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Date: Tue, 7 Apr 2015 06:15:12 +0000 (UTC)
From: "Jing Zhao (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12788008.1428072581000.11628.1428387312542@Atlassian.JIRA>
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 <JIRA.12788008.1428072581096@arcas>
Subject: [jira] [Commented] (HDFS-8058) Erasure coding: use BlockInfo[] for
 both striped and contiguous blocks in INodeFile
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    [ https://issues.apache.org/jira/browse/HDFS-8058?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14482661#comment-14482661 ] 

Jing Zhao commented on HDFS-8058:
---------------------------------

bq. In my thought, this would never happen, although the type is BlockInfo[], the actual instance type is BlockInfoContiguous[] or BlockInfoStriped[], and we also do assertBlock check before setBlock, addBlock, etc.

Yes, I understand the current patch can avoid mixed block types. But my concern is that the way depending on the logic hidden in the code, instead of the explicit data type, may be error prone (especially for other developers). Thus from the API point of view, currently I still prefer declaring {{BlockInfoContiguous[]}} and {{BlockInfoStriped[]}} separately.

> Erasure coding: use BlockInfo[] for both striped and contiguous blocks in INodeFile
> -----------------------------------------------------------------------------------
>
>                 Key: HDFS-8058
>                 URL: https://issues.apache.org/jira/browse/HDFS-8058
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>    Affects Versions: HDFS-7285
>            Reporter: Yi Liu
>            Assignee: Yi Liu
>         Attachments: HDFS-8058.001.patch, HDFS-8058.002.patch
>
>
> This JIRA is to use {{BlockInfo[] blocks}} for both striped and contiguous blocks in INodeFile.
> Currently {{FileWithStripedBlocksFeature}} keeps separate list for striped blocks, and the methods there duplicate with those in INodeFile, and current code need to judge {{isStriped}} then do different things. Also if file is striped, the {{blocks}} in INodeFile occupy a reference memory space.
> These are not necessary, and we can use the same {{blocks}} to make code more clear.
> I keep {{FileWithStripedBlocksFeature}} as empty for follow use: I will file a new JIRA to move {{dataBlockNum}} and {{parityBlockNum}} from *BlockInfoStriped* to INodeFile, since ideally they are the same for all striped blocks in a file, and store them in block will waste NN memory.


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