akka.dispatch
Class NullMessage

java.lang.Object
  akka.dispatch.NullMessage

All Implemented Interfaces:

java.io.Serializable, scala.Equals, scala.Product

public class NullMessage
extends java.lang.Object
implements scala.Product, scala.Serializable

This message is sent directly after the Supervise system message in order to form a barrier wrt. the first real message sent by the child, so that e.g. Failed() cannot overtake Supervise(). Processing this does nothing.

Detailed explanation:

The race happens because Supervise and Failed may be queued between the parent's check for system messages and dequeue(). Thus, if the parent processes the NullMessage first (by way of that tiny race window), it is guaranteed to then find the Supervise system message in its mailbox prior to turning its attention to the next real message.

See Also:

Serialized Form

Constructor Summary

NullMessage()

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface scala.Product

productArity, productElement, productIterator, productPrefix

Methods inherited from interface scala.Equals

canEqual, equals

Constructor Detail

NullMessage

public NullMessage()