Actors.md

Actor support

A number of Stackable Traits are available to quickly instrument Pekko or Akka actors. In all cases, the actual actor implementation must be mixed in prior to these stackable traits.

Usage follows a common pattern (the DefaultInstrumented trait is described earlier in the documentation):

trait MyActor extends Actor with DefaultInstrumented {
  def receive = {
    case "foo" => sender() ! "bar"
    case "bar" =>
        sender() ! "baz"
        context.stop(self)
  }
}

class MyActorInstrumented extends MyActor with
                          with ActorInstrumentedLifeCycle
                          with ReceiveCounterActor with ReceiveTimerActor with ReceiveExceptionMeterActor

Life cycle support for gauges: ActorInstrumentedLifeCycle

Getting the IllegalArgumentException "A metric named some-gauge already exists"?

When an actor is restarted, gauges can not be created again under the same name in the same metric registry. By mixing in the ActorInstrumentedLifeCycle trait, all gauges created in this actor will be automatically unregistered before this actor restarts.

Receive counter: ReceiveCounterActor

This trait provides a counter of messages received by the actor. This count will only increment if the message matches the receive partial function.

Receive timer: ReceiveTimerActor

This trait provides a timer of the execution of the receive partial function. Because it's a timer, you get a call meter and call counter for free. This is part of the dropwizard metrics library.

Receive exception meter: ReceiveExceptionMeterActor

This trait provides an exception meter around the receive partial function. This does not differentiate exceptions by Supervisor configuration. Any exception thrown by receive will be counted equally, ignoring whether the Supervisor chooses to restart, escalate, or other.

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