Trait for exposing metrics for akka-actors.

ActorMetrics.scala

import akka.actor.Actor
import com.yammer.metrics.Instrumented

// Useful for monitoring the mailbox size of actors.
// Just fire up your favorite JMX client and watch the pretty graph (which hopefully is a flatline at 0).
trait ActorMetrics extends Instrumented { actor: Actor =>
  metrics.gauge("mailbox size", self.id){actor.self.dispatcher.mailboxSize(actor.self)}
}