org.apache.giraph.block_app.reducers

Class TopNReduce<S extends Comparable<S>>

java.lang.Object

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

org.apache.giraph.block_app.reducers.TopNReduce<S>

Type Parameters:

S - Single value type, objects passed on workers

All Implemented Interfaces:

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

public class TopNReduce<S extends Comparable<S>>
extends KryoWrappedReduceOperation<S,PriorityQueue<S>>

Extracts top N largest elements

Constructor Summary

Constructors

Constructor and Description
TopNReduce()
TopNReduce(int capacity)

Method Summary

Modifier and Type	Method and Description
PriorityQueue<S>	createValue() Look at ReduceOperation.createValue.
void	readFields(DataInput in)
void	reduce(PriorityQueue<S> heap, S value) Look at ReduceOperation.reduce.
void	reduceMerge(PriorityQueue<S> reduceInto, PriorityQueue<S> toReduce) Look at ReduceOperation.reduceMerge.
void	write(DataOutput out)

Methods inherited from class org.apache.giraph.reducers.impl.KryoWrappedReduceOperation

createInitialValue, reduce, reduceMerge

Methods inherited from class java.lang.Object

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

Constructor Detail

TopNReduce

public TopNReduce(int capacity)

TopNReduce

public TopNReduce()

Method Detail

createValue

public PriorityQueue<S> createValue()

Description copied from class: KryoWrappedReduceOperation

Look at ReduceOperation.createValue.

Specified by:

createValue in class KryoWrappedReduceOperation<S extends Comparable<S>,PriorityQueue<S extends Comparable<S>>>

Returns:

Neutral value

reduce

public void reduce(PriorityQueue<S> heap,
                   S value)

Description copied from class: KryoWrappedReduceOperation

Look at ReduceOperation.reduce.

Specified by:

reduce in class KryoWrappedReduceOperation<S extends Comparable<S>,PriorityQueue<S extends Comparable<S>>>

Parameters:

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

value - Single value to be reduced

reduceMerge

public void reduceMerge(PriorityQueue<S> reduceInto,
                        PriorityQueue<S> toReduce)

Description copied from class: KryoWrappedReduceOperation

Look at ReduceOperation.reduceMerge.

Specified by:

reduceMerge in class KryoWrappedReduceOperation<S extends Comparable<S>,PriorityQueue<S extends Comparable<S>>>

Parameters:

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

toReduce - Partial value to be reduced

write

public void write(DataOutput out)
           throws IOException

Specified by:

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

Overrides:

write in class KryoWrappedReduceOperation<S extends Comparable<S>,PriorityQueue<S extends Comparable<S>>>

Throws:

IOException

readFields

public void readFields(DataInput in)
                throws IOException

Specified by:

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

Overrides:

readFields in class KryoWrappedReduceOperation<S extends Comparable<S>,PriorityQueue<S extends Comparable<S>>>

Throws:

IOException