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https://issues.apache.org/jira/browse/YARN-1987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13985977#comment-13985977
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Jason Lowe commented on YARN-1987:
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Thanks for the feedback, Ming!
bq. LeveldbIterator.close rethrows IOException instead of DBException. Just
wonder which is better, given JniDBFactory.factory.open throws DBException.
JniDBFactory.factory.open throws NativeDB.DBException which is an IOException
rather than the runtime DBException. Also since close() already declares that
it can throw IOException which callers either have to handle or propagate it
seemed better to leverage that declared exception than a runtime exception
which callers can easily overlook.
bq. It seems "store open via JniDBFactory.factory.open" can also be useful to
put into a wrapper class, to take care of "catch the exception if the store
doesn't exist and create a new one".
If all one cares about is to make sure the database is created even if it
doesn't exist then that's already covered by the leveldb interfaces by calling
createIfMissing() on the options passed to the open call. In the NM restart
case I wanted to know when the database was being created so the code can
either check the existing schema version or set the schema version,
respectively. If that's something that needs to be put in a utility method
then I agree it's a separate JIRA.
> Wrapper for leveldb DBIterator to aid in handling database exceptions
> ---------------------------------------------------------------------
>
> Key: YARN-1987
> URL: https://issues.apache.org/jira/browse/YARN-1987
> Project: Hadoop YARN
> Issue Type: Improvement
> Affects Versions: 2.4.0
> Reporter: Jason Lowe
> Assignee: Jason Lowe
> Attachments: YARN-1987.patch
>
>
> Per discussions in YARN-1984 and MAPREDUCE-5652, it would be nice to have a
> utility wrapper around leveldb's DBIterator to translate the raw
> RuntimeExceptions it can throw into DBExceptions to make it easier to handle
> database errors while iterating.
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