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https://issues.apache.org/jira/browse/HDFS-2656?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13453237#comment-13453237
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Colin Patrick McCabe commented on HDFS-2656:
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bq. For hdfsCopy/hdfsMove, any comments about their implementation without JNI?
In the JNI-based libhdfs, {{hdfsCopy}} calls {{FileUtil#copy}}. This method
basically just does what you would expect-- it opens an input stream for the
input file(s), and copies the bytes to the output file(s).
Probably the most complicated part of {{FileUtil#copy}} is that it works
recursively when used on directories. However, there's no special atomicity
semantics when {{FileUtil#copy}} copies a directory-- it just iterates through
the files in a directory and copies what it can. If the directory is updated
while it's iterating, that may or may not be reflected in the copy.
{{hdfsMove}} basically just invokes {{FileUtil#copy}} with {{deleteSource}} =
true.
So I think we should implement these methods in libwebhdfs using the methods
which are already present.
> Implement a pure c client based on webhdfs
> ------------------------------------------
>
> Key: HDFS-2656
> URL: https://issues.apache.org/jira/browse/HDFS-2656
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: webhdfs
> Reporter: Zhanwei.Wang
> Assignee: Jing Zhao
> Fix For: 2.0.3-alpha
>
> Attachments: HDFS-2656.patch, HDFS-2656.patch, HDFS-2656.patch,
> HDFS-2656.unfinished.patch, teragen_terasort_teravalidate_performance.png
>
>
> Currently, the implementation of libhdfs is based on JNI. The overhead of JVM
> seems a little big, and libhdfs can also not be used in the environment
> without hdfs.
> It seems a good idea to implement a pure c client by wrapping webhdfs. It
> also can be used to access different version of hdfs.
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