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From "Tudor Scurtu (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-5625) Avoid byte buffer allocations when reading a value from a Result object
Date Tue, 27 Mar 2012 14:44:26 GMT

     [ https://issues.apache.org/jira/browse/HBASE-5625?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Tudor Scurtu updated HBASE-5625:
--------------------------------

    Attachment: 5625v3.txt

@Zhihong:
I initially submitted a minimalistic version so I wouldn't have to make extensive modifications
after reviews. Now the method is called from a unit test class.

The variable names were copied from existing methods and I wanted them to have a uniform naming
scheme. I renamed the variables, but not the method parameters.

The same for the method comment.

Implemented code style comments.

@stack:
Implemented code style comments.

Added check for buffer size.

Created 'KeyValue.checkParameters()' method. Should 'createEmptyByteArray()' call it as well?

'containsNonEmptyColumn()' checks if the value exists & is not empty; 'containsEmptyColumn()'
checks if the value exists & is empty. If you would have only one, for the other case
you would have to actually read the value and check it.

Moved most 'loadValue()' functionality to 'KeyValue'. This raises a problem: how do we elegantly
treat the case when the buffer (provided from 'Result') isn't big enough?

Refactored 'Result.getSearchTerm()' as another 'KeyValue.createFirstOnRow()'.

The new 'binarySearch()' method avoids allocating a byte array.

We run incremental jobs that update values; we also have to read different values form the
same row in different places.
                
> Avoid byte buffer allocations when reading a value from a Result object
> -----------------------------------------------------------------------
>
>                 Key: HBASE-5625
>                 URL: https://issues.apache.org/jira/browse/HBASE-5625
>             Project: HBase
>          Issue Type: Improvement
>          Components: client
>    Affects Versions: 0.92.1
>            Reporter: Tudor Scurtu
>              Labels: patch
>         Attachments: 5625.txt, 5625v2.txt, 5625v3.txt
>
>
> When calling Result.getValue(), an extra dummy KeyValue and its associated underlying
byte array are allocated, as well as a persistent buffer that will contain the returned value.
> These can be avoided by reusing a static array for the dummy object and by passing a
ByteBuffer object as a value destination buffer to the read method.
> The current functionality is maintained, and we have added a separate method call stack
that employs the described changes. I will provide more details with the patch.
> Running tests with a profiler, the reduction of read time seems to be of up to 40%.

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