Package com.linecorp.armeria.common.stream

Class FilteredStreamMessage<T,U>

java.lang.Object

com.linecorp.armeria.common.stream.FilteredStreamMessage<T,U>

All Implemented Interfaces:

StreamMessage<U>, org.reactivestreams.Publisher<U>

Direct Known Subclasses:

FilteredHttpRequest, FilteredHttpResponse

public abstract class FilteredStreamMessage<T,U>
extends Object
implements StreamMessage<U>

A StreamMessage that filters objects as they are published. The filtering will happen from an I/O thread, meaning the order of the filtering will match the order that the delegate processes the objects in.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	FilteredStreamMessage(StreamMessage<T> delegate)	Creates a new FilteredStreamMessage that filters objects published by delegate before passing to a subscriber.
protected	FilteredStreamMessage(StreamMessage<T> delegate, boolean withPooledObjects)	Creates a new FilteredStreamMessage that filters objects published by delegate before passing to a subscriber.

Method Summary

Modifier and Type	Method	Description
void	abort()	Closes this stream with AbortedStreamException and prevents further subscription.
void	abort(Throwable cause)	Closes this stream with the specified Throwable and prevents further subscription.
protected void	beforeComplete(org.reactivestreams.Subscriber<? super U> subscriber)	A callback executed just before calling Subscriber.onComplete() on subscriber.
protected Throwable	beforeError(org.reactivestreams.Subscriber<? super U> subscriber, Throwable cause)	A callback executed just before calling Subscriber.onError(Throwable) on subscriber.
protected void	beforeSubscribe(org.reactivestreams.Subscriber<? super U> subscriber, org.reactivestreams.Subscription subscription)	A callback executed just before calling Subscriber.onSubscribe(Subscription) on subscriber.
EventExecutor	defaultSubscriberExecutor()	Returns the default EventExecutor which will be used when a user subscribes using StreamMessage.subscribe(Subscriber), StreamMessage.subscribe(Subscriber, SubscriptionOption...), StreamMessage.drainAll() and StreamMessage.drainAll(SubscriptionOption...).
CompletableFuture<List<U>>	drainAll(EventExecutor executor)	Subscribes to this StreamMessage and retrieves all elements from it.
CompletableFuture<List<U>>	drainAll(EventExecutor executor, SubscriptionOption... options)	Subscribes to this StreamMessage and retrieves all elements from it.
protected abstract U	filter(T obj)	The filter to apply to published objects.
boolean	isEmpty()	Returns true if this stream has been closed and did not publish any elements.
boolean	isOpen()	Returns true if this stream is not closed yet.
void	subscribe(org.reactivestreams.Subscriber<? super U> subscriber, EventExecutor executor)	Requests to start streaming data to the specified Subscriber.
void	subscribe(org.reactivestreams.Subscriber<? super U> subscriber, EventExecutor executor, SubscriptionOption... options)	Requests to start streaming data to the specified Subscriber.
CompletableFuture<Void>	whenComplete()	Returns a CompletableFuture that completes when this stream is complete, either successfully or exceptionally, including cancellation and abortion.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.linecorp.armeria.common.stream.StreamMessage

drainAll, drainAll, isComplete, subscribe, subscribe, toDuplicator, toDuplicator

Constructor Details

FilteredStreamMessage

protected FilteredStreamMessage(StreamMessage<T> delegate)

Creates a new FilteredStreamMessage that filters objects published by delegate before passing to a subscriber.

FilteredStreamMessage

protected FilteredStreamMessage(StreamMessage<T> delegate, boolean withPooledObjects)

Creates a new FilteredStreamMessage that filters objects published by delegate before passing to a subscriber.

Parameters:

withPooledObjects - if true, filter(Object) receives the pooled ByteBuf and ByteBufHolder as is, without making a copy. If you don't know what this means, use FilteredStreamMessage(StreamMessage).

Method Details

filter

protected abstract U filter(T obj)

The filter to apply to published objects. The result of the filter is passed on to the delegate subscriber.

beforeSubscribe

protected void beforeSubscribe(org.reactivestreams.Subscriber<? super U> subscriber, org.reactivestreams.Subscription subscription)

A callback executed just before calling Subscriber.onSubscribe(Subscription) on subscriber. Override this method to execute any initialization logic that may be needed.

beforeComplete

protected void beforeComplete(org.reactivestreams.Subscriber<? super U> subscriber)

A callback executed just before calling Subscriber.onComplete() on subscriber. Override this method to execute any cleanup logic that may be needed before completing the subscription.

beforeError

@Nullable protected Throwable beforeError(org.reactivestreams.Subscriber<? super U> subscriber, Throwable cause)

A callback executed just before calling Subscriber.onError(Throwable) on subscriber. Override this method to execute any cleanup logic that may be needed before failing the subscription. This method may rewrite the cause and then return a new one so that the new Throwable would be passed to Subscriber.onError(Throwable).

isOpen

public boolean isOpen()

Description copied from interface: StreamMessage

Returns true if this stream is not closed yet. Note that a stream may not be complete even if it's closed; a stream is complete when it's fully consumed by a Subscriber.

