Package org.apache.hadoop.mapred.lib

Class CombineFileRecordReaderWrapper<K,V>

java.lang.Object

org.apache.hadoop.mapred.lib.CombineFileRecordReaderWrapper<K,V>

All Implemented Interfaces:

Closeable, AutoCloseable, RecordReader<K,V>

@Public
@Stable
public abstract class CombineFileRecordReaderWrapper<K,V>
extends Object
implements RecordReader<K,V>

A wrapper class for a record reader that handles a single file split. It delegates most of the methods to the wrapped instance. A concrete subclass needs to provide a constructor that calls this parent constructor with the appropriate input format. The subclass constructor must satisfy the specific constructor signature that is required by CombineFileRecordReader. Subclassing is needed to get a concrete record reader wrapper because of the constructor requirement.

See Also:

• CombineFileRecordReader
• CombineFileInputFormat

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	CombineFileRecordReaderWrapper(FileInputFormat<K,V> inputFormat, CombineFileSplit split, Configuration conf, Reporter reporter, Integer idx)

Method Summary

Modifier and Type	Method	Description
void	close()	Close this InputSplit to future operations.
K	createKey()	Create an object of the appropriate type to be used as a key.
V	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(K key, V 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 Details

CombineFileRecordReaderWrapper

protected CombineFileRecordReaderWrapper(FileInputFormat<K,V> inputFormat,
 CombineFileSplit split,
 Configuration conf,
 Reporter reporter,
 Integer idx)
                                  throws IOException

Throws:

IOException

Method Details

next

public boolean next(K key,
 V 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<K,V>

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

createKey

public K 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<K,V>

Returns:

a new key object.

createValue

public V 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<K,V>

Returns:

a new value object.

getPos

public long getPos()
            throws IOException

Description copied from interface: RecordReader

Returns the current position in the input.

Specified by:

getPos in interface RecordReader<K,V>

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 AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface RecordReader<K,V>

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<K,V>

Returns:

progress from 0.0 to 1.0.

Throws:

IOException