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I have some functions which return Futures. The callers register callbacks by onComplete. 

def makeHttpRequest(): Future[T] = ??? makeHttpRequest().onComplete { case Success(v) => ??? case Failure(ex) => ??? }

Now I want to enable retries on these functions (or function callings). Is there any suggestion on how to achieve this?

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There is no retry capability out-of-the-box. However based on Retry a function that returns a Future consider

def retry[T](n: Int, expr: => Future[T]): Future[T] = Future.unit.flatMap(_ => expr).recoverWith { case e if n > 1 => retry(n - 1, expr) case e => Future.failed(e) } retry(3, makeHttpRequest())

https://scalafiddle.io/sf/otseSX0/0

or consider dedicated library such as softwaremill/retry.

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2 Comments

in first case clausure you need to have case e if n > 1 not case e if n > 0 to retry 3 times instead of 4.
What if we want to wait for a while to make another attempt? sleep is not a great choice. Is there any other simple option? I'm using Akka/Scala, but don't want to reschedule the message to the actor.
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def makeHttpRequest(maxRetryCount: Int, currentRetryCount: Int = 0): Future[T] = { val responseFuture = ??? if (currentRetryCount == maxRetryCount) responseFuture else responseFuture.recoverWith(makeHttpRequest(maxRetryCount, currentRetryCount + 1)) } makeHttpRequest(3).onComplete { case Success(v) => ??? case Failure(ex) => ??? }
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