org.apache.hadoop.mapreduce
Class TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

java.lang.Object
  org.apache.hadoop.mapreduce.JobContext
      org.apache.hadoop.mapreduce.TaskAttemptContext
          org.apache.hadoop.mapreduce.TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

Type Parameters:

KEYIN - the input key type for the task

VALUEIN - the input value type for the task

KEYOUT - the output key type for the task

VALUEOUT - the output value type for the task

All Implemented Interfaces:

Progressable

Direct Known Subclasses:

MapContext, ReduceContext

public abstract class TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>
extends TaskAttemptContext
implements Progressable

A context object that allows input and output from the task. It is only supplied to the Mapper or Reducer.

Field Summary

Fields inherited from class org.apache.hadoop.mapreduce.JobContext

CACHE_ARCHIVES_VISIBILITIES, CACHE_FILE_VISIBILITIES, COMBINE_CLASS_ATTR, conf, credentials, INPUT_FORMAT_CLASS_ATTR, JOB_ACL_MODIFY_JOB, JOB_ACL_VIEW_JOB, JOB_CANCEL_DELEGATION_TOKEN, JOB_NAMENODES, MAP_CLASS_ATTR, OUTPUT_FORMAT_CLASS_ATTR, PARTITIONER_CLASS_ATTR, REDUCE_CLASS_ATTR, ugi, USER_LOG_RETAIN_HOURS

Constructor Summary

TaskInputOutputContext(Configuration conf, TaskAttemptID taskid, RecordWriter<KEYOUT,VALUEOUT> output, OutputCommitter committer, StatusReporter reporter)

Method Summary

Counter	getCounter(Enum<?> counterName)
Counter	getCounter(String groupName, String counterName)
abstract KEYIN	getCurrentKey() Get the current key.
abstract VALUEIN	getCurrentValue() Get the current value.
OutputCommitter	getOutputCommitter()
abstract boolean	nextKeyValue() Advance to the next key, value pair, returning null if at end.
void	progress() Report progress.
void	setStatus(String status) Set the current status of the task to the given string.
void	write(KEYOUT key, VALUEOUT value) Generate an output key/value pair.

Methods inherited from class org.apache.hadoop.mapreduce.TaskAttemptContext

getStatus, getTaskAttemptID

Methods inherited from class org.apache.hadoop.mapreduce.JobContext

getCombinerClass, getConfiguration, getCredentials, getGroupingComparator, getInputFormatClass, getJar, getJobID, getJobName, getMapOutputKeyClass, getMapOutputValueClass, getMapperClass, getNumReduceTasks, getOutputFormatClass, getOutputKeyClass, getOutputValueClass, getPartitionerClass, getReducerClass, getSortComparator, getWorkingDirectory

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskInputOutputContext

public TaskInputOutputContext(Configuration conf,
                              TaskAttemptID taskid,
                              RecordWriter<KEYOUT,VALUEOUT> output,
                              OutputCommitter committer,
                              StatusReporter reporter)

Method Detail

nextKeyValue

public abstract boolean nextKeyValue()
                              throws IOException,
                                     InterruptedException

Advance to the next key, value pair, returning null if at end.

Returns:

the key object that was read into, or null if no more

Throws:

IOException

InterruptedException

getCurrentKey

public abstract KEYIN getCurrentKey()
                             throws IOException,
                                    InterruptedException

Get the current key.

Returns:

the current key object or null if there isn't one

Throws:

IOException

InterruptedException

getCurrentValue

public abstract VALUEIN getCurrentValue()
                                 throws IOException,
                                        InterruptedException

Get the current value.

Returns:

the value object that was read into

Throws:

IOException

InterruptedException

write

public void write(KEYOUT key,
                  VALUEOUT value)
           throws IOException,
                  InterruptedException

Generate an output key/value pair.

Throws:

IOException

InterruptedException

getCounter

public Counter getCounter(Enum<?> counterName)

getCounter

public Counter getCounter(String groupName,
                          String counterName)

progress

public void progress()

Description copied from class: TaskAttemptContext

Report progress. The subtypes actually do work in this method.

Specified by:

progress in interface Progressable

Overrides:

progress in class TaskAttemptContext

setStatus

public void setStatus(String status)

Description copied from class: TaskAttemptContext

Set the current status of the task to the given string.

Overrides:

setStatus in class TaskAttemptContext

getOutputCommitter

public OutputCommitter getOutputCommitter()