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https://issues.apache.org/jira/browse/HDFS-5096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13795766#comment-13795766
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Colin Patrick McCabe commented on HDFS-5096:
--------------------------------------------
Chris-- yeah, the comments were wrong; thanks for finding that. Should be
fixed in the new version I'm about to post.
Andrew: I renamed {{TestImplicitBlocksList}} to {{TestCachedBlocksList}} and
increased the size of the lists being tested to 8000, from 4. I renamed
{{IntrusiveList}} to {{IntrusiveCollection}}, and made it implement
{{java.util.Collection}}. I did check out the {{Deque}} and {{Queue}] classes,
but they added everything in {{Collection}} and then a ton more methods,
including many that we never used. {{Collection}} is standard and it's a
"reasonably" small interface. I also converted the implicit linked list to use
triplets of { list, prev, cur } to match up with BlockInfo.
> Automatically cache new data added to a cached path
> ---------------------------------------------------
>
> Key: HDFS-5096
> URL: https://issues.apache.org/jira/browse/HDFS-5096
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, namenode
> Reporter: Andrew Wang
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-5096-caching.005.patch,
> HDFS-5096-caching.006.patch, HDFS-5096-caching.009.patch,
> HDFS-5096-caching.010.patch
>
>
> For some applications, it's convenient to specify a path to cache, and have
> HDFS automatically cache new data added to the path without sending a new
> caching request or a manual refresh command.
> One example is new data appended to a cached file. It would be nice to
> re-cache a block at the new appended length, and cache new blocks added to
> the file.
> Another example is a cached Hive partition directory, where a user can drop
> new files directly into the partition. It would be nice if these new files
> were cached.
> In both cases, this automatic caching would happen after the file is closed,
> i.e. block replica is finalized.
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