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.flowable;
  
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  public final class FlowableUnsubscribeOn<T> extends AbstractFlowableWithUpstream<T, T> {
      final Scheduler scheduler;
      public FlowableUnsubscribeOn(Flowable<T> source, Scheduler scheduler) {
          super(source);
          this.scheduler = scheduler;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          source.subscribe(new UnsubscribeSubscriber<>(s, scheduler));
      }
  
      static final class UnsubscribeSubscriber<T> extends AtomicBoolean implements FlowableSubscriber<T>, Subscription {
  
          private static final long serialVersionUID = 1015244841293359600L;
  
          final Subscriber<? super T> downstream;
          final Scheduler scheduler;
  
          Subscription upstream;
  
          UnsubscribeSubscriber(Subscriber<? super T> actual, Scheduler scheduler) {
              this.downstream = actual;
              this.scheduler = scheduler;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              if (!get()) {
                  downstream.onNext(t);
              }
          }
  
          @Override
          public void onError(Throwable t) {
              if (get()) {
                  RxJavaPlugins.onError(t);
                  return;
              }
              downstream.onError(t);
          }
  
          @Override
          public void onComplete() {
              if (!get()) {
                  downstream.onComplete();
              }
          }
  
          @Override
          public void request(long n) {
              upstream.request(n);
          }
  
          @Override
          public void cancel() {
              if (compareAndSet(false, true)) {
                  scheduler.scheduleDirect(new Cancellation());
              }
          }
  
          final class Cancellation implements Runnable {
              @Override
              public void run() {
                  upstream.cancel();
              }
          }
      }
  }
  