io.reactivex.rxjava3.core

Interface FlowableEmitter<T>

Type Parameters:

T - the value type to emit

All Superinterfaces:

Emitter<T>

public interface FlowableEmitter<T>
extends Emitter<T>

Abstraction over a Reactive Streams Subscriber that allows associating a resource with it and exposes the current number of downstream requested amount.

The Emitter.onNext(Object), Emitter.onError(Throwable), tryOnError(Throwable) and Emitter.onComplete() methods should be called in a sequential manner, just like the Subscriber's methods. Use the FlowableEmitter the serialize() method returns instead of the original FlowableEmitter instance provided by the generator routine if you want to ensure this. The other methods are thread-safe.

The emitter allows the registration of a single resource, in the form of a Disposable or Cancellable via setDisposable(Disposable) or setCancellable(Cancellable) respectively. The emitter implementations will dispose/cancel this instance when the downstream cancels the flow or after the event generator logic calls Emitter.onError(Throwable), Emitter.onComplete() or when tryOnError(Throwable) succeeds.

Only one Disposable or Cancellable object can be associated with the emitter at a time. Calling either set method will dispose/cancel any previous object. If there is a need for handling multiple resources, one can create a CompositeDisposable and associate that with the emitter instead.

The Cancellable is logically equivalent to Disposable but allows using cleanup logic that can throw a checked exception (such as many close() methods on Java IO components). Since the release of resources happens after the terminal events have been delivered or the sequence gets cancelled, exceptions throw within Cancellable are routed to the global error handler via RxJavaPlugins.onError(Throwable).

Method Summary

Modifier and Type	Method and Description
boolean	isCancelled() Returns true if the downstream cancelled the sequence or the emitter was terminated via Emitter.onError(Throwable), Emitter.onComplete() or a successful tryOnError(Throwable).
long	requested() The current outstanding request amount.
@NonNull FlowableEmitter<T>	serialize() Ensures that calls to onNext, onError and onComplete are properly serialized.
void	setCancellable(@Nullable Cancellable c) Sets a Cancellable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.
void	setDisposable(@Nullable Disposable d) Sets a Disposable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.
boolean	tryOnError(@NonNull Throwable t) Attempts to emit the specified Throwable error if the downstream hasn't cancelled the sequence or is otherwise terminated, returning false if the emission is not allowed to happen due to lifecycle restrictions.

Methods inherited from interface io.reactivex.rxjava3.core.Emitter

onComplete, onError, onNext

Method Detail

setDisposable

void setDisposable(@Nullable
                   @Nullable Disposable d)

Sets a Disposable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.

This method is thread-safe.

Parameters:

d - the disposable, null is allowed

setCancellable

void setCancellable(@Nullable
                    @Nullable Cancellable c)

Sets a Cancellable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.

This method is thread-safe.

Parameters:

c - the Cancellable resource, null is allowed

requested

long requested()

The current outstanding request amount.

This method is thread-safe.

Returns:

the current outstanding request amount

isCancelled

boolean isCancelled()

Returns true if the downstream cancelled the sequence or the emitter was terminated via Emitter.onError(Throwable), Emitter.onComplete() or a successful tryOnError(Throwable).

This method is thread-safe.

Returns:

true if the downstream cancelled the sequence or the emitter was terminated

serialize

@NonNull
@NonNull FlowableEmitter<T> serialize()

Ensures that calls to onNext, onError and onComplete are properly serialized.

Returns:

the serialized FlowableEmitter

tryOnError

boolean tryOnError(@NonNull
                   @NonNull Throwable t)

Attempts to emit the specified Throwable error if the downstream hasn't cancelled the sequence or is otherwise terminated, returning false if the emission is not allowed to happen due to lifecycle restrictions.

Unlike Emitter.onError(Throwable), the RxjavaPlugins.onError is not called if the error could not be delivered.

History: 2.1.1 - experimental

Parameters:

t - the throwable error to signal if possible

Returns:

true if successful, false if the downstream is not able to accept further events

Since:

2.2