org.apache.giraph.reducers.impl

Class KryoWrappedReduceOperation<S,R>

java.lang.Object

org.apache.giraph.reducers.impl.KryoWrappedReduceOperation<S,R>

Type Parameters:

S - Single value type

R - Reduced value type

All Implemented Interfaces:

ReduceOperation<S,KryoWritableWrapper<R>>, org.apache.hadoop.io.Writable

Direct Known Subclasses:

CollectPrimitiveReduceOperation, CollectReduceOperation, CollectTuplesOfPrimitivesReduceOperation, TopNReduce

public abstract class KryoWrappedReduceOperation<S,R>
extends Object
implements ReduceOperation<S,KryoWritableWrapper<R>>

Reduce operation which wraps reduced value in KryoWritableWrapper, so we don't need to worry about it being writable

Constructor Summary

Constructors

Constructor and Description
KryoWrappedReduceOperation()

Method Summary

Modifier and Type	Method and Description
KryoWritableWrapper<R>	createInitialValue() Return new reduced value which is neutral to reduce operation.
abstract R	createValue() Look at ReduceOperation.createValue.
void	readFields(DataInput dataInput)
KryoWritableWrapper<R>	reduce(KryoWritableWrapper<R> wrapper, S value) Add a new value.
abstract void	reduce(R reduceInto, S valueToReduce) Look at ReduceOperation.reduce.
KryoWritableWrapper<R>	reduceMerge(KryoWritableWrapper<R> wrapper, KryoWritableWrapper<R> wrapperToReduce) Add partially reduced value to current partially reduced value.
abstract void	reduceMerge(R reduceInto, R valueToReduce) Look at ReduceOperation.reduceMerge.
void	write(DataOutput dataOutput)

Methods inherited from class java.lang.Object

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

Constructor Detail

KryoWrappedReduceOperation

public KryoWrappedReduceOperation()

Method Detail

reduce

public abstract void reduce(R reduceInto,
                            S valueToReduce)

Look at ReduceOperation.reduce.

Parameters:

reduceInto - Partial value into which to reduce and store the result

valueToReduce - Single value to be reduced

reduceMerge

public abstract void reduceMerge(R reduceInto,
                                 R valueToReduce)

Look at ReduceOperation.reduceMerge.

Parameters:

reduceInto - Partial value into which to reduce and store the result

valueToReduce - Partial value to be reduced

createValue

public abstract R createValue()

Look at ReduceOperation.createValue.

Returns:

Neutral value

createInitialValue

public final KryoWritableWrapper<R> createInitialValue()

Description copied from interface: ReduceOperation

Return new reduced value which is neutral to reduce operation.

Specified by:

createInitialValue in interface ReduceOperation<S,KryoWritableWrapper<R>>

Returns:

Neutral value

reduce

public final KryoWritableWrapper<R> reduce(KryoWritableWrapper<R> wrapper,
                                           S value)

Description copied from interface: ReduceOperation

Add a new value. Needs to be commutative and associative Commonly, returned value should be same as curValue argument.

Specified by:

reduce in interface ReduceOperation<S,KryoWritableWrapper<R>>

Parameters:

wrapper - Partial value into which to reduce and store the result

value - Single value to be reduced

Returns:

reduced value

reduceMerge

public final KryoWritableWrapper<R> reduceMerge(KryoWritableWrapper<R> wrapper,
                                                KryoWritableWrapper<R> wrapperToReduce)

Description copied from interface: ReduceOperation

Add partially reduced value to current partially reduced value. Commonly, returned value should be same as curValue argument.

Specified by:

reduceMerge in interface ReduceOperation<S,KryoWritableWrapper<R>>

Parameters:

wrapper - Partial value into which to reduce and store the result

wrapperToReduce - Partial value to be reduced

Returns:

reduced value

write

public void write(DataOutput dataOutput)
           throws IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Throws:

IOException

readFields

public void readFields(DataInput dataInput)
                throws IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Throws:

IOException