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https://issues.apache.org/jira/browse/HDFS-3110?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13245773#comment-13245773
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Todd Lipcon commented on HDFS-3110:
-----------------------------------
uld be declared {{static}}
- I think your new patch was actually a delta vs the old patch, instead of a
completely new one vs trunk. We need a new one for QA & commit
- When NewDirectByteBuffer returns NULL with no errno set, I think it's better
to set {{errno = ENOMEM;}} in an {{else}} clause -- just a little easier to
read.
- The new flag HDFS_SUPPORTS_DIRECT_READ is only used internally, so not sure
it belongs in the public header hdfs.h (this is what users include, right?).
Also, I think it would be better named something like
{{HDFS_FILE_SUPPORTS_DIRECT_READ}} since it refers to a specific stream rather
than the entire FS.
- Rather than declaring it as a {{const}} I think it's better to use an enum or
#define, since consts are a C++ thing and this code is mostly straight C. Also,
I think it's better to define it as (1 << 0) to indicate that this is going to
be in a bitfield.
- Please add a comment above the definition of the new flag referring to
hdfsFile_internal.flags, so we know where the flags end up.
- the new {{flags}} field should be unsigned -- {{uint32_t}} probably
- in the new test, why are you hardcoding {{localhost:20300}}? I'd think using
{{default}} as before is the right choice, since it will pick up whatever is
{{fs.default.name}} in your {{core-site.xml}} on the classpath. That way this
same test can be run against local FS or against DFS
> libhdfs implementation of direct read API
> -----------------------------------------
>
> Key: HDFS-3110
> URL: https://issues.apache.org/jira/browse/HDFS-3110
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: libhdfs
> Reporter: Henry Robinson
> Assignee: Henry Robinson
> Fix For: 0.24.0
>
> Attachments: HDFS-3110.0.patch, HDFS-3110.1.patch, HDFS-3110.2.patch
>
>
> Once HDFS-2834 gets committed, we can add support for the new API to libhdfs,
> which leads to significant performance increases when reading local data from
> C.
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