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 io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.internal.disposables.*;
  /**
   * Subscribes to the upstream MaybeSource on the specified scheduler.
   *
   * @param <T> the value type delivered
   */
  public final class MaybeSubscribeOn<T> extends AbstractMaybeWithUpstream<T, T> {
  
      final Scheduler scheduler;
  
      public MaybeSubscribeOn(MaybeSource<T> source, Scheduler scheduler) {
          super(source);
          this.scheduler = scheduler;
      }
  
      @Override
      protected void subscribeActual(MaybeObserver<? super T> observer) {
          SubscribeOnMaybeObserver<T> parent = new SubscribeOnMaybeObserver<>(observer);
          observer.onSubscribe(parent);
  
          parent.task.replace(scheduler.scheduleDirect(new SubscribeTask<>(parent, source)));
      }
  
      static final class SubscribeTask<T> implements Runnable {
          final MaybeObserver<? super T> observer;
          final MaybeSource<T> source;
  
          SubscribeTask(MaybeObserver<? super T> observer, MaybeSource<T> source) {
              this.observer = observer;
              this.source = source;
          }
  
          @Override
          public void run() {
              source.subscribe(observer);
          }
      }
  
      static final class SubscribeOnMaybeObserver<T>
      extends AtomicReference<Disposable>
      implements MaybeObserver<T>, Disposable {
  
          final SequentialDisposable task;
  
          private static final long serialVersionUID = 8571289934935992137L;
  
          final MaybeObserver<? super T> downstream;
  
          SubscribeOnMaybeObserver(MaybeObserver<? super T> downstream) {
              this.downstream = downstream;
              this.task = new SequentialDisposable();
          }
  
          @Override
          public void dispose() {
              DisposableHelper.dispose(this);
              task.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) {
              downstream.onSuccess(value);
          }
  
          @Override
          public void onError(Throwable e) {
              downstream.onError(e);
          }
  
          @Override
          public void onComplete() {
              downstream.onComplete();
          }
      }
  }
  