Akka Actor how to only process the latest message

Question

Say I am sending messages to an Actor, when it is processing one message several more messages may arise. Now when it is ready to process the next message I want it to only

Answer 1

There is no need to implement your own mailbox. At all.

Removed a lot of text and let this piece of code speak for itself:

// Either implement "equals" so that every job is unique (by default) or do another comparison in the match.
class Work 
case class DoWork(work: Work)

class WorkerActor extends Actor {
  // Left as an exercise for the reader, it clearly should do some work.
  def perform(work: Work): Unit = ()

  def lookingForWork: Receive = {
    case w: Work =>
      self forward DoWork(w)
      context become prepareToDoWork(w)
  }

  def prepareToDoWork(work: Work): Receive = {
    case DoWork(`work`) =>
      // No new work, so perform this one
      perform(work)
      // Now we're ready to look for new work
      context become lookingForWork
    case DoWork(_) =>
      // Discard work that we don't need to do anymore
    case w2: Work =>
      // Prepare to do this newer work instead
      context become prepareToDoWork(w2) 
  }

  //We start out as looking for work
  def receive = lookingForWork
}

This means that work will only be performed if there is no newer work in the mailbox.