org.apache.hadoop.streaming
Class StreamBaseRecordReader

java.lang.Object
  org.apache.hadoop.streaming.StreamBaseRecordReader

All Implemented Interfaces:

org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Direct Known Subclasses:

StreamXmlRecordReader

public abstract class StreamBaseRecordReader
extends Object
implements org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Shared functionality for hadoopStreaming formats. A custom reader can be defined to be a RecordReader with the constructor below and is selected with the option bin/hadoopStreaming -inputreader ...

See Also:

StreamXmlRecordReader

Field Summary

protected static org.apache.commons.logging.Log

LOG

Constructor Summary

StreamBaseRecordReader(org.apache.hadoop.fs.FSDataInputStream in, org.apache.hadoop.mapred.FileSplit split, org.apache.hadoop.mapred.Reporter reporter, org.apache.hadoop.mapred.JobConf job, org.apache.hadoop.fs.FileSystem fs)

Method Summary

void	close() Close this to future operations.
org.apache.hadoop.io.Text	createKey()
org.apache.hadoop.io.Text	createValue()
long	getPos() Returns the current position in the input.
float	getProgress()
abstract boolean	next(org.apache.hadoop.io.Text key, org.apache.hadoop.io.Text value) Read a record.
abstract void	seekNextRecordBoundary() Implementation should seek forward in_ to the first byte of the next record.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

protected static final org.apache.commons.logging.Log LOG

Constructor Detail

StreamBaseRecordReader

public StreamBaseRecordReader(org.apache.hadoop.fs.FSDataInputStream in,
                              org.apache.hadoop.mapred.FileSplit split,
                              org.apache.hadoop.mapred.Reporter reporter,
                              org.apache.hadoop.mapred.JobConf job,
                              org.apache.hadoop.fs.FileSystem fs)
                       throws IOException

Throws:

IOException

Method Detail

next

public abstract boolean next(org.apache.hadoop.io.Text key,
                             org.apache.hadoop.io.Text value)
                      throws IOException

Read a record. Implementation should call numRecStats at the end

Specified by:

next in interface org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

IOException

getPos

public long getPos()
            throws IOException

Returns the current position in the input.

Specified by:

getPos in interface org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

IOException

close

public void close()
           throws IOException

Close this to future operations.

Specified by:

close in interface org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

IOException

getProgress

public float getProgress()
                  throws IOException

Specified by:

getProgress in interface org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

IOException

createKey

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

Specified by:

createKey in interface org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

createValue

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

Specified by:

createValue in interface org.apache.hadoop.mapred.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

seekNextRecordBoundary

public abstract void seekNextRecordBoundary()
                                     throws IOException

Implementation should seek forward in_ to the first byte of the next record. The initial byte offset in the stream is arbitrary.

Throws:

IOException