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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-7444) Add Checksum API to verify and calculate checksums "in bulk"
Date Wed, 06 Jul 2011 05:42:16 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-7444?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Todd Lipcon updated HADOOP-7444:
--------------------------------

    Attachment: hadoop-7444.txt

Fairly simple patch implementing this API.

Unfortunately it wasn't straightforward to use the new APIs from FSInputChecker, since that
class only has a Checksum instance and not a DataChecksum instance. We can tackle that as
an improvement later.

> 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
>         Attachments: 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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