How to create non-blocking methods in Scala?

Question

What is a good way to create non-blocking methods in Scala? One way I can imagine is to create a thread / actor, and the method will just send a message to the stream and return. Is there a better way to create a non-blocking method?

Answer 1

Use scala.actors.Future:

import actors._

def asyncify[A, B](f: A => B): A => Future[B] = (a => Futures.future(f(a)))

// normally blocks when called
def sleepFor(seconds: Int) = {
  Thread.sleep(seconds * 1000)
  seconds
}

val asyncSleepFor = asyncify(sleepFor)
val future = asyncSleepFor(5) // now it does NOT block
println("waiting...")         // prints "waiting..." rightaway
println("future returns %d".format(future())) // prints "future returns 5" after 5 seconds

The overloaded "asyncify", which accepts a function with several parameters, remains as an exercise.

One caveat is exception handling. A function that is "asynchronized" should handle all exceptions, catching them. The behavior for exceptions excluded from the function is undefined.

Answer 2

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Answer 3

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Answer 4

I have a very detailed explanation on my futures blog. It actually shows you how you can implement futures yourself, and in this way you will get a very good understanding on this topic. I suggest you read it:

http://vigtig.it/blog/?p=73

Bring your coffee!