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.observable;
  
  import java.util.concurrent.atomic.AtomicReference;
  
  import io.reactivex.rxjava3.core.Observer;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
  
  public final class ObserverResourceWrapper<T> extends AtomicReference<Disposable> implements Observer<T>, Disposable {
  
      private static final long serialVersionUID = -8612022020200669122L;
  
      final Observer<? super T> downstream;
  
      final AtomicReference<Disposable> upstream = new AtomicReference<>();
  
      public ObserverResourceWrapper(Observer<? super T> downstream) {
          this.downstream = downstream;
      }
  
      @Override
      public void onSubscribe(Disposable d) {
          if (DisposableHelper.setOnce(upstream, d)) {
              downstream.onSubscribe(this);
          }
      }
  
      @Override
      public void onNext(T t) {
          downstream.onNext(t);
      }
  
      @Override
      public void onError(Throwable t) {
          dispose();
          downstream.onError(t);
      }
  
      @Override
      public void onComplete() {
          dispose();
          downstream.onComplete();
      }
  
      @Override
      public void dispose() {
          DisposableHelper.dispose(upstream);
  
          DisposableHelper.dispose(this);
      }
  
      @Override
      public boolean isDisposed() {
          return upstream.get() == DisposableHelper.DISPOSED;
      }
  
      public void setResource(Disposable resource) {
          DisposableHelper.set(this, resource);
      }
  }
  