Swaminathan Balachandran created HDDS-11443:
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Summary: Ozone Manager cache cannot rollback cache updates made by
validateAndUpdateCache in case of error response
Key: HDDS-11443
URL: https://issues.apache.org/jira/browse/HDDS-11443
Project: Apache Ozone
Issue Type: Bug
Reporter: Swaminathan Balachandran
Assignee: Swaminathan Balachandran
An addCacheEntry call directly updates the cache, there is no rollback strategy
in place, which would rollback the cache data structure before the ratis
transaction when an error response is returned. If the cache is updated and an
error response is returned, the cache could be in an inconsistent state.
E.g.
[https://github.com/apache/ozone/blame/831cd46ff48d75c0ea4f1c21f907deebbb5f3262/hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/request/snapshot/OMSnapshotPurgeRequest.java#L130-L133]
P.S. there could be happening in other requests as well.
The proposal is to have an uncommitted cache map which would be used to add the
delta entries. These entries would be merged to the main cache map if a success
response is returned otherwise the entries would be scrapped away.
The bigger problem is that, this could impact reads as well. Since
readFromCache could be reading from intermediate transaction data which could
be returning inconsistent results. Read from cache should only send commited
transaction data.
[~erose] [~hemantk] Correct me if I am wrong here.
cc: [~umamahesh]
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