[
https://issues.apache.org/jira/browse/PIG-1354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12853421#action_12853421
]
Dmitriy V. Ryaboy commented on PIG-1354:
----------------------------------------
The attached patch provides generic UDFs for invoking functions that return one
of the following Java classes: String, Integer, Long, Double, Float, or their
primitive equivalents. The same set of classes can serve as arguments to said
functions.
Static or non-static methods can be invoked (a non-static method is assumed to
be invoked on the first element in the argument list).
The method signature is supplied using Pig Latin's DEFINE statement.
Usage looks like this:
{code}
-- invoking a static method
DEFINE StringToLong InvokeForLong('java.lang.Long.valueOf', 'String')
longs = FOREACH strings GENERATE StringToLong(some_chararray);
-- invoking a method on an object
DEFINE StringConcat InvokeForString('java.lang.String.concat', 'String
String', 'false')
concatenations = FOREACH strings GENERATE StringConcat(str1, str2);
{code}
There is some overhead to using this technique vs writing a method-specific UDF
wrapper. In my tests, the dynamic version runs about 1.3x-1.8x slower than a
non-dynamic version for simple methods.
> UDFs for dynamic invocation of simple Java methods
> --------------------------------------------------
>
> Key: PIG-1354
> URL: https://issues.apache.org/jira/browse/PIG-1354
> Project: Pig
> Issue Type: New Feature
> Affects Versions: 0.8.0
> Reporter: Dmitriy V. Ryaboy
> Assignee: Dmitriy V. Ryaboy
> Fix For: 0.8.0
>
> Attachments: PIG-1354.patch
>
>
> The need to create wrapper UDFs for simple Java functions creates unnecessary
> work for Pig users, slows down the development process, and produces a lot of
> trivial classes. We can use Java's reflection to allow invoking a number of
> methods on the fly, dynamically, by creating a generic UDF to accomplish this.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
