JarCastingStateless Future For Akka
stateless-future-akka allows you to build control flow for Akka actor in the native Scala syntax. stateless-future-akka bases on stateless-future, which is a better future system than scala.concurrent.Future.
Usage
Step 1: Mix-in FutureFactory with your Actor
import com.qifun.statelessFuture.akka.FutureFactory
import akka.actor._
class YourActor extends Actor with FutureFactory {
}
Step 2: Implement the receive method from a Future block
import com.qifun.statelessFuture.akka.FutureFactory
import akka.actor._
class YourActor extends Actor with FutureFactory {
override def receive = Future {
???
}
}
Step 3: Receive and send message in the Future block
There is a magic method nextMessage.await that receive the next message from the actor's mail box. Unlike a normal Actor.Receive, You are able to receive multiple message sequentially in a Future block:
import com.qifun.statelessFuture.akka.FutureFactory
import akka.actor._
class YourActor extends Actor with FutureFactory {
override def receive = Future {
while (true) {
val message1 = nextMessage.await
val message2 = nextMessage.await
sender ! s"You have sent me $message1 and $message2"
}
throw new IllegalStateException("Unreachable code!")
}
}
Note that the Future block for receive must receive all the message until the actor stops. In fact, the def receive = Future { ??? } is a shortcut of def receive = FutureFactory.receiveForever(Future[Nothing] { ??? }).
Another example
This example creates an actor that concatenates arbitrary number of strings.
import com.qifun.statelessFuture.akka.FutureFactory
import akka.actor._
import scala.concurrent.duration._
class ConcatenationActor extends Actor with FutureFactory {
def nextInt: Future[Int] = Future {
nextMessage.await.toString.toInt
}
override def receive = Future {
while (true) {
// Should behave the same as:
// val numberOfSubstrings = nextMessage.await.toString.toInt
val numberOfSubstrings = nextInt.await
var i = 0
val sb = new StringBuilder
while (i < numberOfSubstrings) {
sb ++= nextMessage.await.toString
i += 1
}
val result = sb.toString
println(result)
sender ! result
}
throw new IllegalStateException("Unreachable code!")
}
}
object ConcatenationActor {
def main(arguments: Array[String]) {
val system = ActorSystem("helloworld")
val concatenationActor = system.actorOf(Props[ConcatenationActor], "concatenationActor")
val inbox = Inbox.create(system)
inbox.send(concatenationActor, "4")
inbox.send(concatenationActor, "Hello")
inbox.send(concatenationActor, ", ")
inbox.send(concatenationActor, "world")
inbox.send(concatenationActor, "!")
assert(inbox.receive(5.seconds) == "Hello, world!")
inbox.send(concatenationActor, "2")
inbox.send(concatenationActor, "Hello, ")
inbox.send(concatenationActor, "world, again!")
assert(inbox.receive(5.seconds) == "Hello, world, again!")
}
}
Installation
Put these lines in your build.sbt if you use Sbt:
libraryDependencies += "com.qifun" %% "stateless-future-akka" % "0.1.1"
stateless-future-akka should work with Scala 2.10.3, 2.10.4, or 2.11.0.