There is a contrib implementation of message Throttling, as described here.
The code is very simple:
// A simple actor that prints whatever it receives
class Printer extends Actor {
def receive = {
case x => println(x)
}
}
val printer = system.actorOf(Props[Printer], "printer")
// The throttler for this example, setting the rate
val throttler = system.actorOf(Props(classOf[TimerBasedThrottler], 3 msgsPer 1.second))
// Set the target
throttler ! SetTarget(Some(printer))
// These three messages will be sent to the printer immediately
throttler ! "1"
throttler ! "2"
throttler ! "3"
// These two will wait at least until 1 second has passed
throttler ! "4"
throttler ! "5"