org.apache.hadoop.examples

Class PiEstimator.PiReducer

java.lang.Object

org.apache.hadoop.mapred.MapReduceBase

org.apache.hadoop.examples.PiEstimator.PiReducer

All Implemented Interfaces:

Closeable, AutoCloseable, JobConfigurable, Reducer<org.apache.hadoop.io.BooleanWritable,org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.WritableComparable<?>,org.apache.hadoop.io.Writable>

Enclosing class:

PiEstimator

public static class PiEstimator.PiReducer
extends MapReduceBase
implements Reducer<org.apache.hadoop.io.BooleanWritable,org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.WritableComparable<?>,org.apache.hadoop.io.Writable>

Reducer class for Pi estimation. Accumulate points inside/outside results from the mappers.

Constructor Summary

Constructors

Constructor and Description
PiEstimator.PiReducer()

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Reduce task done, write output to a file.
void	configure(JobConf job) Store job configuration.
void	reduce(org.apache.hadoop.io.BooleanWritable isInside, Iterator<org.apache.hadoop.io.LongWritable> values, OutputCollector<org.apache.hadoop.io.WritableComparable<?>,org.apache.hadoop.io.Writable> output, Reporter reporter) Accumulate number of points inside/outside results from the mappers.

Methods inherited from class java.lang.Object

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

Constructor Detail

PiEstimator.PiReducer

public PiEstimator.PiReducer()

Method Detail

configure

public void configure(JobConf job)

Store job configuration.

Specified by:

configure in interface JobConfigurable

Overrides:

configure in class MapReduceBase

Parameters:

job - the configuration

reduce

public void reduce(org.apache.hadoop.io.BooleanWritable isInside,
          Iterator<org.apache.hadoop.io.LongWritable> values,
          OutputCollector<org.apache.hadoop.io.WritableComparable<?>,org.apache.hadoop.io.Writable> output,
          Reporter reporter)
            throws IOException

Accumulate number of points inside/outside results from the mappers.

Specified by:

reduce in interface Reducer<org.apache.hadoop.io.BooleanWritable,org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.WritableComparable<?>,org.apache.hadoop.io.Writable>

Parameters:

isInside - Is the points inside?

values - An iterator to a list of point counts

output - dummy, not used here.

reporter -

Throws:

IOException

close

public void close()
           throws IOException

Reduce task done, write output to a file.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class MapReduceBase

Throws:

IOException