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From "Colin Patrick McCabe (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-573) Porting libhdfs to Windows
Date Thu, 31 Jul 2014 23:45:40 GMT

    [ https://issues.apache.org/jira/browse/HDFS-573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14081689#comment-14081689

Colin Patrick McCabe commented on HDFS-573:

bq. I have just one question though. My initial inclination was to put TYPE_CHECKED_PRINTF_FORMAT
in platform.h as well. However, I then backed that out and put the ifdef in exception.h, because
it has never been clear to me if exception.h is part of the public API

The only header file that's part of the public API is {{hdfs.h}}.  That's the only one we
export to end-users... nobody can even get access to the other ones without a Hadoop source
tree.  You should feel free to change, add, or remove things from any header file without
worrying about compatibility, as long as that header is not {{hdfs.h}}.

bq. BTW Colin, thanks for the code review. The work so far has been aimed at a straight port,
warts and all, but I'm happy to roll in a few more small fixes for existing problems while
I'm in here. I'll work on a v2 of the patch.

Thanks, Chris.  I think what you've got looks pretty good... I wish all libhdfs patches could
be this good :)

> Porting libhdfs to Windows
> --------------------------
>                 Key: HDFS-573
>                 URL: https://issues.apache.org/jira/browse/HDFS-573
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: libhdfs
>         Environment: Windows, Visual Studio 2008
>            Reporter: Ziliang Guo
>            Assignee: Chris Nauroth
>         Attachments: HDFS-573.1.patch
>   Original Estimate: 336h
>  Remaining Estimate: 336h
> The current C code in libhdfs is written using C99 conventions and also uses a few POSIX
specific functions such as hcreate, hsearch, and pthread mutex locks.  To compile it using
Visual Studio would require a conversion of the code in hdfsJniHelper.c and hdfs.c to C89
and replacement/reimplementation of the POSIX functions.  The code also uses the stdint.h
header, which is not part of the original C89, but there exists what appears to be a BSD licensed
reimplementation written to be compatible with MSVC floating around.  I have already done
the other necessary conversions, as well as created a simplistic hash bucket for use with
hcreate and hsearch and successfully built a DLL of libhdfs.  Further testing is needed to
see if it is usable by other programs to actually access hdfs, which will likely happen in
the next few weeks as the Condor Project continues with its file transfer work.
> In the process, I've removed a few what I believe are extraneous consts and also fixed
an incorrect array initialization where someone was attempting to initialize with something
like this: JavaVMOption options[noArgs]; where noArgs was being incremented in the code above.
 This was in the hdfsJniHelper.c file, in the getJNIEnv function.

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