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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7444) Add Checksum API to verify and calculate checksums "in bulk"
Date Wed, 13 Jul 2011 03:14:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13064314#comment-13064314
] 

Tsz Wo (Nicholas), SZE commented on HADOOP-7444:
------------------------------------------------

+1 patch looks good.  It won't work for 64-bit checksum.  I think it is fine, provided that
the existing code may also not work for 64-bit checksums.

> Add Checksum API to verify and calculate checksums "in bulk"
> ------------------------------------------------------------
>
>                 Key: HADOOP-7444
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7444
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>         Attachments: hadoop-7444.txt, hadoop-7444.txt, hadoop-7444.txt
>
>
> Currently, the various checksum types only provide the capability to calculate the checksum
of a range of a byte array. For HDFS-2080, it's advantageous to provide an API that, given
a buffer with some number of "checksum chunks", can either calculate or verify the checksums
of all of the chunks. For example, given a 4KB buffer and a 512-byte chunk size, it would
calculate or verify 8 CRC32s in one call.
> This allows efficient JNI-based checksum implementations since the cost of crossing the
JNI boundary is amortized across many computations.

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