Future[Try[A]] <=> Future[A] 상호간 변환하기

Future[Try[A]] <=> Future[A]  변환

 

Future[Try[A]] => Future[A]

import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future
import scala.util.{Success, Try}

object FutureTryTest {
  def main(args: Array[String]): Unit = {
    val futureTry: Future[Try[Int]] = Future(Success(1))
    
    // https://github.com/monix/monix/blob/series/3.x/monix-execution/shared/src/main/scala/monix/execution/FutureUtils.scala#L119-L120
    val future1: Future[Int] = futureTry.map(_.get)
    
    // https://github.com/scala-hamsters/hamsters/blob/3.1.0/shared/src/main/scala/io/github/hamsters/FutureOps.scala#L26-L28
    val future2: Future[Int] = futureTry.flatMap(Future.fromTry)
  }
}

그러나 이렇게 한다고 해서 Try[A] 의 evaluation 이 async 처리되는 것은 아니다. blocking 으로 똑 같이 처리되고, 다만 Future 로 감싸주는 역할만 할 뿐!

 

Future[A] => Future[Try[A]]

import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future
import scala.util.{Success, Try}

object FutureTryTest2 {
  def main(args: Array[String]): Unit = {
    val future: Future[Int] = Future.failed[Int](new Exception("some error"))

    // https://github.com/monix/monix/blob/series/3.x/monix-execution/shared/src/main/scala/monix/execution/FutureUtils.scala#L96-L98
    val futureTry: Future[Try[Int]] = future.transform(t => Success(t))
    println(futureTry) // Future(Success(Failure(java.lang.Exception: some error)))
  }
}