NIFI-11794 - Fix NPE + configure max attempts for Redis State Provider

[pvillard31]

Summary

NIFI-11794 - Fix NPE + configure max attempts for Redis State Provider

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[ottobackwards]

This looks good, is there a way to test this specifically that we should cover?

[pvillard31]

I tried adding a unit test showing the issue but didn't find a way to reproduce it. You have to simulate two nodes at the same time trying to access the same key.

[ottobackwards]

would a failure to connect over max attempts ( to get the null and new check) work? without the nodes at all? or would that fail a different way?

[ottobackwards]

then again, a null check is a pretty obvious fix there, maybe we don't need to....

[pvillard31]

That would not cause the null error. EXEC returns null in case the transaction has been aborted. So you'd need to simulate one node/thread to have a transaction starting with a WATCH on the key, then another node/thread completing a transaction on the same key, to have the first one receiving a null. The logs I shared in the JIRA comment are coming from a cluster that I patched with this fix.

[pvillard31]

Thanks @ottobackwards