io.servicetalk.concurrent.api

Interface PublisherProcessorSignalsHolder<T>

Type Parameters:

T - Type of items stored in this holder.

public interface PublisherProcessorSignalsHolder<T>

A holder of items for a PublisherSource.Processor. A PublisherSource.Processor decouples production of data from the consumption of data and this holder acts as the implementation for that decoupling by using an intermediate in-memory storage. This in-memory storage layer can be used in different ways, some of which are enumerated below:

• Implement a custom signal rejection strategy when some signals can be dropped in favor of others.
• Store reduced set of signals when intermediary signals can either be discarded or coalesced.
• Reverse order of consumption of items when stored signals reach a threshold.

Multi-threaded access

Implementations may assume that the consumption of the holder (methods tryConsume(ProcessorSignalsConsumer) and tryConsumeTerminal(ProcessorSignalsConsumer)) is always done serially however the production (methods add(Object), terminate(Throwable) and terminate()) can be done concurrently.

Method Summary

Modifier and Type	Method and Description
void	add(T item) Adds an item to this holder.
void	terminate() Terminates this holder, such that no further modifications of this holder are allowed.
void	terminate(Throwable cause) Terminates this holder, such that no further modifications of this holder are allowed.
boolean	tryConsume(ProcessorSignalsConsumer<T> consumer) Try to consume the next item stored in this holder.
boolean	tryConsumeTerminal(ProcessorSignalsConsumer<T> consumer) If there are no items stored in the holder and the holder has terminated successfully or with an error then consume that successful or failed termination.

Method Detail

add

void add(@Nullable
         T item)

Adds an item to this holder.

Parameters:

item - to add.

terminate

void terminate()

Terminates this holder, such that no further modifications of this holder are allowed. Subsequent consumptions must first consume all previously added items and then ProcessorSignalsConsumer.consumeTerminal() consume termination}.

terminate

void terminate(Throwable cause)

Terminates this holder, such that no further modifications of this holder are allowed. Subsequent consumptions must first consume all previously added items and then ProcessorSignalsConsumer.consumeTerminal() consume termination}.

Parameters:

cause - Throwable as a cause for termination.

tryConsume

boolean tryConsume(ProcessorSignalsConsumer<T> consumer)

Try to consume the next item stored in this holder. If there are no items stored in the holder and the holder has terminated successfully or with an error then consume that successful or failed termination.

Parameters:

consumer - ProcessorSignalsConsumer to consume the next item or termination in this holder

Returns:

true if any method was called on the passed ProcessorSignalsConsumer.

tryConsumeTerminal

boolean tryConsumeTerminal(ProcessorSignalsConsumer<T> consumer)

If there are no items stored in the holder and the holder has terminated successfully or with an error then consume that successful or failed termination. If there are items in the holder then this method does nothing.

Parameters:

consumer - ProcessorSignalsConsumer to consume the next item or termination in this holder

Returns:

true if a terminal event was consumed by the passed ProcessorSignalsConsumer.