Is there a standard Scala function for running a block with a timeout?
With credit to the other answers - in the absence of any standard library function, I've gone down the Futures route.
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent._
import scala.concurrent.duration._
def runWithTimeout[T](timeoutMs: Long)(f: => T) : Option[T] = {
Some(Await.result(Future(f), timeoutMs milliseconds))
}
def runWithTimeout[T](timeoutMs: Long, default: T)(f: => T) : T = {
runWithTimeout(timeoutMs)(f).getOrElse(default)
}
So that
@Test def test {
runWithTimeout(50) { "result" } should equal (Some("result"))
runWithTimeout(50) { Thread.sleep(100); "result" } should equal (None)
runWithTimeout(50, "no result") { "result" } should equal ("result")
runWithTimeout(50, "no result") { Thread.sleep(100); "result" } should equal("no result")
}
I'd be grateful for any feedback as to whether this is a good Scala style!
Might Futures and its alarm
do the trick?
You could use a future
import scala.actors.Futures._
val myfuture =
future {
Thread.sleep(5000)
println("<future>")
"future "
}
awaitAll(300,myfuture ) foreach println _
But also have a look at Circuit Breaker for Scala which is a implementation of the Circuit Breaker Pattern. Basically it lets you control the timeout and what should happen if a failure occurs accessing an external resource
Usage looks like this in Scala (from the readme) :
. . .
addCircuitBreaker("test", CircuitBreakerConfiguration(timeout=100,failureThreshold=10))
. . .
class Test extends UsingCircuitBreaker {
def myMethodWorkingFine = {
withCircuitBreaker("test") {
. . .
}
}
def myMethodDoingWrong = {
withCircuitBreaker("test") {
require(false,"FUBAR!!!")
}
}
}