Module io.helidon.common.reactive
Package io.helidon.common.reactive

Class EmittingPublisher<T>

java.lang.Object
io.helidon.common.reactive.EmittingPublisher<T>
Type Parameters:
T - type of emitted item
All Implemented Interfaces:
Flow.Publisher<T>
public class EmittingPublisher<T> extends Object implements Flow.Publisher<T>
Emitting publisher for manual publishing on the same thread. EmittingPublisher doesn't have any buffering capability and propagates backpressure directly by returning false from emit(Object) in case there is no demand, or cancel signal has been received.

For publishing with buffering in case of backpressure use BufferedEmittingPublisher.

This publisher allows only a single subscriber.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    complete()
    Properly complete the stream, set publisher to completed state and send onComplete signal downstream.
    static <T> EmittingPublisher<T>
    create()
    Create new EmittingPublisher.
    boolean
    emit(T item)
    Emit one item to the stream, if there is enough requested and publisher is not cancelled, item is signaled to downstream as onNext and method returns true.
    void
    fail(Throwable throwable)
    Properly fail the stream, set publisher to cancelled state and send onError signal downstream.
    Optional<Throwable>
    failCause()
    Return cause of fail, if publisher is in failed state.
    boolean
    hasRequests()
    Check if demand is higher than 0.
    boolean
    isCancelled()
    Check if publisher has been cancelled.
    boolean
    isCompleted()
    Check if publisher has been completed.
    boolean
    isFailed()
    Check if publisher has been failed.
    boolean
    isUnbounded()
    Check if downstream requested unbounded number of items, eg.
    void
    onCancel(Runnable cancelCallback)
    Executed when cancel signal from downstream arrive.
    void
    onRequest(BiConsumer<Long,Long> requestCallback)
    Callback executed when request signal from downstream arrive.
    void
    subscribe(Flow.Subscriber<? super T> subscriber)
     

    Methods inherited from class java.lang.Object

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

  • Method Details

    • create

      public static <T> EmittingPublisher<T> create()
      Create new EmittingPublisher.
      Type Parameters:
      T - type of emitted item
      Returns:
      brand new EmittingPublisher

    • subscribe

      public void subscribe(Flow.Subscriber<? super T> subscriber)
      Specified by:
      subscribe in interface Flow.Publisher<T>

    • fail

      public void fail(Throwable throwable)
      Properly fail the stream, set publisher to cancelled state and send onError signal downstream. Signal onError is sent only once, any other call to this method is no-op.
      Parameters:
      throwable - Sent as onError signal

    • complete

      public void complete()
      Properly complete the stream, set publisher to completed state and send onComplete signal downstream. Signal onComplete is sent only once, any other call to this method is no-op.

    • emit

      public boolean emit(T item)
      Emit one item to the stream, if there is enough requested and publisher is not cancelled, item is signaled to downstream as onNext and method returns true. If there is requested less than 1, nothing is sent and method returns false.
      Parameters:
      item - to be sent downstream
      Returns:
      true if item successfully sent, false if canceled or no demand
      Throws:
      IllegalStateException - if publisher is completed

    • isCompleted

      public boolean isCompleted()
      Check if publisher has been completed.
      Returns:
      true if so

    • isCancelled

      public boolean isCancelled()
      Check if publisher has been cancelled.
      Returns:
      true if so

    • isFailed

      public boolean isFailed()
      Check if publisher has been failed.
      Returns:
      true if so

    • hasRequests

      public boolean hasRequests()
      Check if demand is higher than 0. Returned value should be used as informative and can change asynchronously.
      Returns:
      true if so

    • isUnbounded

      public boolean isUnbounded()
      Check if downstream requested unbounded number of items, eg. there is no backpressure.
      Returns:
      true if so

    • failCause

      public Optional<Throwable> failCause()
      Return cause of fail, if publisher is in failed state.
      Returns:
      optional cause of fail

    • onCancel

      public void onCancel(Runnable cancelCallback)
      Executed when cancel signal from downstream arrive.
      Parameters:
      cancelCallback - to be executed

    • onRequest

      public void onRequest(BiConsumer<Long,Long> requestCallback)
      Callback executed when request signal from downstream arrive.
      • param n the requested count.
      • param result the current total cumulative requested count, ranges between [0, Long.MAX_VALUE] where the max indicates that this publisher is unbounded.
      Parameters:
      requestCallback - to be executed