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From "Sanjay Radia (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2470) Open and isDir should be removed from ClientProtocol
Date Fri, 07 Mar 2008 23:57:46 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2470?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12576449#action_12576449

Sanjay Radia commented on HADOOP-2470:

Being able to distinguish between open counts and getLocation counts is not necessary.
>From that point getting rid of the open rpc call seems reasonable. 

The only advantage the open call has (and we don't take advantage of this) is to have only
check the file perms once and for the future getLocations of the opened file,  pass the openFileId.

(Current getLocations has the pathname). Such as scheme
would be more efficient for permission checking and would also have the desired property that
once you have opened a file for reading you can continue to read it in face of permission
changes. The cost of doing this is to maintain a openFileDescriptors on the NN side + leases
to recover. The cost of this would be quite high given that NN can support tens of thousands
readers. I doubt if we will ever maintain open-file descriptors on NN side.

SO my vote is +1

> Open and isDir should be removed from ClientProtocol
> ----------------------------------------------------
>                 Key: HADOOP-2470
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2470
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.15.1
>            Reporter: Hairong Kuang
>            Assignee: Tsz Wo (Nicholas), SZE
> Methods open and isDir in ClientProtocol are no longer used. DFSClient uses getBlockLocations
and getFileInfo instead. So open and isDir should be removed from ClientProtocol.

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