Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: hdfs-issues@hadoop.apache.org
Date: Mon, 21 May 2012 04:12:41 +0000 (UTC)
From: "Todd Lipcon (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <725543014.2350.1337573561360.JavaMail.jiratomcat@issues-vm>
In-Reply-To: <231256565.2238.1337570921674.JavaMail.jiratomcat@issues-vm>
Subject: [jira] [Commented] (HDFS-3448) CLONE - Why open method in class
 DFSClient would compare old LocatedBlocks and new LocatedBlocks?
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/HDFS-3448?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279950#comment-13279950 ] 

Todd Lipcon commented on HDFS-3448:
-----------------------------------

Hi Li. {{Block.equals()}} already does what you're suggesting - it compares based on block ID alone - if the genstamp changes, the block is still considered equal.
                
> CLONE - Why open method in class DFSClient would compare old LocatedBlocks and new LocatedBlocks?
> -------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-3448
>                 URL: https://issues.apache.org/jira/browse/HDFS-3448
>             Project: Hadoop HDFS
>          Issue Type: Wish
>            Reporter: Li Junjun
>            Assignee: Todd Lipcon
>   Original Estimate: 168h
>  Remaining Estimate: 168h
>
>  I think there are two situations.
> 1,the file has been swapped with another file,we check the blockId,that's correct we throw Exceptions!
> 2,but if the file has not been swapped but has been appended ,we should just check the blockId ,and should not care about the block's stamp , because in fact we got the right and updated block list , cause file in hdfs can't be truncate .
> so how about we do it like this ?
> if ( oldIter.next().getBlock().getBlockId() != newIter.next().getBlock().getBlockId() ) { throw new IOException("Blocklist for " + src + " has changed!"); }
> after all , between two calls to openInfo() the file can be swapped and then appending,so we should not ignore the under construction file.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira