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.maybe;
  
  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;
  
  /**
   * Delay the subscription to the main Maybe until the other signals an item or completes.
   * 
   * @param <T> the main value type
   * @param <U> the other value type
   */
  public final class MaybeDelaySubscriptionOtherPublisher<T, U> extends AbstractMaybeWithUpstream<T, T> {
  
      final Publisher<U> other;
  
      public MaybeDelaySubscriptionOtherPublisher(MaybeSource<T> source, Publisher<U> other) {
          super(source);
          this.other = other;
      }
  
      @Override
      protected void subscribeActual(MaybeObserver<? super T> observer) {
          other.subscribe(new OtherSubscriber<>(observer, source));
      }
  
      static final class OtherSubscriber<T> implements FlowableSubscriber<Object>, Disposable {
          final DelayMaybeObserver<T> main;
  
          MaybeSource<T> source;
  
          Subscription upstream;
  
          OtherSubscriber(MaybeObserver<? super T> actual, MaybeSource<T> source) {
              this.main = new DelayMaybeObserver<>(actual);
              this.source = source;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
  
                  main.downstream.onSubscribe(this);
  
                  s.request(Long.MAX_VALUE);
              }
          }
  
          @Override
          public void onNext(Object t) {
              if (upstream != SubscriptionHelper.CANCELLED) {
                  upstream.cancel();
                  upstream = SubscriptionHelper.CANCELLED;
  
                  subscribeNext();
              }
          }
  
          @Override
          public void onError(Throwable t) {
              if (upstream != SubscriptionHelper.CANCELLED) {
                  upstream = SubscriptionHelper.CANCELLED;
  
                  main.downstream.onError(t);
              } else {
                  RxJavaPlugins.onError(t);
              }
          }
  
          @Override
          public void onComplete() {
              if (upstream != SubscriptionHelper.CANCELLED) {
                  upstream = SubscriptionHelper.CANCELLED;
  
                  subscribeNext();
              }
          }
  
          void subscribeNext() {
              MaybeSource<T> src = source;
              source = null;
  
              src.subscribe(main);
          }
  
          @Override
          public boolean isDisposed() {
              return DisposableHelper.isDisposed(main.get());
          }
  
          @Override
          public void dispose() {
              upstream.cancel();
              upstream = SubscriptionHelper.CANCELLED;
              DisposableHelper.dispose(main);
          }
      }
  
      static final class DelayMaybeObserver<T> extends AtomicReference<Disposable>
      implements MaybeObserver<T> {
  
          private static final long serialVersionUID = 706635022205076709L;
  
          final MaybeObserver<? super T> downstream;
  
          DelayMaybeObserver(MaybeObserver<? super T> downstream) {
              this.downstream = downstream;
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              DisposableHelper.setOnce(this, d);
          }
  
          @Override
          public void onSuccess(T value) {
              downstream.onSuccess(value);
          }
  
          @Override
          public void onError(Throwable e) {
              downstream.onError(e);
          }
  
          @Override
          public void onComplete() {
              downstream.onComplete();
          }
      }
  }
  