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

Class OrderedStreamElementQueue<OUT>

  • All Implemented Interfaces:
    StreamElementQueue<OUT>
    @Internal
public final class OrderedStreamElementQueue<OUT>
extends Object
implements StreamElementQueue<OUT>
    Ordered StreamElementQueue implementation. The ordered stream element queue provides asynchronous results in the order in which the StreamElementQueueEntry have been added to the queue. Thus, even if the completion order can be arbitrary, the output order strictly follows the insertion order (element cannot overtake each other).

    • Constructor Detail

      • OrderedStreamElementQueue

        public OrderedStreamElementQueue​(int capacity)

    • Method Detail

      • 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.

      • 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.