[infinispan-issues] [JBoss JIRA] (ISPN-3558) PutForExternalRead won't work after a clear(), when both in same tx

[William Burns (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-3558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12808698#comment-12808698 ] 

William Burns commented on ISPN-3558:
-------------------------------------

The provided test case should indeed fail.

The reason being is that putForExternalRead is invoked outside of any current transaction using putIfAbsent semantics.  So in this case the current tx is suspended and a putIfAbsent is invoked in which case it fails since the value is still technically there since it isn't done in the tx that has a clear.  Afterwards the original tx is resumed and the get returns nothing since the clear has removed it in it's context.

# Currently clear takes out locks (if needed) and stores in the context any values it was clearing out.  This means that if a a new entry is committed after clear is invoked (not yet committed) that you can use get to retrieve it since the clear didn't see that value (kinda like a write skew we don't detect).
# PFER does a putIfAbsent so the cache must not contain that value for it to work

I will add some test cases to verify these behaviors for the JIRA though.
                
> PutForExternalRead won't work after a clear(), when both in same tx
> -------------------------------------------------------------------
>
>                 Key: ISPN-3558
>                 URL: https://issues.jboss.org/browse/ISPN-3558
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 5.3.0.Final, 6.0.0.Beta1
>            Reporter: Galder Zamarreño
>            Assignee: William Burns
>             Fix For: 6.0.0.CR1, 6.0.0.Final
>
>
> {code}
>    public void testPutForExternalReadAfterClear() throws Exception {
>       cache.put(1, "v1");
>       tm().begin();
>       try {
>          cache.getAdvancedCache().clear();
>          cache.putForExternalRead(1, "v1");
>          assertEquals("v1", cache.get(1));
>       } finally {
>          tm().commit();
>       }
>    }
> {code}

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