Update state in actor from within a future - scala

Question

Consider the following code sample:
class MyActor (httpClient: HttpClient) {
var canSendMore = true
override def receive: Receive = {
case PayloadA(name: String) => send(urlA)
case PayloadB(name: String) => send(urlB)
def send(url: String){
if (canSendMore)
httpClient.post(url).map(response => canSendMore = response.canSendMore)
else {
Thread.sleep(5000) //this will be done in a more elegant way, it's just for the example.
httpClient.post(url).map(response => canSendMore = response.canSendMore)
}
}
}
Each message handling will result in an async http request. (post return value is a Future[Response])
My problem is that I want to safely update counter ( At the moment there is a race condition)
BTW, I must somehow update counter in the same thread, or at least before any other message is processed by this actor.
Is this possible?

Answer 1

You can use become + stash combination to keep on stashing messages when the http request future is in process.
object FreeToProcess
case PayloadA(name: String)
class MyActor (httpClient: HttpClient) extends Actor with Stash {
def canProcessReceive: Receive = {
case PayloadA(name: String) => {
// become an actor which just stashes messages
context.become(canNotProcessReceive, discardOld = false)
httpClient.post(urlA).onComplete({
case Success(x) => {
// Use your result
self ! FreeToProcess
}
case Failure(e) => {
// Use your failure
self ! FreeToProcess
}
})
}
}
def canNotProcessReceive: Receive = {
case CanProcess => {
// replay stash to mailbox
unstashAll()
// start processing messages
context.unbecome()
}
case msg => {
stash()
}
}
}