Package org.apache.flink.runtime.operators.sort

Class PartialOrderPriorityQueue<T>

java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractQueue<T>
org.apache.flink.runtime.operators.sort.PartialOrderPriorityQueue<T>
All Implemented Interfaces:
Iterable<T>, Collection<T>, Queue<T>
public class PartialOrderPriorityQueue<T> extends AbstractQueue<T> implements Queue<T>
This class implements a priority-queue, which maintains a partial ordering of its elements such that the least element can always be found in constant time. Put()'s and pop()'s require log(size) time.

  • Constructor Details

    • PartialOrderPriorityQueue

      public PartialOrderPriorityQueue(Comparator<T> comparator, int capacity)

  • Method Details

    • remainingCapacity

      public int remainingCapacity()
      Returns the remaining capacity of the backing array.
      Returns:
      The remaining capacity of the backing array.

    • put

      public final void put(T element)
      Adds a buffer to a PriorityQueue in log(size) time. If one tries to add more objects than maxSize from initialize a RuntimeException (ArrayIndexOutOfBound) is thrown.

    • offer

      public boolean offer(T element)
      Adds element to the PriorityQueue in log(size) time if either the PriorityQueue is not full, or not lessThan(element, top()).
      Specified by:
      offer in interface Queue<T>
      Parameters:
      element - The element to insert,
      Returns:
      True, if element is added, false otherwise.

    • peek

      public final T peek()
      Returns the least element of the PriorityQueue in constant time, but does not remove it from the priority queue.
      Specified by:
      peek in interface Queue<T>
      Returns:
      The least element.

    • poll

      public final T poll()
      Removes and returns the least element of the PriorityQueue in log(size) time.
      Specified by:
      poll in interface Queue<T>
      Returns:
      The least element.

    • adjustTop

      public final void adjustTop()
      Should be called when the Object at top changes values. Still log(n) worst case, but it's at least twice as fast to 
       {
        pq.top().change();
        pq.adjustTop();
 }
      instead of 
       {
        o = pq.pop();
        o.change();
        pq.push(o);
 }

    • size

      public final int size()
      Returns the number of elements currently stored in the PriorityQueue.
      Specified by:
      size in interface Collection<T>
      Specified by:
      size in class AbstractCollection<T>
      Returns:
      The number of elements in the queue.

    • clear

      public final void clear()
      Removes all entries from the PriorityQueue.
      Specified by:
      clear in interface Collection<T>
      Overrides:
      clear in class AbstractQueue<T>

    • iterator

      public Iterator<T> iterator()
      Specified by:
      iterator in interface Collection<T>
      Specified by:
      iterator in interface Iterable<T>
      Specified by:
      iterator in class AbstractCollection<T>