[jira] Work started: (HADOOP-941) Make Hadoop Record I/O Easier to use outside Hadoop

["Milind Bhandarkar (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-941?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on HADOOP-941 started by Milind Bhandarkar.

> Make Hadoop Record I/O Easier to use outside Hadoop
> ---------------------------------------------------
>
>                 Key: HADOOP-941
>                 URL: https://issues.apache.org/jira/browse/HADOOP-941
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: record
>    Affects Versions: 0.10.1
>         Environment: All
>            Reporter: Milind Bhandarkar
>         Assigned To: Milind Bhandarkar
>             Fix For: 0.11.0
>
>
> Hadoop record I/O can be used effectively outside of Hadoop. It would increase its utility if developers can use it without having to import hadoop classes, or having to depend on Hadoop jars. Following changes to the current translator and runtime are proposed.
> Proposed Changes:
> 1. Use java.lang.String as a native type for ustring (instead of Text.)
> 2. Provide a Buffer class as a native Java type for buffer (instead of BytesWritable), so that later BytesWritable could be implemented as following DDL:
> module org.apache.hadoop.io {
>   record BytesWritable {
>     buffer value;
>   }
> }
> 3. Member names in generated classes should not have prefixes 'm' before their names. In the above example, the private member name would be 'value' not 'mvalue' as it is done now.
> 4. Convert getters and setters to have CamelCase. e.g. in the above example the getter will be:
>   public Buffer getValue();
> 5. Provide a 'swiggable' C binding, so that processing the generated C code with swig allows it to be used in scripting languages such as Python and Perl.
> 6. The default --language="java" target would generate class code for records that would not have Hadoop dependency on WritableComparable interface, but instead would have "implements Record, Comparable". (i.e. It will not have write() and readFields() methods.) An additional option "--writable" will need to be specified on rcc commandline to generate classes that "implements Record, WritableComparable".
> 7. Optimize generated write() and readFields() methods, so that they do not have to create BinaryOutputArchive or BinaryInputArchive every time these methods are called on a record.
> 8. Implement ByteInStream and ByteOutStream for C++ runtime, as they will be needed for using Hadoop Record I/O with forthcoming C++ MapReduce framework (currently, only FileStreams are provided.)
> 9. Generate clone() methods for records in Java i.e. the generated classes should implement Cloneable.
> 10. As part of Hadoop build process, produce a tar bundle for Record I/O alone. This tar bundle will contain the translator classes and ant task (lib/rcc.jar), translator script (bin/rcc), Java runtime (recordio.jar) that includes org.apache.hadoop.record.*, sources for the java runtime (src/java), and c/c++ runtime sources with Makefiles (src/c++, src/c).
> 11. Make generated Java codes for maps and vectors use Java generics.
> These are the proposed user-visible changes. Internally, the translator will be restructured so that it is easier to plug-in translators for different targets.

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