Package reactor.core.observability

Interface SignalListenerFactory<T,STATE>

Type Parameters:

T - the type of data emitted by the observed source Publisher

STATE - the type of the publisher-level state that will be shared between all SignalListener created by this factory

public interface SignalListenerFactory<T,STATE>

A factory for per-subscription SignalListener, exposing the ability to generate common state at publisher level from the source Publisher.

Examples of such state include:

• is the publisher a Mono? (unlocking Mono-specific behavior in the SignalListener
• resolution of NAME and TAGS on the source
• preparation of a common configuration, like a registry for metrics

Author:

Simon Baslé

Method Summary

Modifier and Type	Method	Description
SignalListener<T>	createListener(Publisher<? extends T> source, ContextView listenerContext, STATE publisherContext)	Create a new SignalListener each time a new Subscriber subscribes to the source Publisher.
STATE	initializePublisherState(Publisher<? extends T> source)	Create the STATE object for the given Publisher.

Method Details

initializePublisherState

STATE initializePublisherState(Publisher<? extends T> source)

Create the STATE object for the given Publisher. This assumes this factory will only be used on that particular source, allowing all SignalListener created by this factory to inherit the common state.

Parameters:

source - the source Publisher this factory is attached to.

Returns:

the common state

createListener

SignalListener<T> createListener(Publisher<? extends T> source,
 ContextView listenerContext,
 STATE publisherContext)

Create a new SignalListener each time a new Subscriber subscribes to the source Publisher.

The source Publisher is the same as the one that triggered common state creation at assembly time in initializePublisherState(Publisher)). Said common state is passed to this method as well, and so is the ContextView for the newly registered CoreSubscriber.

Parameters:

source - the source Publisher that is being subscribed to

listenerContext - the ContextView associated with the new subscriber

publisherContext - the common state initialized in initializePublisherState(Publisher)

Returns:

a stateful SignalListener observing signals to and from the new subscriber