[jira] [Created] (AVRO-2592) Avro decimal fails on certain conditions - ByteBuffer.position() is the root cause

["Werner Daehn (Jira)" <ji...@apache.org>]

Werner Daehn created AVRO-2592:
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             Summary: Avro decimal fails on certain conditions - ByteBuffer.position() is the root cause
                 Key: AVRO-2592
                 URL: https://issues.apache.org/jira/browse/AVRO-2592
             Project: Apache Avro
          Issue Type: Bug
          Components: java
    Affects Versions: 1.9.1
            Reporter: Werner Daehn


The Decimal Conversion from/to Bytebuffer is using the methods that consider the current position, e.g. remaining().

[https://github.com/rdblue/avro-java/blob/master/avro/src/main/java/org/apache/avro/Conversions.java#L83]

 

At first sight that looks like a good idea. But actually it creates all sorts of problems.

For example this code fails with "Zero Length BigInteger":

 
{code:java}
BigDecimal d = BigDecimal.valueOf(3.1415); BigDecimal d = BigDecimal.valueOf(3.1415);

Decimal decimaltype = LogicalTypes.decimal(7, 4); ByteBuffer buffer = DECIMAL_CONVERTER.toBytes(d, null, decimaltype);

System.out.println(DECIMAL_CONVERTER.fromBytes(buffer, null, decimaltype).toString());

BigDecimal n = DECIMAL_CONVERTER.fromBytes(buffer, null, decimaltype);

System.out.println(n.toString());{code}
 

Reason is obvious. The first call to fromBytes() moves the position from 0 to the last byte. The second invocation reads from the last position, hence zero records.

There are other situations this might cause issues, e.g. a user might create the ByteBuffer via other means and it is normal that the position is after the last byte. Then the serialization would not work either. And many other.

As the ByteBuffer is used to wrap a single BigDecimal, I would suggest to remove all position-aware/setting methods and read/write from position zero.

 

 



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