Package org.apache.pekko.stream.javadsl

Class MergeHub

java.lang.Object

org.apache.pekko.stream.javadsl.MergeHub

public class MergeHub
extends Object

A MergeHub is a special streaming hub that is able to collect streamed elements from a dynamic set of producers. It consists of two parts, a Source and a Sink. The Source streams the element to a consumer from its merged inputs. Once the consumer has been materialized, the Source returns a materialized value which is the corresponding Sink. This Sink can then be materialized arbitrary many times, where each of the new materializations will feed its consumed elements to the original Source.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	MergeHub.DrainingControl	A DrainingControl object is created during the materialization of a MergeHub and allows to initiate the draining and eventual completion of the Hub from the outside.

Constructor Summary

Constructors

Constructor	Description
MergeHub()

Method Summary

Modifier and Type	Method	Description
static <T> Source<T,Sink<T,NotUsed>>	of(Class<T> clazz)	Creates a Source that emits elements merged from a dynamic set of producers.
static <T> Source<T,Sink<T,NotUsed>>	of(Class<T> clazz, int perProducerBufferSize)	Creates a Source that emits elements merged from a dynamic set of producers.
static <T> Source<T,Pair<Sink<T,NotUsed>,MergeHub.DrainingControl>>	withDraining(Class<T> clazz)	Creates a Source that emits elements merged from a dynamic set of producers.
static <T> Source<T,Pair<Sink<T,NotUsed>,MergeHub.DrainingControl>>	withDraining(Class<T> clazz, int perProducerBufferSize)	Creates a Source that emits elements merged from a dynamic set of producers.

Methods inherited from class java.lang.Object

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

Constructor Details

MergeHub

public MergeHub()

Method Details

of

public static <T> Source<T,Sink<T,NotUsed>> of(Class<T> clazz,
 int perProducerBufferSize)

Creates a Source that emits elements merged from a dynamic set of producers. After the Source returned by this method is materialized, it returns a Sink as a materialized value. This Sink can be materialized arbitrary many times and each of the materializations will feed the elements into the original Source.

Every new materialization of the Source results in a new, independent hub, which materializes to its own Sink for feeding that materialization.

Completed or failed Sinks are simply removed. Once the Source is cancelled, the Hub is considered closed and any new producers using the Sink will be cancelled.

Parameters:

clazz - Type of elements this hub emits and consumes

perProducerBufferSize - Buffer space used per producer.

withDraining

public static <T>
Source<T,Pair<Sink<T,NotUsed>,MergeHub.DrainingControl>> withDraining(Class<T> clazz,
 int perProducerBufferSize)

Creates a Source that emits elements merged from a dynamic set of producers. After the Source returned by this method is materialized, it returns a Sink as a materialized value. This Sink can be materialized arbitrarily many times and each of the materializations will feed the elements into the original Source.

Every new materialization of the Source results in a new, independent hub, which materializes to its own Sink for feeding that materialization.

Completed or failed Sinks are simply removed. Once the Source is cancelled, the Hub is considered closed and any new producers using the Sink will be cancelled.

The materialized MergeHub.DrainingControl can be used to drain the Hub: any new produces using the Sink will be cancelled and the Hub will be closed completing the Source as soon as all currently connected producers complete.

Parameters:

clazz - Type of elements this hub emits and consumes

perProducerBufferSize - Buffer space used per producer. Default value is 16.

of

public static <T> Source<T,Sink<T,NotUsed>> of(Class<T> clazz)

Creates a Source that emits elements merged from a dynamic set of producers. After the Source returned by this method is materialized, it returns a Sink as a materialized value. This Sink can be materialized arbitrary many times and each of the materializations will feed the elements into the original Source.

Every new materialization of the Source results in a new, independent hub, which materializes to its own Sink for feeding that materialization.

Completed or failed Sinks are simply removed. Once the Source is cancelled, the Hub is considered closed and any new producers using the Sink will be cancelled.

Parameters:

clazz - Type of elements this hub emits and consumes

withDraining

public static <T>
Source<T,Pair<Sink<T,NotUsed>,MergeHub.DrainingControl>> withDraining(Class<T> clazz)

Creates a Source that emits elements merged from a dynamic set of producers. After the Source returned by this method is materialized, it returns a Sink as a materialized value. This Sink can be materialized arbitrarily many times and each of the materializations will feed the elements into the original Source.

Every new materialization of the Source results in a new, independent hub, which materializes to its own Sink for feeding that materialization.

Completed or failed Sinks are simply removed. Once the Source is cancelled, the Hub is considered closed and any new producers using the Sink will be cancelled.

The materialized MergeHub.DrainingControl can be used to drain the Hub: any new produces using the Sink will be cancelled and the Hub will be closed completing the Source as soon as all currently connected producers complete.

Parameters:

clazz - Type of elements this hub emits and consumes