raboof/pekko
1
0
Fork 0
Code Issues Pull requests Projects Releases 6 Packages Wiki Activity Actions 10

add more explanation for NullMessage

Browse source
This commit is contained in:
Roland 2012-08-21 14:10:37 +02:00
parent f0c370cf87
commit 6ce38537d1
1 changed files with 8 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

8
akka-actor/src/main/scala/akka/dispatch/AbstractDispatcher.scala
View file

@ -41,6 +41,14 @@ object Envelope {
* This message is sent directly after the Supervise system message in order * 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. * 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. * 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.
*/ */
case object NullMessage extends AutoReceivedMessage case object NullMessage extends AutoReceivedMessage