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MultiCollectorOp.java
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MultiCollectorOp.java
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package io.smallrye.mutiny.operators.multi;
import static io.smallrye.mutiny.helpers.EmptyUniSubscription.CANCELLED;
import static io.smallrye.mutiny.helpers.ParameterValidation.SUPPLIER_PRODUCED_NULL;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.stream.Collector;
import org.reactivestreams.Subscription;
import io.smallrye.mutiny.Multi;
import io.smallrye.mutiny.helpers.Subscriptions;
import io.smallrye.mutiny.subscription.MultiSubscriber;
public final class MultiCollectorOp<T, A, R> extends AbstractMultiOperator<T, R> {
private final Collector<? super T, A, ? extends R> collector;
private final boolean acceptNullAsInitialValue;
public MultiCollectorOp(Multi<T> upstream, Collector<? super T, A, ? extends R> collector,
boolean acceptNullAsInitialValue) {
super(upstream);
this.collector = collector;
this.acceptNullAsInitialValue = acceptNullAsInitialValue;
}
@Override
public void subscribe(MultiSubscriber<? super R> downstream) {
A initialValue;
BiConsumer<A, ? super T> accumulator;
Function<A, ? extends R> finisher;
try {
initialValue = collector.supplier().get();
accumulator = collector.accumulator();
finisher = collector.finisher();
} catch (Throwable ex) {
Subscriptions.fail(downstream, ex, upstream);
return;
}
if (initialValue == null && !acceptNullAsInitialValue) {
Subscriptions.fail(downstream, new NullPointerException(SUPPLIER_PRODUCED_NULL), upstream);
return;
}
if (accumulator == null) {
Subscriptions.fail(downstream, new NullPointerException("`accumulator` must not be `null`"), upstream);
return;
}
CollectorProcessor<? super T, A, ? extends R> processor = new CollectorProcessor<>(downstream, initialValue,
accumulator, finisher);
upstream.subscribe().withSubscriber(processor);
}
static class CollectorProcessor<T, A, R> extends MultiOperatorProcessor<T, R> {
private final BiConsumer<A, T> accumulator;
private final Function<A, R> finisher;
// Only accessed in the serialized callbacks
private A intermediate;
CollectorProcessor(MultiSubscriber<? super R> downstream,
A initialValue, BiConsumer<A, T> accumulator, Function<A, R> finisher) {
super(downstream);
this.intermediate = initialValue;
this.accumulator = accumulator;
this.finisher = finisher;
}
@Override
public void onItem(T item) {
if (getUpstreamSubscription() != CANCELLED) {
try {
accumulator.accept(intermediate, item);
} catch (Throwable ex) {
failAndCancel(ex);
}
}
}
@Override
public void onCompletion() {
Subscription subscription = getAndSetUpstreamSubscription(Subscriptions.CANCELLED);
if (subscription != Subscriptions.CANCELLED) {
R result;
MultiSubscriber<? super R> subscriber = downstream;
try {
result = finisher.apply(intermediate);
} catch (Throwable ex) {
subscriber.onFailure(ex);
return;
}
intermediate = null;
if (result != null) {
subscriber.onItem(result);
}
subscriber.onCompletion();
}
}
@Override
public void request(long n) {
// The subscriber may request only 1 but as we don't know how much we get, we request MAX.
// This could be changed with call to request in the OnNext/OnItem
super.request(Long.MAX_VALUE);
}
}
}