Specified by:

isOpen in interface StreamMessage<T>

isEmpty

public boolean isEmpty()

Description copied from interface: StreamMessage

Returns true if this stream has been closed and did not publish any elements. Note that this method will not return true when the stream is open even if it has not published anything so far, because it may publish something later.

Specified by:

isEmpty in interface StreamMessage<T>

whenComplete

public CompletableFuture<Void> whenComplete()

Description copied from interface: StreamMessage

Returns a CompletableFuture that completes when this stream is complete, either successfully or exceptionally, including cancellation and abortion.

A StreamMessage is complete (or 'fully consumed') when:

• the Subscriber consumes all elements and Subscriber.onComplete() is invoked,
• an error occurred and Subscriber.onError(Throwable) is invoked,
• the Subscription has been cancelled or
• StreamMessage.abort() has been requested.

Specified by:

whenComplete in interface StreamMessage<T>

subscribe

public void subscribe(org.reactivestreams.Subscriber<? super U> subscriber, EventExecutor executor)

Description copied from interface: StreamMessage

Requests to start streaming data to the specified Subscriber. If there is a problem subscribing, Subscriber.onError(Throwable) will be invoked with one of the following exceptions:

• IllegalStateException if other Subscriber subscribed to this stream already.
• AbortedStreamException if this stream has been aborted.
• CancelledSubscriptionException if this stream has been cancelled and SubscriptionOption.NOTIFY_CANCELLATION is specified when subscribed.
• Other exceptions that occurred due to an error while retrieving the elements.

Specified by:

subscribe in interface StreamMessage<T>

executor - the executor to subscribe

subscribe

public void subscribe(org.reactivestreams.Subscriber<? super U> subscriber, EventExecutor executor, SubscriptionOption... options)

Description copied from interface: StreamMessage

Requests to start streaming data to the specified Subscriber. If there is a problem subscribing, Subscriber.onError(Throwable) will be invoked with one of the following exceptions:

• IllegalStateException if other Subscriber subscribed to this stream already.
• AbortedStreamException if this stream has been aborted.
• CancelledSubscriptionException if this stream has been cancelled and SubscriptionOption.NOTIFY_CANCELLATION is specified when subscribed.
• Other exceptions that occurred due to an error while retrieving the elements.

Specified by:

subscribe in interface StreamMessage<T>

executor - the executor to subscribe

options - SubscriptionOptions to subscribe with

drainAll

public CompletableFuture<List<U>> drainAll(EventExecutor executor)

Description copied from interface: StreamMessage

Subscribes to this StreamMessage and retrieves all elements from it. The returned CompletableFuture may be completed exceptionally with the following exceptions:

• IllegalStateException if other Subscriber subscribed to this stream already.
• AbortedStreamException if this stream has been aborted.
• Other exceptions that occurred due to an error while retrieving the elements.

Specified by:

drainAll in interface StreamMessage<T>

Parameters:

executor - the executor to retrieve all elements

Returns:

the CompletableFuture which will be completed with the list of the elements retrieved.

drainAll

public CompletableFuture<List<U>> drainAll(EventExecutor executor, SubscriptionOption... options)

Description copied from interface: StreamMessage

Subscribes to this StreamMessage and retrieves all elements from it. The returned CompletableFuture may be completed exceptionally with the following exceptions:

• IllegalStateException if other Subscriber subscribed to this stream already.
• AbortedStreamException if this stream has been aborted.
• Other exceptions that occurred due to an error while retrieving the elements.

Specified by:

drainAll in interface StreamMessage<T>

Parameters:

executor - the executor to retrieve all elements

options - SubscriptionOptions to subscribe with. Note that SubscriptionOption.NOTIFY_CANCELLATION is ineffective because there's no cancelling while draining all elements.

Returns:

the CompletableFuture which will be completed with the list of the elements retrieved.

defaultSubscriberExecutor

public EventExecutor defaultSubscriberExecutor()

Description copied from interface: StreamMessage

Returns the default EventExecutor which will be used when a user subscribes using StreamMessage.subscribe(Subscriber), StreamMessage.subscribe(Subscriber, SubscriptionOption...), StreamMessage.drainAll() and StreamMessage.drainAll(SubscriptionOption...).

Please note that if this method is called multiple times, the returned EventExecutors can be different depending on this StreamMessage implementation.

Specified by:

defaultSubscriberExecutor in interface StreamMessage<T>

abort

public void abort()

Description copied from interface: StreamMessage

Closes this stream with AbortedStreamException and prevents further subscription. A Subscriber that attempts to subscribe to an aborted stream will be notified with an AbortedStreamException via Subscriber.onError(Throwable). Calling this method on a closed or aborted stream has no effect.

Specified by:

abort in interface StreamMessage<T>

abort

public void abort(Throwable cause)

Description copied from interface: StreamMessage

Closes this stream with the specified Throwable and prevents further subscription. A Subscriber that attempts to subscribe to an aborted stream will be notified with the specified Throwable via Subscriber.onError(Throwable). Calling this method on a closed or aborted stream has no effect.

Specified by:

abort in interface StreamMessage<T>