MpscChunkedMailbox.java

import akka.actor.ActorRef;
import akka.dispatch.Envelope;
import akka.dispatch.MessageQueue;
import akka.dispatch.UnboundedMessageQueueSemantics;
import org.jctools.queues.MpscChunkedArrayQueue;
import org.jctools.util.Pow2;

public final class MpscChunkedMailbox implements MessageQueue, UnboundedMessageQueueSemantics {

  private final MpscChunkedArrayQueue<Envelope> queue;

  public MpscChunkedMailbox(int chunkSize) {
    queue = new MpscChunkedArrayQueue<>(chunkSize, Pow2.MAX_POW2, true);
  }

  @Override
  public void enqueue(ActorRef receiver, Envelope handle) {
    queue.offer(handle);
  }

  @Override
  public Envelope dequeue() {
    return queue.poll();
  }

  @Override
  public int numberOfMessages() {
    return queue.size();
  }

  @Override
  public boolean hasMessages() {
    return !queue.isEmpty();
  }

  @Override
  public void cleanUp(ActorRef owner, MessageQueue deadLetters) {
    if (hasMessages()) {
      Envelope envelope;
      while ((envelope = queue.poll()) != null) {
        deadLetters.enqueue(owner, envelope);
      }
    }
  }
}

MpscChunkedMailboxType.java

import akka.actor.ActorRef;
import akka.actor.ActorSystem;
import akka.dispatch.MailboxType;
import akka.dispatch.MessageQueue;
import akka.dispatch.ProducesMessageQueue;
import com.typesafe.config.Config;
import scala.Option;

public final class MpscChunkedMailboxType implements MailboxType, ProducesMessageQueue<MpscChunkedMailbox> {

  private final int chunkSize;

  @SuppressWarnings("UnusedParameters")
  public MpscChunkedMailboxType(ActorSystem.Settings settings, Config config) {
    chunkSize = config.getInt("chunk-size");
    if (chunkSize < 1) {
      throw new IllegalArgumentException("Mailbox chunk size must not be less than 1");
    }
  }

  @Override
  public MessageQueue create(Option<ActorRef> owner, Option<ActorSystem> system) {
    return new MpscChunkedMailbox(chunkSize);
  }
}

references.conf

chunked-mailbox-8 {
  mailbox-type = "mailbox.MpscChunkedMailboxType"
  chunk-size = 8
}

chunked-mailbox-16 {
  mailbox-type = "mailbox.MpscChunkedMailboxType"
  chunk-size = 16
}

chunked-mailbox-128 {
  mailbox-type = "mailbox.MpscChunkedMailboxType"
  chunk-size = 128
}

chunked-mailbox-1024 {
  mailbox-type = "mailbox.MpscChunkedMailboxType"
  chunk-size = 1024
}