org.apache.hadoop.mapreduce

Interface 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 Superinterfaces:

JobContext, org.apache.hadoop.util.Progressable, TaskAttemptContext

All Known Subinterfaces:

MapContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>, ReduceContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

All Known Implementing Classes:

MapContextImpl, Mapper.Context, ReduceContextImpl, Reducer.Context, TaskInputOutputContextImpl, WrappedMapper.Context, WrappedReducer.Context

public interface TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>
extends TaskAttemptContext

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 interface org.apache.hadoop.mapreduce.JobContext

CACHE_ARCHIVES_VISIBILITIES, CACHE_FILE_VISIBILITIES, COMBINE_CLASS_ATTR, INPUT_FORMAT_CLASS_ATTR, JAR_UNPACK_PATTERN, JOB_ACL_MODIFY_JOB, JOB_ACL_VIEW_JOB, JOB_CANCEL_DELEGATION_TOKEN, JOB_NAMENODES, MAP_CLASS_ATTR, MAP_MEMORY_PHYSICAL_MB, MAP_OUTPUT_COLLECTOR_CLASS_ATTR, MAPREDUCE_TASK_CLASSPATH_PRECEDENCE, OUTPUT_FORMAT_CLASS_ATTR, PARTITIONER_CLASS_ATTR, REDUCE_CLASS_ATTR, REDUCE_MEMORY_PHYSICAL_MB, SHUFFLE_CONSUMER_PLUGIN_ATTR, USER_LOG_RETAIN_HOURS

Method Summary

Methods

Modifier and Type	Method and Description
KEYIN	getCurrentKey() Get the current key.
VALUEIN	getCurrentValue() Get the current value.
OutputCommitter	getOutputCommitter() Get the OutputCommitter for the task-attempt.
boolean	nextKeyValue() Advance to the next key, value pair, returning null if at end.
void	write(KEYOUT key, VALUEOUT value) Generate an output key/value pair.

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

getCounter, getCounter, getStatus, getTaskAttemptID, setStatus

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

getArchiveClassPaths, getArchiveTimestamps, getCacheArchives, getCacheFiles, getCombinerClass, getCombinerKeyGroupingComparator, getConfiguration, getCredentials, getFileClassPaths, getFileTimestamps, getGroupingComparator, getInputFormatClass, getJar, getJobID, getJobName, getJobSetupCleanupNeeded, getLocalCacheArchives, getLocalCacheFiles, getMapOutputKeyClass, getMapOutputValueClass, getMapperClass, getMaxMapAttempts, getMaxReduceAttempts, getNumReduceTasks, getOutputFormatClass, getOutputKeyClass, getOutputValueClass, getPartitionerClass, getProfileEnabled, getProfileParams, getReducerClass, getSortComparator, getSymlink, getUser, getWorkingDirectory, userClassesTakesPrecedence

Methods inherited from interface org.apache.hadoop.util.Progressable

progress

Method Detail

nextKeyValue

boolean nextKeyValue()
                     throws java.io.IOException,
                            java.lang.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:

java.io.IOException

java.lang.InterruptedException

getCurrentKey

KEYIN getCurrentKey()
                    throws java.io.IOException,
                           java.lang.InterruptedException

Get the current key.

Returns:

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

Throws:

java.io.IOException

java.lang.InterruptedException

getCurrentValue

VALUEIN getCurrentValue()
                        throws java.io.IOException,
                               java.lang.InterruptedException

Get the current value.

Returns:

the value object that was read into

Throws:

java.io.IOException

java.lang.InterruptedException

write

void write(KEYOUT key,
         VALUEOUT value)
           throws java.io.IOException,
                  java.lang.InterruptedException

Generate an output key/value pair.

Throws:

java.io.IOException

java.lang.InterruptedException

getOutputCommitter

OutputCommitter getOutputCommitter()

Get the OutputCommitter for the task-attempt.

Returns:

the OutputCommitter for the task-attempt