org.apache.hadoop.mapreduce.lib.input
Class KeyValueLineRecordReader

java.lang.Object
  org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>
      org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader

All Implemented Interfaces:

Closeable

@InterfaceAudience.Public
@InterfaceStability.Stable
public class KeyValueLineRecordReader
extends RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

This class treats a line in the input as a key/value pair separated by a separator character. The separator can be specified in config file under the attribute name mapreduce.input.keyvaluelinerecordreader.key.value.separator. The default separator is the tab character ('\t').

Field Summary

static String

KEY_VALUE_SEPERATOR

Constructor Summary

KeyValueLineRecordReader(org.apache.hadoop.conf.Configuration conf)

Method Summary

void	close() Close the record reader.
static int	findSeparator(byte[] utf, int start, int length, byte sep)
org.apache.hadoop.io.Text	getCurrentKey() Get the current key
org.apache.hadoop.io.Text	getCurrentValue() Get the current value.
Class	getKeyClass()
float	getProgress() The current progress of the record reader through its data.
void	initialize(InputSplit genericSplit, TaskAttemptContext context) Called once at initialization.
boolean	nextKeyValue() Read key/value pair in a line.
static void	setKeyValue(org.apache.hadoop.io.Text key, org.apache.hadoop.io.Text value, byte[] line, int lineLen, int pos)

Methods inherited from class java.lang.Object

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

Field Detail

KEY_VALUE_SEPERATOR

public static final String KEY_VALUE_SEPERATOR

See Also:

Constant Field Values

Constructor Detail

KeyValueLineRecordReader

public KeyValueLineRecordReader(org.apache.hadoop.conf.Configuration conf)
                         throws IOException

Throws:

IOException

Method Detail

getKeyClass

public Class getKeyClass()

initialize

public void initialize(InputSplit genericSplit,
                       TaskAttemptContext context)
                throws IOException

Description copied from class: RecordReader

Called once at initialization.

Specified by:

initialize in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Parameters:

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

context - the information about the task

Throws:

IOException

findSeparator

public static int findSeparator(byte[] utf,
                                int start,
                                int length,
                                byte sep)

setKeyValue

public static void setKeyValue(org.apache.hadoop.io.Text key,
                               org.apache.hadoop.io.Text value,
                               byte[] line,
                               int lineLen,
                               int pos)

nextKeyValue

public boolean nextKeyValue()
                     throws IOException

Read key/value pair in a line.

Specified by:

nextKeyValue in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

true if a key/value pair was read

Throws:

IOException

getCurrentKey

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

Description copied from class: RecordReader

Get the current key

Specified by:

getCurrentKey in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

the current key or null if there is no current key

getCurrentValue

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

Description copied from class: RecordReader

Get the current value.

Specified by:

getCurrentValue in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

the object that was read

getProgress

public float getProgress()
                  throws IOException

Description copied from class: RecordReader

The current progress of the record reader through its data.

Specified by:

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

Returns:

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

Throws:

IOException

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

Throws:

IOException