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Consume.java
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Consume.java
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/*
* Copyright (c) 2019 Contributors to the Eclipse Foundation
*
* See the NOTICE file(s) distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0
*
* SPDX-License-Identifier: EPL-2.0
*/
package org.eclipse.ditto.internal.utils.pekko.controlflow;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import org.eclipse.ditto.base.model.headers.WithDittoHeaders;
import org.apache.pekko.NotUsed;
import org.apache.pekko.actor.ActorRef;
import org.apache.pekko.stream.Graph;
import org.apache.pekko.stream.SinkShape;
import org.apache.pekko.stream.javadsl.Sink;
/**
* An Akka stream sink from a consumer of messages with sender.
*/
public final class Consume {
private Consume() {
throw new AssertionError();
}
/**
* Create sink from consumer of {@code WithSender}.
*
* @param consumer the consumer.
* @param <T> type of messages.
* @param <S> some supertype of messages.
* @return sink.
*/
@SuppressWarnings("unchecked")
public static <S extends WithDittoHeaders, T extends S> Graph<SinkShape<WithSender<T>>, NotUsed> of(final Consumer<WithSender<S>> consumer) {
// need to cast WithSender<T> to WithSender<S> because java does not understand covariance
return Sink.<WithSender<T>>foreach(w -> consumer.accept((WithSender<S>) w))
.mapMaterializedValue(x -> NotUsed.getInstance());
}
/**
* Create sink from bi-consumer of message and sender.
*
* @param biConsumer the bi-consumer.
* @param <T> type of messages.
* @return sink.
*/
public static <T extends WithDittoHeaders> Graph<SinkShape<WithSender<T>>, NotUsed> of(final BiConsumer<? super T, ActorRef> biConsumer) {
return of(withSender -> biConsumer.accept(withSender.getMessage(), withSender.getSender()));
}
/**
* Create sink from consumer accepting all message types.
*
* @param consumer the consumer.
* @return sink.
*/
@SuppressWarnings("unchecked")
public static Graph<SinkShape<WithSender<?>>, NotUsed> untyped(final Consumer<WithSender<?>> consumer) {
// Ignore complaints from Java type checker. The consumer can clearly handle all inputs.
return (Graph<SinkShape<WithSender<?>>, NotUsed>) (Object) of(consumer::accept);
}
}