Package org.apache.flink.streaming.api.operators.async.queue

Class UnorderedStreamElementQueue<OUT>

  • All Implemented Interfaces:
    StreamElementQueue<OUT>
    @Internal
public final class UnorderedStreamElementQueue<OUT>
extends Object
implements StreamElementQueue<OUT>
    Unordered implementation of the StreamElementQueue. The unordered stream element queue provides asynchronous results as soon as they are completed. Additionally, it maintains the watermark-stream record order.

    Elements can be logically grouped into different segments separated by watermarks. A segment needs to be completely emitted before entries from a following segment are emitted. Thus, no stream record can be overtaken by a watermark and no watermark can overtake a stream record. However, stream records falling in the same segment between two watermarks can overtake each other (their emission order is not guaranteed).

    • Constructor Detail

      • UnorderedStreamElementQueue

        public UnorderedStreamElementQueue​(int capacity)

    • Method Detail

      • tryPut

        public Optional<ResultFuture<OUT>> tryPut​(org.apache.flink.streaming.runtime.streamrecord.StreamElement streamElement)
        Description copied from interface: StreamElementQueue
        Tries to put the given element in the queue. This operation succeeds if the queue has capacity left and fails if the queue is full.

        This method returns a handle to the inserted element that allows to set the result of the computation.

        Specified by:
        tryPut in interface StreamElementQueue<OUT>
        Parameters:
        streamElement - the element to be inserted.
        Returns:
        A handle to the element if successful or Optional.empty() otherwise.

      • hasCompletedElements

        public boolean hasCompletedElements()
        Description copied from interface: StreamElementQueue
        Checks if there is at least one completed head element.
        Specified by:
        hasCompletedElements in interface StreamElementQueue<OUT>
        Returns:
        True if there is a completed head element.

      • emitCompletedElement

        public void emitCompletedElement​(org.apache.flink.streaming.api.operators.TimestampedCollector<OUT> output)
        Description copied from interface: StreamElementQueue
        Emits one completed element from the head of this queue into the given output.

        Will not emit any element if no element has been completed (check StreamElementQueue.hasCompletedElements() before entering any critical section).

        Specified by:
        emitCompletedElement in interface StreamElementQueue<OUT>
        Parameters:
        output - the output into which to emit

      • values

        public List<org.apache.flink.streaming.runtime.streamrecord.StreamElement> values()
        Description copied from interface: StreamElementQueue
        Returns the collection of StreamElement currently contained in this queue for checkpointing.

        This includes all non-emitted, completed and non-completed elements.

        Specified by:
        values in interface StreamElementQueue<OUT>
        Returns:
        List of currently contained StreamElement.

      • isEmpty

        public boolean isEmpty()
        Description copied from interface: StreamElementQueue
        True if the queue is empty; otherwise false.
        Specified by:
        isEmpty in interface StreamElementQueue<OUT>
        Returns:
        True if the queue is empty; otherwise false.

      • size

        public int size()
        Description copied from interface: StreamElementQueue
        Return the size of the queue.
        Specified by:
        size in interface StreamElementQueue<OUT>
        Returns:
        The number of elements contained in this queue.