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https://issues.apache.org/jira/browse/HDFS-9144?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bob Hansen updated HDFS-9144:
-----------------------------
Attachment: HDFS-9144.HDFS-8707.002.patch
Carried refactoring through the DN operations:
* Merged with the libhdfs C-API work
* Removed Trait templates for OO classes
* Removed Stream templates for OO classes
* Removed Handler templates for explicit callback signatures
* Single-read usage now goes FileSystem -open-> FileHandle -pread-> ephemeral
BlockReader
* Moved the ephemeral part of AsyncReadSome into the BlockReader, so the
BlockReader now keeps all the state for a single read operation
* Per [~wheat9]'s request, added initial cancellation code
* Included comments on DN connection re-use
There is opportunity for further work (removing more stream and callback
templates), but I think this stands as a good discrete unit of work.
I no longer classify as clean eyes, but my hope is that this is cleaner in
terms of:
* Clear abstractions and concerns
* Clearer threading models and lifecycles for major objects
* Easier for new developers to engage and understand
Please review in terms of those qualities.
> Refactor libhdfs into stateful/ephemeral objects
> ------------------------------------------------
>
> Key: HDFS-9144
> URL: https://issues.apache.org/jira/browse/HDFS-9144
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs-client
> Affects Versions: HDFS-8707
> Reporter: Bob Hansen
> Assignee: Bob Hansen
> Attachments: HDFS-9144.HDFS-8707.001.patch,
> HDFS-9144.HDFS-8707.002.patch
>
>
> In discussion for other efforts, we decided that we should separate several
> concerns:
> * A posix-like FileSystem/FileHandle object (stream-based, positional reads)
> * An ephemeral ReadOperation object that holds the state for
> reads-in-progress, which consumes
> * An immutable FileInfo object which holds the block map and file size (and
> other metadata about the file that we assume will not change over the life of
> the file)
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