org.apache.pig.scripting.jruby

Class JrubyEvalFunc

java.lang.Object

org.apache.pig.EvalFunc<java.lang.Object>

org.apache.pig.scripting.jruby.JrubyEvalFunc

public class JrubyEvalFunc
extends EvalFunc<java.lang.Object>

This class serves at the bridge between Ruby methods that are registered with and extend PigUdf, and their execution in Pig. An instance of the containing class is created, and their method name will be called against that instance. If they have a schema function associated, then when outputSchema is called, that function will be given the input Schema and the output will be given to Pig.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.pig.EvalFunc

EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
JrubyEvalFunc(java.lang.String filename, java.lang.String functionName) The constructor for this class registers the filename of the Ruby script and the name of the method we care about.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	exec(Tuple tuple) The exec method passes the tuple argument to the Ruby function, and converts the result back to Pig.
Schema	outputSchema(Schema input) This method uses the schema method of the function encapsulation object to get the Schema information for the Ruby method.

Methods inherited from class org.apache.pig.EvalFunc

addCredentials, allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, needEndOfAllInputProcessing, progress, setEndOfAllInput, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JrubyEvalFunc

public JrubyEvalFunc(java.lang.String filename,
                     java.lang.String functionName)
              throws java.io.IOException

The constructor for this class registers the filename of the Ruby script and the name of the method we care about. The difference between function name and method name is that the former is the name that was used to register the function, whereas the method name is the actual method that must be invoked. The two are often the same, but not always. functionName is the key to the list of EvalFuncs that are registered.

Throws:

java.io.IOException

Method Detail

exec

public java.lang.Object exec(Tuple tuple)
                      throws java.io.IOException

The exec method passes the tuple argument to the Ruby function, and converts the result back to Pig.

Specified by:

exec in class EvalFunc<java.lang.Object>

Parameters:

tuple - the Tuple to be processed.

Returns:

result, of type T.

Throws:

java.io.IOException

outputSchema

public Schema outputSchema(Schema input)

This method uses the schema method of the function encapsulation object to get the Schema information for the Ruby method.

Overrides:

outputSchema in class EvalFunc<java.lang.Object>

Parameters:

input - Schema of the input

Returns:

Schema of the output