Package reactor.core.observability

Class DefaultSignalListener<T>

java.lang.Object

reactor.core.observability.DefaultSignalListener<T>

All Implemented Interfaces:

SignalListener<T>

public abstract class DefaultSignalListener<T>
extends Object
implements SignalListener<T>

A default implementation of a SignalListener with all the handlers no-op.

Author:

Simon Baslé

Constructor Summary

Constructors

Constructor	Description
DefaultSignalListener()

Method Summary

Modifier and Type	Method	Description
void	doAfterComplete()	Handle graceful onComplete sequence termination, after onComplete has been propagated downstream.
void	doAfterError(Throwable error)	Handle onError sequence termination after onError has been propagated downstream.
void	doFinally(SignalType terminationType)	Handle terminal signals after the signals have been propagated, as the final step.
void	doFirst()	Handle the very beginning of the Subscriber-Publisher interaction.
void	doOnCancel()	Handle the downstream cancelling its currently observed Subscription.
void	doOnComplete()	Handle graceful onComplete sequence termination.
void	doOnError(Throwable error)	Handle onError sequence termination.
void	doOnFusion(int negotiatedFusion)	Handle the negotiation of fusion between two Fuseable operators.
void	doOnMalformedOnComplete()	Handle malformed Subscriber.onComplete(), which means the sequence has already terminated via Subscriber.onComplete() or Subscriber.onError(Throwable).
void	doOnMalformedOnError(Throwable error)	Handle malformed Subscriber.onError(Throwable), which means the sequence has already terminated via Subscriber.onComplete() or Subscriber.onError(Throwable).
void	doOnMalformedOnNext(T value)	Handle malformed Subscriber.onNext(Object), which are onNext happening after the sequence has already terminated via Subscriber.onComplete() or Subscriber.onError(Throwable).
void	doOnNext(T value)	Handle a new value emission from the source.
void	doOnRequest(long requested)	Handle a new request made by the downstream, exposing the demand.
void	doOnSubscription()	Handle the fact that the upstream Publisher acknowledged Subscription.
protected int	getFusionMode()	Return the fusion mode negotiated with the source: Fuseable.SYNC and Fuseable.ASYNC) as relevant if some fusion was negotiated.
void	handleListenerError(Throwable listenerError)	A special handler for exceptions thrown from all the other handlers.

Methods inherited from class java.lang.Object

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

Methods inherited from interface reactor.core.observability.SignalListener

addToContext

Constructor Details

DefaultSignalListener

public DefaultSignalListener()

Method Details

doFirst

public void doFirst()
             throws Throwable

Description copied from interface: SignalListener

Handle the very beginning of the Subscriber-Publisher interaction. This handler is invoked right before subscribing to the parent Publisher, as a downstream Subscriber has called Publisher.subscribe(Subscriber).

Once the Publisher has acknowledged with a Subscription, the SignalListener.doOnSubscription() handler will be invoked before that Subscription is passed down.

Specified by:

doFirst in interface SignalListener<T>

Throws:

Throwable

See Also:

• SignalListener.doOnSubscription()

doFinally

public void doFinally(SignalType terminationType)
               throws Throwable

Description copied from interface: SignalListener

Handle terminal signals after the signals have been propagated, as the final step. Only SignalType.ON_COMPLETE, SignalType.ON_ERROR or SignalType.CANCEL can be passed. This handler is invoked AFTER the terminal signal has been propagated, and if relevant AFTER the SignalListener.doAfterComplete() or SignalListener.doAfterError(Throwable) events. If any doOnXxx handler throws, this handler is NOT invoked (see SignalListener.handleListenerError(Throwable) instead).

Specified by:

doFinally in interface SignalListener<T>

Throws:

Throwable

See Also:

• SignalListener.handleListenerError(Throwable)

doOnSubscription

public void doOnSubscription()
                      throws Throwable

Description copied from interface: SignalListener

Handle the fact that the upstream Publisher acknowledged Subscription. The Subscription is intentionally not exposed in order to avoid manipulation by the observer.

While SignalListener.doFirst() is invoked right as the downstream Subscriber is registered, this method is invoked as the upstream answers back with a Subscription (and before that same Subscription is passed downstream).

Specified by:

doOnSubscription in interface SignalListener<T>

Throws:

Throwable

See Also:

• SignalListener.doFirst()

doOnFusion

public void doOnFusion(int negotiatedFusion)
                throws Throwable

Description copied from interface: SignalListener

Handle the negotiation of fusion between two Fuseable operators. As the downstream operator requests fusion, the upstream answers back with the compatible level of fusion it can handle. This negotiatedFusion code is passed to this handler right before it is propagated downstream.

Specified by:

doOnFusion in interface SignalListener<T>

Parameters:

negotiatedFusion - the final fusion mode negotiated by the upstream operator in response to a fusion request from downstream

Throws:

Throwable

getFusionMode

protected int getFusionMode()

Return the fusion mode negotiated with the source: Fuseable.SYNC and Fuseable.ASYNC) as relevant if some fusion was negotiated. Fuseable.NONE if fusion was never requested, or if it couldn't be negotiated.

Returns:

the negotiated fusion mode, if any

doOnRequest

public void doOnRequest(long requested)
                 throws Throwable

Description copied from interface: SignalListener

Handle a new request made by the downstream, exposing the demand.

