org.apache.hadoop.mapreduce.lib.input
Class FixedLengthRecordReader

java.lang.Object
  org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>
      org.apache.hadoop.mapreduce.lib.input.FixedLengthRecordReader

All Implemented Interfaces:

Closeable

@InterfaceAudience.Private
@InterfaceStability.Evolving
public class FixedLengthRecordReader
extends RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

A reader to read fixed length records from a split. Record offset is returned as key and the record as bytes is returned in value.

Constructor Summary

FixedLengthRecordReader(int recordLength)

Method Summary

void	close() Close the record reader.
org.apache.hadoop.io.LongWritable	getCurrentKey() Get the current key
org.apache.hadoop.io.BytesWritable	getCurrentValue() Get the current value.
long	getPos()
float	getProgress() The current progress of the record reader through its data.
void	initialize(org.apache.hadoop.conf.Configuration job, long splitStart, long splitLength, org.apache.hadoop.fs.Path file)
void	initialize(InputSplit genericSplit, TaskAttemptContext context) Called once at initialization.
boolean	nextKeyValue() Read the next key, value pair.

Methods inherited from class java.lang.Object

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

Constructor Detail

FixedLengthRecordReader

public FixedLengthRecordReader(int recordLength)

Method Detail

initialize

public void initialize(InputSplit genericSplit,
                       TaskAttemptContext context)
                throws IOException

Description copied from class: RecordReader

Called once at initialization.

Specified by:

initialize in class RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Parameters:

genericSplit - the split that defines the range of records to read

context - the information about the task

Throws:

IOException

initialize

public void initialize(org.apache.hadoop.conf.Configuration job,
                       long splitStart,
                       long splitLength,
                       org.apache.hadoop.fs.Path file)
                throws IOException

Throws:

IOException

nextKeyValue

public boolean nextKeyValue()
                     throws IOException

Description copied from class: RecordReader

Read the next key, value pair.

Specified by:

nextKeyValue in class RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Returns:

true if a key/value pair was read

Throws:

IOException

getCurrentKey

public org.apache.hadoop.io.LongWritable getCurrentKey()

Description copied from class: RecordReader

Get the current key

Specified by:

getCurrentKey in class RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Returns:

the current key or null if there is no current key

getCurrentValue

public org.apache.hadoop.io.BytesWritable getCurrentValue()

Description copied from class: RecordReader

Get the current value.

Specified by:

getCurrentValue in class RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Returns:

the object that was read

getProgress

public float getProgress()
                  throws IOException

Description copied from class: RecordReader

The current progress of the record reader through its data.

Specified by:

getProgress in class RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Returns:

a number between 0.0 and 1.0 that is the fraction of the data read

Throws:

IOException

close

public void close()
           throws IOException

Description copied from class: RecordReader

Close the record reader.

Specified by:

close in interface Closeable

Specified by:

close in class RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Throws:

IOException

getPos

public long getPos()