Class QueuedProducer<T>

Type Parameters:
T - the value type
All Implemented Interfaces:
Serializable, Observer<T>, Producer

public final class QueuedProducer<T> extends AtomicLong implements Producer, Observer<T>
Producer that holds an unbounded (or custom) queue, handles terminal events, enqueues values and relays them to a child subscriber on request.
See Also:
  • Field Details

  • Constructor Details

    • QueuedProducer

      public QueuedProducer(Subscriber<? super T> child)
      Constructs an instance with the target child subscriber and an Spsc Linked (Atomic) Queue as the queue implementation.
      Parameters:
      child - the target child subscriber
    • QueuedProducer

      public QueuedProducer(Subscriber<? super T> child, Queue<Object> queue)
      Constructs an instance with the target child subscriber and a custom queue implementation
      Parameters:
      child - the target child subscriber
      queue - the queue to use
  • Method Details

    • request

      public void request(long n)
      Description copied from interface: Producer
      Request a certain maximum number of items from this Producer. This is a way of requesting backpressure. To disable backpressure, pass Long.MAX_VALUE to this method.

      Requests are additive but if a sequence of requests totals more than Long.MAX_VALUE then Long.MAX_VALUE requests will be actioned and the extras may be ignored. Arriving at Long.MAX_VALUE by addition of requests cannot be assumed to disable backpressure. For example, the code below may result in Long.MAX_VALUE requests being actioned only.

       request(100);
       request(Long.MAX_VALUE-1);
       
      Specified by:
      request in interface Producer
      Parameters:
      n - the maximum number of items you want this Producer to produce, or Long.MAX_VALUE if you want the Producer to produce items at its own pace
    • offer

      public boolean offer(T value)
      Offers a value to this producer and tries to emit any queued values if the child requests allow it.
      Parameters:
      value - the value to enqueue and attempt to drain
      Returns:
      true if the queue accepted the offer, false otherwise
    • onNext

      public void onNext(T value)
      Description copied from interface: Observer
      Provides the Observer with a new item to observe.

      The Observable may call this method 0 or more times.

      The Observable will not call this method again after it calls either Observer.onCompleted() or Observer.onError(java.lang.Throwable).

      Specified by:
      onNext in interface Observer<T>
      Parameters:
      value - the item emitted by the Observable
    • onError

      public void onError(Throwable e)
      Description copied from interface: Observer
      Notifies the Observer that the Observable has experienced an error condition.

      If the Observable calls this method, it will not thereafter call Observer.onNext(T) or Observer.onCompleted().

      Specified by:
      onError in interface Observer<T>
      Parameters:
      e - the exception encountered by the Observable
    • onCompleted

      public void onCompleted()
      Description copied from interface: Observer
      Notifies the Observer that the Observable has finished sending push-based notifications.

      The Observable will not call this method if it calls Observer.onError(java.lang.Throwable).

      Specified by:
      onCompleted in interface Observer<T>
    • checkTerminated

      private boolean checkTerminated(boolean isDone, boolean isEmpty)
    • drain

      private void drain()