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From "Lewis John McGibbney (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (GORA-170) Getting a BufferUnderflowException in class CassandraColumn, method fromByteBuffer()
Date Thu, 11 Oct 2012 13:47:03 GMT

    [ https://issues.apache.org/jira/browse/GORA-170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13474157#comment-13474157

Lewis John McGibbney commented on GORA-170:

I was getting it during a local crawl using Nutch 2.x. I'll try to get a more concrete idea
of how to reproduce in due course and post back here.
> 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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