io.cdap.cdap.api.data.batch

Class IteratorBasedSplitReader<KEY,VALUE>

java.lang.Object

io.cdap.cdap.api.data.batch.SplitReader<KEY,VALUE>

io.cdap.cdap.api.data.batch.SplitReaderBase<KEY,VALUE>

io.cdap.cdap.api.data.batch.IteratorBasedSplitReader<KEY,VALUE>

Type Parameters:

KEY - The key type.

VALUE - The value type.

Direct Known Subclasses:

TimeseriesTable.TimeseriesTableRecordsReader

public abstract class IteratorBasedSplitReader<KEY,VALUE>
extends SplitReaderBase<KEY,VALUE>

Handy implementation of SplitReader backed by Iterator.

Constructor Summary

Constructors

Constructor and Description
IteratorBasedSplitReader()

Method Summary

Modifier and Type	Method and Description
protected abstract Iterator<VALUE>	createIterator(Split split) Creates an iterator to iterate through all records of a given split.
protected boolean	fetchNextKeyValue() Fetches the next data item of the split being read.
protected abstract KEY	getKey(VALUE value) Gets the key belonging to the key/value record provided by the iterator.
void	initialize(Split split) Called once at initialization.

Methods inherited from class io.cdap.cdap.api.data.batch.SplitReaderBase

close, getCurrentKey, getCurrentValue, nextKeyValue, setCurrentKeyValue

Methods inherited from class io.cdap.cdap.api.data.batch.SplitReader

getProgress

Methods inherited from class java.lang.Object

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

Constructor Detail

IteratorBasedSplitReader

public IteratorBasedSplitReader()

Method Detail

createIterator

protected abstract Iterator<VALUE> createIterator(Split split)

Creates an iterator to iterate through all records of a given split.

Parameters:

split - Split to iterate through.

Returns:

An instance of Iterator.

getKey

protected abstract KEY getKey(VALUE value)

Gets the key belonging to the key/value record provided by the iterator.

Parameters:

value - The value of the key/value record.

Returns:

The key of the key/value record.

initialize

public void initialize(Split split)
                throws InterruptedException

Description copied from class: SplitReader

Called once at initialization.

Specified by:

initialize in class SplitReader<KEY,VALUE>

Parameters:

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

Throws:

InterruptedException

fetchNextKeyValue

protected boolean fetchNextKeyValue()

Description copied from class: SplitReaderBase

Fetches the next data item of the split being read. If true, use the SplitReaderBase.setCurrentKeyValue(Object, Object) method to set the new current key/value. If false there are no more key/value records to read. See IteratorBasedSplitReader for an implementation of the abstract fetchNextKeyValue() method.

Specified by:

fetchNextKeyValue in class SplitReaderBase<KEY,VALUE>

Returns:

false if reached end of the split, true otherwise.