Package org.apache.flink.runtime.state.heap

Class HeapPriorityQueue<T extends HeapPriorityQueueElement>

java.lang.Object

org.apache.flink.runtime.state.heap.AbstractHeapPriorityQueue<T>

org.apache.flink.runtime.state.heap.HeapPriorityQueue<T>

Type Parameters:

T - type of the contained elements.

All Implemented Interfaces:

InternalPriorityQueue<T>

Direct Known Subclasses:

HeapPriorityQueueSet

public class HeapPriorityQueue<T extends HeapPriorityQueueElement>
extends AbstractHeapPriorityQueue<T>

Basic heap-based priority queue for HeapPriorityQueueElement objects. This heap supports fast deletes because it manages position indexes of the contained HeapPriorityQueueElements. The heap implementation is a simple binary tree stored inside an array. Element indexes in the heap array start at 1 instead of 0 to make array index computations a bit simpler in the hot methods. Object identification of remove is based on object identity and not on equals. We use the managed index from HeapPriorityQueueElement to find an element in the queue array to support fast deletes.

Possible future improvements:

• We could also implement shrinking for the heap.

Field Summary

Fields

Modifier and Type	Field	Description
protected final PriorityComparator<T>	elementPriorityComparator	Comparator for the priority of contained elements.

Fields inherited from class org.apache.flink.runtime.state.heap.AbstractHeapPriorityQueue

queue, size

Constructor Summary

Constructors

Constructor	Description
HeapPriorityQueue(PriorityComparator<T> elementPriorityComparator, int minimumCapacity)	Creates an empty HeapPriorityQueue with the requested initial capacity.

Method Summary

Modifier and Type	Method	Description
protected void	addInternal(T element)	Implements how to add an element to the queue.
void	adjustModifiedElement(T element)
protected int	getHeadElementIndex()	Returns the start index of the queue elements in the array.
protected T	removeInternal(int removeIdx)	Implements how to remove the element at the given index from the queue.

Methods inherited from class org.apache.flink.runtime.state.heap.AbstractHeapPriorityQueue

add, addAll, clear, isEmpty, iterator, moveElementToIdx, peek, poll, remove, resizeForBulkLoad, resizeQueueArray, size, toArray

Methods inherited from class java.lang.Object

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

Field Details

elementPriorityComparator

@Nonnull
protected final PriorityComparator<T extends HeapPriorityQueueElement> elementPriorityComparator

Comparator for the priority of contained elements.

Constructor Details

HeapPriorityQueue

public HeapPriorityQueue(@Nonnull
 PriorityComparator<T> elementPriorityComparator,
 @Nonnegative
 int minimumCapacity)

Creates an empty HeapPriorityQueue with the requested initial capacity.

Parameters:

elementPriorityComparator - comparator for the priority of contained elements.

minimumCapacity - the minimum and initial capacity of this priority queue.

Method Details

adjustModifiedElement

public void adjustModifiedElement(@Nonnull
 T element)

getHeadElementIndex

protected int getHeadElementIndex()

Description copied from class: AbstractHeapPriorityQueue

Returns the start index of the queue elements in the array.

Specified by:

getHeadElementIndex in class AbstractHeapPriorityQueue<T extends HeapPriorityQueueElement>

addInternal

protected void addInternal(@Nonnull
 T element)

Description copied from class: AbstractHeapPriorityQueue

Implements how to add an element to the queue.

Specified by:

addInternal in class AbstractHeapPriorityQueue<T extends HeapPriorityQueueElement>

Parameters:

element - the element to add.

removeInternal

protected T removeInternal(int removeIdx)

Description copied from class: AbstractHeapPriorityQueue

Implements how to remove the element at the given index from the queue.

Specified by:

removeInternal in class AbstractHeapPriorityQueue<T extends HeapPriorityQueueElement>

Parameters:

removeIdx - the index to remove.

Returns:

the removed element.