[infinispan-issues] [JBoss JIRA] (ISPN-3419) Write Skew check must be performed only in the primary owner

[Pedro Ruivo (JIRA)]

     [ https://issues.jboss.org/browse/ISPN-3419?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on ISPN-3419 started by Pedro Ruivo.

> Write Skew check must be performed only in the primary owner
> ------------------------------------------------------------
>
>                 Key: ISPN-3419
>                 URL: https://issues.jboss.org/browse/ISPN-3419
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 6.0.0.Alpha2
>            Reporter: Pedro Ruivo
>            Assignee: Pedro Ruivo
>             Fix For: 6.0.0.Alpha3
>
>
> The following case can create data inconsistency:
> A: txA reads k with version v1 and writes on k (say valueA)
> primary-owner of k: txA acquire lock on k, validates and return v2 (increment(v1))
> non-primary-onwer of k: txA registers a backup lock, validates and returns v2 (increment(v1))
> A: txA commits with version v2.
> primary-owner of k: applies txA //commit in the non-primary-owner is delayed
> B: txB remote reads k with version v2 and writes on k (say valueB) and prepare the transaction
> primary-owner of k: txB waits until the lock is relased.
> non-primary-onwer of k: txA registers a backup lock, validates and returns v2 (increment(v1), because it has not applied the txA)
> primary-owner of k: lock is release, txB is validated and it return v3 (increment(v2))
> B collects all the response and merge them. However, the map.value() can return first the response from primary-owner (v3) and them the response from the non-primary-owner (v2). The result version map will be k=>v2.
> txB will update k with the same previous version and a different value. from here the data will become inconsistent. 

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