd like to block my thread and get List[Try[A]] "right now". Can't find a nice solution.

CodePudding user response：

You can use Await: https://www.scala-lang.org/api/2.13.3/scala/concurrent/Await$.html

import scala.concurrent.Await
import scala.concurrent.duration._
import scala.util.Try

val res = Try(Await.result(someFuture, 10.seconds))

That said, blocking is rarely a good idea. Futures are meant to be composed with methods such as flatMap.

CodePudding user response：

Now that you have clarified your question (in the comment to my other answer), here's one possibility to do it:

import scala.util._
import scala.concurrent._

def partitionFutures[A](
  l: List[Future[A]])(
  implicit ec: ExecutionContext
): Future[(List[A], List[Throwable])] = {
  Future.traverse(l)(f => f.transform(Success.apply)).map { trys =>
    val as = trys.collect { case Success(a) => a }
    val errs = trys.collect { case Failure(err) => err }
    as -> errs
  }
}

The type isn't quite the same as the one you proposed, but it's unclear why you would want a list of pairs of lists, so I simplified it to a pair of lists.