com.asakusafw.runtime.flow.join

Class JoinResource<L extends org.apache.hadoop.io.Writable,R>

java.lang.Object

com.asakusafw.runtime.flow.join.JoinResource<L,R>

Type Parameters:

L - the left value type (provides lookup table for this type)

R - the right value type (looking up using this type)

All Implemented Interfaces:

FlowResource

public abstract class JoinResource<L extends org.apache.hadoop.io.Writable,R>
extends Object
implements FlowResource

An abstract implementation of resource for providing lookup table.

Constructor Summary

Constructors

Constructor and Description
JoinResource()

Method Summary

Modifier and Type	Method and Description
protected abstract LookUpKey	buildLeftKey(L value, LookUpKey buffer) Returns a lookup key from a left value.
protected abstract LookUpKey	buildRightKey(R value, LookUpKey buffer) Returns a lookup key from a right value.
protected LookUpTable.Builder<L>	createLookUpTable() Returns a builder for building a new lookup table.
protected abstract L	createValueObject() Returns a new left value object.
List<L>	find(R value) Looks up left values from the related right value.
protected abstract String	getCacheName() Returns the name of Hadoop distributed cache which provides contents of the lookup table.
void	setup(org.apache.hadoop.mapreduce.JobContext context) Initializes this resource.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.asakusafw.runtime.flow.FlowResource

cleanup

Constructor Detail

JoinResource

public JoinResource()

Method Detail

setup

public void setup(org.apache.hadoop.mapreduce.JobContext context)
           throws IOException,
                  InterruptedException

Description copied from interface: FlowResource

Initializes this resource.

Specified by:

setup in interface FlowResource

Parameters:

context - the current job context

Throws:

IOException - if failed to initialize this resource

InterruptedException - if interrupted while initializing this resource

createLookUpTable

protected LookUpTable.Builder<L> createLookUpTable()

Returns a builder for building a new lookup table.

Returns:

the created builder

getCacheName

protected abstract String getCacheName()

Returns the name of Hadoop distributed cache which provides contents of the lookup table.

Returns:

the name of Hadoop distributed cache

createValueObject

protected abstract L createValueObject()

Returns a new left value object.

Returns:

the created object

buildLeftKey

protected abstract LookUpKey buildLeftKey(L value,
                                          LookUpKey buffer)
                                   throws IOException

Returns a lookup key from a left value.

Parameters:

value - the left value

buffer - the key buffer

Returns:

the key object

Throws:

IOException - if error occurred while building the lookup key

IllegalArgumentException - if some parameters are null

buildRightKey

protected abstract LookUpKey buildRightKey(R value,
                                           LookUpKey buffer)
                                    throws IOException

Returns a lookup key from a right value.

Parameters:

value - the right value

buffer - the key buffer

Returns:

the key object

Throws:

IOException - if error occurred while building the lookup key

IllegalArgumentException - if some parameters are null

find

public List<L> find(R value)

Looks up left values from the related right value.

Parameters:

value - the right value

Returns:

the related left values

Throws:

LookUpException - if error was occurred while looking up the values