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From "Colin Patrick McCabe (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7017) Implement OutputStream for libhdfs3
Date Wed, 12 Nov 2014 01:59:34 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14207524#comment-14207524

Colin Patrick McCabe commented on HDFS-7017:

Any update on this one?  I agree with the idea of combining {{LeaseManager}} and {{LeaseManagerImpl}}.
 I think perhaps you might have separated them to provide a way to inject behavior in unit
tests.  However, we can always come up with fault injectors, or tweak the configuration settings
to induce timeouts, like we do in the Java code.  Having all this indirection makes the code
hard to follow.

In general, I am not keen on the idea of singletons.  They're really just globals with a different
name and all of the same problems.  I think if possible we should have the {{LeaseManager}}
owned by the {{hdfsFS}} instance.  Then we can create it after the user calls {{hdfsConnect}}
+ {{hdfsOpen}} (for write), and destroy it when the user calls {{hdfsDisconnect}}.  In contrast,
if we make it a singleton, the application has no way to stop it once the library creates
it.  Using a singleton here also creates a lot of inconvenience during unit tests.  If this
is too much trouble to do in this patch, we can do it in a follow-on JIRA.

I also agree with the idea of punting the packet memory pool to a follow-on JIRA.

> Implement OutputStream for libhdfs3
> -----------------------------------
>                 Key: HDFS-7017
>                 URL: https://issues.apache.org/jira/browse/HDFS-7017
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: hdfs-client
>            Reporter: Zhanwei Wang
>            Assignee: Zhanwei Wang
>         Attachments: HDFS-7017-pnative.002.patch, HDFS-7017-pnative.003.patch, HDFS-7017-pnative.004.patch,
> Implement pipeline and OutputStream C++ interface

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