[jboss-jira] [JBoss JIRA] Commented: (JGRP-1014) NAKACK: SET_DIGEST does not overwrite the digest

[Bela Ban (JIRA)]

    [ https://jira.jboss.org/jira/browse/JGRP-1014?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12476882#action_12476882 ] 

Bela Ban commented on JGRP-1014:
--------------------------------

STATE_TRANSFER and STREAMING_STATE_TRANSFER now use OVERWRITE_DIGEST instead of SET_DIGEST. So setting the digest to B:10 after the message B:11 set it to B:11 will reset the digest to B:10, therefore the B:11 message (whose state change was overwritten) will get retransmitted.

> NAKACK: SET_DIGEST does not overwrite the digest
> ------------------------------------------------
>
>                 Key: JGRP-1014
>                 URL: https://jira.jboss.org/jira/browse/JGRP-1014
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 2.8
>
>
> When we set a digest in NAKACK, we do not overwrite an element for a member if it already exists. With state transfer, the following issue can occur (see [1]):
> Scenario #2:
> - [NAKACK] D receives B:11 (digest is 11 now for B)
> - [NAKACK] D applies the digest: this does NOT reset the digest for B to #10, but it remains #11 !!
> - D delivers B:11 to the app, changes state
> - D sets state, overwriting the change from B:11
> --> B:11 will NOT get retransmitted as the digest in NAKACK contains it !
> --> B:11 is lost
> SOLUTION: maybe add a 'state' boolean to the setDigest() method and overwrite if true
> This is a regression in 2.8 only; 2.6.x and 2.4.x handle SET_DIGEST correctly and do overwrite the digest.
> [1] https://jira.jboss.org/jira/browse/JGRP-1013

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