This is invoked before the request is propagated upstream.

Specified by:

doOnRequest in interface SignalListener<T>

Parameters:

requested - the downstream demand

Throws:

Throwable

doOnCancel

public void doOnCancel()
                throws Throwable

Description copied from interface: SignalListener

Handle the downstream cancelling its currently observed Subscription.

This handler is invoked before propagating the cancellation upstream, while SignalListener.doFinally(SignalType) is invoked right after the cancellation has been propagated upstream.

Specified by:

doOnCancel in interface SignalListener<T>

Throws:

Throwable

See Also:

• SignalListener.doFinally(SignalType)

doOnNext

public void doOnNext(T value)
              throws Throwable

Description copied from interface: SignalListener

Handle a new value emission from the source.

This handler is invoked before propagating the value downstream.

Specified by:

doOnNext in interface SignalListener<T>

Parameters:

value - the emitted value

Throws:

Throwable

doOnComplete

public void doOnComplete()
                  throws Throwable

Description copied from interface: SignalListener

Handle graceful onComplete sequence termination.

This handler is invoked before propagating the completion downstream, while both SignalListener.doAfterComplete() and SignalListener.doFinally(SignalType) are invoked after.

Specified by:

doOnComplete in interface SignalListener<T>

Throws:

Throwable

See Also:

• SignalListener.doAfterComplete()
• SignalListener.doFinally(SignalType)

doOnError

public void doOnError(Throwable error)
               throws Throwable

Description copied from interface: SignalListener

Handle onError sequence termination.

This handler is invoked before propagating the error downstream, while both SignalListener.doAfterError(Throwable) and SignalListener.doFinally(SignalType) are invoked after.

Specified by:

doOnError in interface SignalListener<T>

Parameters:

error - the exception that terminated the sequence

Throws:

Throwable

See Also:

• SignalListener.doAfterError(Throwable)
• SignalListener.doFinally(SignalType)

doAfterComplete

public void doAfterComplete()
                     throws Throwable

Description copied from interface: SignalListener

Handle graceful onComplete sequence termination, after onComplete has been propagated downstream.

This handler is invoked after propagating the completion downstream, similar to SignalListener.doFinally(SignalType) and unlike SignalListener.doOnComplete().

Specified by:

doAfterComplete in interface SignalListener<T>

Throws:

Throwable

doAfterError

public void doAfterError(Throwable error)
                  throws Throwable

Description copied from interface: SignalListener

Handle onError sequence termination after onError has been propagated downstream.

This handler is invoked after propagating the error downstream, similar to SignalListener.doFinally(SignalType) and unlike SignalListener.doOnError(Throwable).

Specified by:

doAfterError in interface SignalListener<T>

Parameters:

error - the exception that terminated the sequence

Throws:

Throwable

doOnMalformedOnNext

public void doOnMalformedOnNext(T value)
                         throws Throwable

Description copied from interface: SignalListener

Handle malformed Subscriber.onNext(Object), which are onNext happening after the sequence has already terminated via Subscriber.onComplete() or Subscriber.onError(Throwable). Note that after this handler is invoked, the value is automatically dropped.

If this handler fails with an exception, that exception is dropped before the value is also dropped.

Specified by:

doOnMalformedOnNext in interface SignalListener<T>

Parameters:

value - the value for which an emission was attempted (which will be automatically dropped afterwards)

Throws:

Throwable

doOnMalformedOnComplete

public void doOnMalformedOnComplete()
                             throws Throwable

Description copied from interface: SignalListener

Handle malformed Subscriber.onComplete(), which means the sequence has already terminated via Subscriber.onComplete() or Subscriber.onError(Throwable).

If this handler fails with an exception, that exception is dropped.

Specified by:

doOnMalformedOnComplete in interface SignalListener<T>

Throws:

Throwable

doOnMalformedOnError

public void doOnMalformedOnError(Throwable error)
                          throws Throwable

Description copied from interface: SignalListener

Handle malformed Subscriber.onError(Throwable), which means the sequence has already terminated via Subscriber.onComplete() or Subscriber.onError(Throwable). Note that after this handler is invoked, the exception is automatically dropped.

If this handler fails with an exception, that exception is dropped before the original onError exception is also dropped.

Specified by:

doOnMalformedOnError in interface SignalListener<T>

Parameters:

error - the extraneous exception (which will be automatically dropped afterwards)

Throws:

Throwable

handleListenerError

public void handleListenerError(Throwable listenerError)

Description copied from interface: SignalListener

A special handler for exceptions thrown from all the other handlers. This method MUST return normally, i.e. it MUST NOT throw. When a SignalListener handler fails, callers are expected to first invoke this method then to propagate the listenerError downstream if that is possible, terminating the original sequence with the listenerError.

Typically, this special handler is intended for a last chance at processing the error despite the fact that SignalListener.doFinally(SignalType) is not triggered on handler errors. For example, recording the error in a metrics backend or cleaning up state that would otherwise be cleaned up by SignalListener.doFinally(SignalType).

Specified by:

handleListenerError in interface SignalListener<T>

Parameters:

listenerError - the exception thrown from a SignalListener handler method