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https://issues.apache.org/jira/browse/HDFS-9117?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14978833#comment-14978833
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Bob Hansen commented on HDFS-9117:
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The current design has the core of the C++ engine (FileSystem, InputStream,
etc.) dependent solely on the Options class, as we would all like. I believe
that the Configuration class should be part of the larger C++ API, however,
since it is a requirement for interoperability with deployed installations.
I propose we leave the base Configuration class in lib/common, and move the
hdfs_configuration class to lib/config. The HDFSConfiguration class will
continue to be responsible for mapping keys to hdfs::Option members and
producing the hdfs::Option object that the FileSystem and friends will consume.
Does that seem an appropriate approach?
bq. Environment variables and substitutions are clearly platform-dependent.
getenv is part of the C standard library, and the substitutions are entirely
the purview of the Java and C++ Configuration implementation, so I don't see
how they are at all platform-dependent. We can wrap them in configuration
#ifdefs to support platforms that for some reason don't support the C standard
library, but I don't see that as being a great service to our consumer base.
The configuration tests use setenv, which is available on all unix-y platforms.
While I hope this library will eventually support Windows clients, we don't
currently build or test on that platform, and I expect the setenv/_putenv
refactoring will be the smallest part of the work. Again, to guard against
that, we can #ifdef out those tests based on the available capabilities.
> Config file reader / options classes for libhdfs++
> --------------------------------------------------
>
> Key: HDFS-9117
> URL: https://issues.apache.org/jira/browse/HDFS-9117
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs-client
> Affects Versions: HDFS-8707
> Reporter: Bob Hansen
> Assignee: Bob Hansen
> Attachments: HDFS-9117.HDFS-8707.001.patch,
> HDFS-9117.HDFS-8707.002.patch, HDFS-9117.HDFS-8707.003.patch,
> HDFS-9117.HDFS-8707.004.patch, HDFS-9117.HDFS-8707.005.patch,
> HDFS-9117.HDFS-8707.006.patch, HDFS-9117.HDFS-8707.008.patch,
> HDFS-9117.HDFS-8707.009.patch, HDFS-9117.HDFS-9288.007.patch
>
>
> For environmental compatability with HDFS installations, libhdfs++ should be
> able to read the configurations from Hadoop XML files and behave in line with
> the Java implementation.
> Most notably, machine names and ports should be readable from Hadoop XML
> configuration files.
> Similarly, an internal Options architecture for libhdfs++ should be developed
> to efficiently transport the configuration information within the system.
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