[jboss-jira] [JBoss JIRA] Resolved: (JGRP-1347) UNICAST/UNICAST2: message can get delivered multiple times

[Bela Ban (JIRA)]

     [ https://issues.jboss.org/browse/JGRP-1347?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban resolved JGRP-1347.
----------------------------

    Resolution: Done


Added synchronization around fetching the initial window. After that, messages can be added concurrently

> UNICAST/UNICAST2: message can get delivered multiple times
> ----------------------------------------------------------
>
>                 Key: JGRP-1347
>                 URL: https://issues.jboss.org/browse/JGRP-1347
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 2.12.2, 3.0
>
>
> In handleDataReceived(), when our connection is not the same as the conn_id of the incoming message, we (1) remove the window and (2) create a new one and add it.
> However, (1) and (2) are *not* synchronized: when multiple threads go through this code concurrently, we could have a sequence 1-2-1, meaning the window is removed, a new one is created, but then - because another thread got conn_id != our conn_id true, the window will be removed again !
> This means that a message #1 might get added to the new window and delivered to the app, and then the same thing could happen again, because we re-create the window again !
> SOLUTION: synchronization around: check for conn_id match, removal and creation of the new window

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