[jboss-jira] [JBoss JIRA] (JGRP-1579) NAKACK2 / UNICAST2: last message sent to self may not get delivered

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1579?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12751966#comment-12751966 ] 

Bela Ban commented on JGRP-1579:
--------------------------------

Actually, on second thought, this is not an issue, as *a message from A will always be received by A !* The problem occurred because we placed DISCARD just below NAKACK2; however, this is *not* the place where messages are dropped (or else this would constitute a bug !). Messages are dropped by the network, so we need to change the test OOBTest: move DISCARD down the stack, just above TP, and set up="0.5" instead of down="0.5".
                
> NAKACK2 / UNICAST2: last message sent to self may not get delivered
> -------------------------------------------------------------------
>
>                 Key: JGRP-1579
>                 URL: https://issues.jboss.org/browse/JGRP-1579
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 3.2.7, 3.3
>
>
> When A sends a message M that's received by A (M is either a multicast, or a unicast to A), and the message is dropped below NAKACK2 / UNICAST2, then A might *receive* M, but not *deliver* it if M is the last message sent.
> Scenario (for NAKACK2, but similar to UNICAST2):
> - A's table is: HD=9, HR=9
> - A sends M10
> - NAKACK2 adds M10: HD=9, HR=10 (highest-delivered is still 9, as we haven't removed M10 yet)
> - The transport drops M10
> - A sends no further messages
> - STABLE will make sure that A's HR is 10, but since no message was received, we won't *remove* any messages from A's table !
> --> The result is that although A *received* M10, it won't *deliver* M10 (until another message is received) !
> SOLUTION:
> - Maybe we can use the retransmit task to see if there are any unremoved messages in a table and - if so - remove them and pass them up the stack to the application.

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