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https://issues.apache.org/jira/browse/HDFS-5285?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz Wo (Nicholas), SZE updated HDFS-5285:
-----------------------------------------

    Attachment: h5285_20131002.patch

h5285_20131002.patch: fixes compilation errors.

> Flatten INodeFile hierarchy
> ---------------------------
>
>                 Key: HDFS-5285
>                 URL: https://issues.apache.org/jira/browse/HDFS-5285
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: namenode
>            Reporter: Tsz Wo (Nicholas), SZE
>            Assignee: Tsz Wo (Nicholas), SZE
>         Attachments: h5285_20131001.patch, h5285_20131002.patch
>
>
> For files, there are INodeFile, INodeFileUnderConstruction, 
> INodeFileWithSnapshot and INodeFileUnderConstructionWithSnapshot for 
> representing whether a file is under construction or whether it is in some 
> snapshot.  The following are two major problems of the current approach:
> - Java class does not support multiple inheritances so that 
> INodeFileUnderConstructionWithSnapshot cannot extend both 
> INodeFileUnderConstruction and INodeFileWithSnapshot.
> - The number of classes is exponential to the number of features.  Currently, 
> there are only two features, UnderConstruction and WithSnapshot.  The number 
> of classes is 2^2 = 4.  It is hard to add one more feature since the number 
> of classes will become 2^3 = 8.



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