org.apache.flink.runtime.operators.sort

Class MergeIterator<E>

java.lang.Object

org.apache.flink.runtime.operators.sort.MergeIterator<E>

All Implemented Interfaces:

MutableObjectIterator<E>

public class MergeIterator<E>
extends Object
implements MutableObjectIterator<E>

An iterator that returns a sorted merge of the sequences of elements from a set of iterators, assuming those sequences are ordered themselves. The iterators to be merged are kept internally as a heap, making each access to the next smallest element logarithmic in complexity, with respect to the number of streams to be merged. The order among the elements is established using the methods from the TypeComparator class, specifically TypeComparator.setReference(Object) and TypeComparator.compareToReference(TypeComparator).

Constructor Summary

Constructors

Constructor and Description
MergeIterator(List<MutableObjectIterator<E>> iterators, TypeComparator<E> comparator)

Method Summary

Modifier and Type	Method and Description
E	next() Gets the next smallest element, with respect to the definition of order implied by the TypeSerializer provided to this iterator.
E	next(E reuse) Gets the next smallest element, with respect to the definition of order implied by the TypeSerializer provided to this iterator.

Methods inherited from class java.lang.Object

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

Constructor Detail

MergeIterator

public MergeIterator(List<MutableObjectIterator<E>> iterators,
                     TypeComparator<E> comparator)
              throws IOException

Parameters:

iterators -

comparator -

Throws:

IOException

Method Detail

next

public E next(E reuse)
       throws IOException

Gets the next smallest element, with respect to the definition of order implied by the TypeSerializer provided to this iterator.

Specified by:

next in interface MutableObjectIterator<E>

Parameters:

reuse - Object that may be reused.

Returns:

The next element if the iterator has another element, null otherwise.

Throws:

IOException - Thrown, if a problem occurred in the underlying I/O layer or in the serialization / deserialization logic

See Also:

MutableObjectIterator.next(java.lang.Object)

next

public E next()
       throws IOException

Gets the next smallest element, with respect to the definition of order implied by the TypeSerializer provided to this iterator.

Specified by:

next in interface MutableObjectIterator<E>

Returns:

The next element if the iterator has another element, null otherwise.

Throws:

IOException - Thrown, if a problem occurred in the underlying I/O layer or in the serialization / deserialization logic

See Also:

MutableObjectIterator.next()