code: /*
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.rxjava3.internal.operators.single;
  
  import java.util.concurrent.CancellationException;
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
  import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  /**
   * Signals the events of the source Single or signals a CancellationException if the
   * other Publisher signalled first.
   * @param <T> the main value type
   * @param <U> the other value type
   */
  public final class SingleTakeUntil<T, U> extends Single<T> {
  
      final SingleSource<T> source;
  
      final Publisher<U> other;
  
      public SingleTakeUntil(SingleSource<T> source, Publisher<U> other) {
          this.source = source;
          this.other = other;
      }
  
      @Override
      protected void subscribeActual(SingleObserver<? super T> observer) {
          TakeUntilMainObserver<T> parent = new TakeUntilMainObserver<>(observer);
          observer.onSubscribe(parent);
  
          other.subscribe(parent.other);
  
          source.subscribe(parent);
      }
  
      static final class TakeUntilMainObserver<T>
      extends AtomicReference<Disposable>
      implements SingleObserver<T>, Disposable {
  
          private static final long serialVersionUID = -622603812305745221L;
  
          final SingleObserver<? super T> downstream;
  
          final TakeUntilOtherSubscriber other;
  
          TakeUntilMainObserver(SingleObserver<? super T> downstream) {
              this.downstream = downstream;
              this.other = new TakeUntilOtherSubscriber(this);
          }
  
          @Override
          public void dispose() {
              DisposableHelper.dispose(this);
              other.dispose();
          }
  
          @Override
          public boolean isDisposed() {
              return DisposableHelper.isDisposed(get());
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              DisposableHelper.setOnce(this, d);
          }
  
          @Override
          public void onSuccess(T value) {
              other.dispose();
  
              Disposable a = getAndSet(DisposableHelper.DISPOSED);
              if (a != DisposableHelper.DISPOSED) {
                  downstream.onSuccess(value);
              }
          }
  
          @Override
          public void onError(Throwable e) {
              other.dispose();
  
              Disposable a = get();
              if (a != DisposableHelper.DISPOSED) {
                  a = getAndSet(DisposableHelper.DISPOSED);
                  if (a != DisposableHelper.DISPOSED) {
                      downstream.onError(e);
                      return;
                  }
              }
              RxJavaPlugins.onError(e);
          }
  
          void otherError(Throwable e) {
              Disposable a = get();
              if (a != DisposableHelper.DISPOSED) {
                  a = getAndSet(DisposableHelper.DISPOSED);
                  if (a != DisposableHelper.DISPOSED) {
                      if (a != null) {
                          a.dispose();
                      }
                      downstream.onError(e);
                      return;
                  }
              }
              RxJavaPlugins.onError(e);
          }
      }
  
      static final class TakeUntilOtherSubscriber
      extends AtomicReference<Subscription>
      implements FlowableSubscriber<Object> {
  
          private static final long serialVersionUID = 5170026210238877381L;
  
          final TakeUntilMainObserver<?> parent;
  
          TakeUntilOtherSubscriber(TakeUntilMainObserver<?> parent) {
              this.parent = parent;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              SubscriptionHelper.setOnce(this, s, Long.MAX_VALUE);
          }
  
          @Override
          public void onNext(Object t) {
              if (SubscriptionHelper.cancel(this)) {
                  parent.otherError(new CancellationException());
              }
          }
  
          @Override
          public void onError(Throwable t) {
              parent.otherError(t);
          }
  
          @Override
          public void onComplete() {
              if (get() != SubscriptionHelper.CANCELLED) {
                  lazySet(SubscriptionHelper.CANCELLED);
                  parent.otherError(new CancellationException());
              }
          }
  
          public void dispose() {
              SubscriptionHelper.cancel(this);
          }
      }
  }
  