org.apache.hadoop.mapred

Class FixedLengthRecordReader

java.lang.Object

org.apache.hadoop.mapred.FixedLengthRecordReader

All Implemented Interfaces:

RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

@InterfaceAudience.Private
@InterfaceStability.Evolving
public class FixedLengthRecordReader
extends Object
implements 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

Constructors

Constructor and Description
FixedLengthRecordReader(org.apache.hadoop.conf.Configuration job, FileSplit split, int recordLength)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close this InputSplit to future operations.
org.apache.hadoop.io.LongWritable	createKey() Create an object of the appropriate type to be used as a key.
org.apache.hadoop.io.BytesWritable	createValue() Create an object of the appropriate type to be used as a value.
long	getPos() Returns the current position in the input.
float	getProgress() How much of the input has the RecordReader consumed i.e.
boolean	next(org.apache.hadoop.io.LongWritable key, org.apache.hadoop.io.BytesWritable value) Reads the next key/value pair from the input for processing.

Methods inherited from class java.lang.Object

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

Constructor Detail

FixedLengthRecordReader

public FixedLengthRecordReader(org.apache.hadoop.conf.Configuration job,
                       FileSplit split,
                       int recordLength)
                        throws IOException

Throws:

IOException

Method Detail

createKey

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

Description copied from interface: RecordReader

Create an object of the appropriate type to be used as a key.

Specified by:

createKey in interface RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Returns:

a new key object.

createValue

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

Description copied from interface: RecordReader

Create an object of the appropriate type to be used as a value.

Specified by:

createValue in interface RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Returns:

a new value object.

next

public boolean next(org.apache.hadoop.io.LongWritable key,
           org.apache.hadoop.io.BytesWritable value)
             throws IOException

Description copied from interface: RecordReader

Reads the next key/value pair from the input for processing.

Specified by:

next in interface RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Parameters:

key - the key to read data into

value - the value to read data into

Returns:

true iff a key/value was read, false if at EOF

Throws:

IOException

getProgress

public float getProgress()
                  throws IOException

Description copied from interface: RecordReader

How much of the input has the RecordReader consumed i.e. has been processed by?

Specified by:

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

Returns:

progress from 0.0 to 1.0.

Throws:

IOException

getPos

public long getPos()
            throws IOException

Description copied from interface: RecordReader

Returns the current position in the input.

Specified by:

getPos in interface RecordReader<org.apache.hadoop.io.LongWritable,org.apache.hadoop.io.BytesWritable>

Returns:

the current position in the input.

Throws:

IOException

close

public void close()
           throws IOException

Description copied from interface: RecordReader

Close this InputSplit to future operations.

Specified by:

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

Throws:

IOException