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Posted to dev@gora.apache.org by "Kazuomi Kashii (JIRA)" <ji...@apache.org> on 2012/10/09 00:32:02 UTC

[jira] [Commented] (GORA-170) Getting a BufferUnderflowException in class CassandraColumn, method fromByteBuffer()

    [ https://issues.apache.org/jira/browse/GORA-170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13471924#comment-13471924 ] 

Kazuomi Kashii commented on GORA-170:
-------------------------------------

How can we re-produce this bug ?
I have set up Ubuntu environment to investigate.
(Sorry, I have had no time to check the status for a couple of months.)
                
> Getting a BufferUnderflowException in class CassandraColumn, method fromByteBuffer()
> ------------------------------------------------------------------------------------
>
>                 Key: GORA-170
>                 URL: https://issues.apache.org/jira/browse/GORA-170
>             Project: Apache Gora
>          Issue Type: Bug
>          Components: storage-cassandra
>    Affects Versions: 0.2.1
>         Environment: Not sure environment matters for this one but Ubuntu
>            Reporter: Chris Gerken
>            Priority: Blocker
>
> When using CassandraStore and GoraMapper to retrieve data previously stored in Cassandra, a BufferUnderflowException is being thrown in method fromByteBuffer() in class CassandraColumn.  This results in a complete failure of the hadoop job trying to use the Cassandra data.
> The problem seems to be caused by an invalid assumption in the (de) Serializer logic.  Serializers assume that the bytes in a ByteBuffer to be deserialized start at offset 0 (zero) in the ByteBuffer's internal buffer.  In fact, there are times when a ByteBuffer passed back from  the Hector/Thrift API will have its data start at a non-zero offset in its buffer.  When serializers are given these non-zero offset ByteBuffers an exception, usually BufferUnderflowException, is thrown.
> The suggested fix is to use the TbaseHelper class from Cassandra/Thrift:
>   import org.apache.thrift.TBaseHelper;
>   protected Object fromByteBuffer(Schema schema, ByteBuffer byteBuffer) {
>     Object value = null;
>     Serializer serializer = GoraSerializerTypeInferer.getSerializer(schema);
>     if (serializer == null) {
>       LOG.info("Schema is not supported: " + schema.toString());
>     } else {
>       ByteBuffer corrected = TBaseHelper.rightSize(byteBuffer);
>       value = serializer.fromByteBuffer(corrected);
>     }
>     return value;
>   }
>  

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