org.apache.hadoop.mapreduce
Class ContextFactory

java.lang.Object
  org.apache.hadoop.mapreduce.ContextFactory

public class ContextFactory
extends Object

A factory to allow applications to deal with inconsistencies between MapReduce Context Objects API between hadoop-0.20 and later versions.

Constructor Summary

ContextFactory()

Method Summary

static JobContext	cloneContext(JobContext original, org.apache.hadoop.conf.Configuration conf) Clone a JobContext or TaskAttemptContext with a new configuration.
static <K1,V1,K2,V2> Mapper.Context	cloneMapContext(MapContext<K1,V1,K2,V2> context, org.apache.hadoop.conf.Configuration conf, RecordReader<K1,V1> reader, RecordWriter<K2,V2> writer) Copy a custom WrappedMapper.Context, optionally replacing the input and output.

Methods inherited from class java.lang.Object

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

Constructor Detail

ContextFactory

public ContextFactory()

Method Detail

cloneContext

public static JobContext cloneContext(JobContext original,
                                      org.apache.hadoop.conf.Configuration conf)
                               throws IOException,
                                      InterruptedException

Clone a JobContext or TaskAttemptContext with a new configuration.

Parameters:

original - the original context

conf - the new configuration

Returns:

a new context object

Throws:

InterruptedException

IOException

cloneMapContext

public static <K1,V1,K2,V2> Mapper.Context cloneMapContext(MapContext<K1,V1,K2,V2> context,
                                                           org.apache.hadoop.conf.Configuration conf,
                                                           RecordReader<K1,V1> reader,
                                                           RecordWriter<K2,V2> writer)
                                      throws IOException,
                                             InterruptedException

Copy a custom WrappedMapper.Context, optionally replacing the input and output.

Type Parameters:

K1 - input key type

V1 - input value type

K2 - output key type

V2 - output value type

Parameters:

context - the context to clone

conf - a new configuration

reader - Reader to read from. Null means to clone from context.

writer - Writer to write to. Null means to clone from context.

Returns:

a new context. it will not be the same class as the original.

Throws:

IOException

InterruptedException