org.apache.hadoop.mapreduce.lib.input

Class CombineFileRecordReaderWrapper<K,V>

java.lang.Object

org.apache.hadoop.mapreduce.RecordReader<K,V>

org.apache.hadoop.mapreduce.lib.input.CombineFileRecordReaderWrapper<K,V>

All Implemented Interfaces:

Closeable, AutoCloseable

@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class CombineFileRecordReaderWrapper<K,V>
extends 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 and Description
protected	CombineFileRecordReaderWrapper(FileInputFormat<K,V> inputFormat, CombineFileSplit split, TaskAttemptContext context, Integer idx)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close the record reader.
K	getCurrentKey() Get the current key
V	getCurrentValue() Get the current value.
float	getProgress() The current progress of the record reader through its data.
void	initialize(InputSplit split, 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

CombineFileRecordReaderWrapper

protected CombineFileRecordReaderWrapper(FileInputFormat<K,V> inputFormat,
                              CombineFileSplit split,
                              TaskAttemptContext context,
                              Integer idx)
                                  throws IOException,
                                         InterruptedException

Throws:

IOException

InterruptedException

Method Detail

initialize

public void initialize(InputSplit split,
              TaskAttemptContext context)
                throws IOException,
                       InterruptedException

Description copied from class: RecordReader

Called once at initialization.

Specified by:

initialize in class RecordReader<K,V>

Parameters:

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

context - the information about the task

Throws:

IOException

InterruptedException

nextKeyValue

public boolean nextKeyValue()
                     throws IOException,
                            InterruptedException

Description copied from class: RecordReader

Read the next key, value pair.

Specified by:

nextKeyValue in class RecordReader<K,V>

Returns:

true if a key/value pair was read

Throws:

IOException

InterruptedException

getCurrentKey

public K getCurrentKey()
                throws IOException,
                       InterruptedException

Description copied from class: RecordReader

Get the current key

Specified by:

getCurrentKey in class RecordReader<K,V>

Returns:

the current key or null if there is no current key

Throws:

IOException

InterruptedException

getCurrentValue

public V getCurrentValue()
                  throws IOException,
                         InterruptedException

Description copied from class: RecordReader

Get the current value.

Specified by:

getCurrentValue in class RecordReader<K,V>

Returns:

the object that was read

Throws:

IOException

InterruptedException

getProgress

public float getProgress()
                  throws IOException,
                         InterruptedException

Description copied from class: RecordReader

The current progress of the record reader through its data.

Specified by:

getProgress in class RecordReader<K,V>

Returns:

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

Throws:

IOException

InterruptedException

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 interface AutoCloseable

Specified by:

close in class RecordReader<K,V>

Throws:

IOException