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https://issues.apache.org/jira/browse/HADOOP-11452?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-11452:
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Attachment: HADOOP-11452-002.patch
Patch 002
move the error strings from FSDirRenameOp into FSExceptionMessages, then use
them in the base FileSystem.rename/3, the latter adding all the checks from the
HDFS impl.
This means the base impl fails on root directories, fails if dest==source,
doesn't delete the source if it == dest.
Also, pulled the check for an empty dir out of the method for an override
point. Why? Allows object stores to implement a more efficient check for a path
being a non-empty dir. The listFiles() command returns an array of all
children, which is very expensive on any DFS with many children, but awfully
expensive on an object store. Even if blobstores don't override the whole
method, they can override this (protected) method for performance.
*No tests*. This is not ready to go in, just shows what changes are needed in
the functional code. The checks in the base implementation now should match
that in HDFS, though possibly in a different order. The docs need to be synced
up, and a contract test suite for this rename written. Issue: add it to the
existing rename tests, or create a new suite? I'm minded to just add them to
the existing test case, so everything automatically picks it up. All base class
implementations should be have similarly: if one passes, they all should
> Revisit FileSystem.rename(path, path, options)
> ----------------------------------------------
>
> Key: HADOOP-11452
> URL: https://issues.apache.org/jira/browse/HADOOP-11452
> Project: Hadoop Common
> Issue Type: Task
> Components: fs
> Affects Versions: 2.7.3
> Reporter: Yi Liu
> Assignee: Steve Loughran
> Attachments: HADOOP-11452-001.patch, HADOOP-11452-002.patch
>
>
> Currently in {{FileSystem}}, {{rename}} with _Rename options_ is protected
> and with _deprecated_ annotation. And the default implementation is not
> atomic.
> So this method is not able to be used outside. On the other hand, HDFS has a
> good and atomic implementation. (Also an interesting thing in {{DFSClient}},
> the _deprecated_ annotations for these two methods are opposite).
> It makes sense to make public for {{rename}} with _Rename options_, since
> it's atomic for rename+overwrite, also it saves RPC calls if user desires
> rename+overwrite.
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