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UniOperatorProcessor.java
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UniOperatorProcessor.java
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package io.smallrye.mutiny.operators.uni;
import static io.smallrye.mutiny.helpers.EmptyUniSubscription.CANCELLED;
import static io.smallrye.mutiny.helpers.EmptyUniSubscription.DONE;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import io.smallrye.mutiny.helpers.ParameterValidation;
import io.smallrye.mutiny.infrastructure.Infrastructure;
import io.smallrye.mutiny.subscription.UniSubscriber;
import io.smallrye.mutiny.subscription.UniSubscription;
public abstract class UniOperatorProcessor<I, O> implements UniSubscriber<I>, UniSubscription {
protected final UniSubscriber<? super O> downstream;
private static final AtomicReferenceFieldUpdater<UniOperatorProcessor, UniSubscription> updater = AtomicReferenceFieldUpdater
.newUpdater(UniOperatorProcessor.class, UniSubscription.class, "upstream");
private volatile UniSubscription upstream;
public UniOperatorProcessor(UniSubscriber<? super O> downstream) {
this.downstream = ParameterValidation.nonNull(downstream, "downstream");
}
@Override
public void onSubscribe(UniSubscription subscription) {
if (compareAndSetUpstreamSubscription(null, subscription)) {
downstream.onSubscribe(this);
} else {
subscription.cancel();
}
}
@Override
@SuppressWarnings("unchecked")
public void onItem(I item) {
UniSubscription subscription = getAndSetUpstreamSubscription(CANCELLED);
if (subscription != CANCELLED) {
downstream.onItem((O) item);
}
}
@Override
public void onFailure(Throwable failure) {
UniSubscription subscription = getAndSetUpstreamSubscription(CANCELLED);
if (subscription != CANCELLED) {
downstream.onFailure(failure);
} else {
Infrastructure.handleDroppedException(failure);
}
}
@Override
public void cancel() {
UniSubscription subscription = getAndSetUpstreamSubscription(CANCELLED);
if (subscription != null && subscription != CANCELLED && subscription != DONE) {
subscription.cancel();
}
}
public boolean isCancelled() {
return upstream == CANCELLED;
}
protected final UniSubscription getCurrentUpstreamSubscription() {
return upstream;
}
protected final UniSubscription getAndSetUpstreamSubscription(UniSubscription newValue) {
return updater.getAndSet(this, newValue);
}
protected final boolean compareAndSetUpstreamSubscription(UniSubscription expect, UniSubscription update) {
return updater.compareAndSet(this, expect, update);
}
}