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

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

Method Summary

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