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.observers;
  
  import java.util.Queue;
  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;
  import io.reactivex.rxjava3.internal.util.NotificationLite;
  
  public final class BlockingObserver<T> extends AtomicReference<Disposable> implements Observer<T>, Disposable {
  
      private static final long serialVersionUID = -4875965440900746268L;
  
      public static final Object TERMINATED = new Object();
  
      final Queue<Object> queue;
  
      public BlockingObserver(Queue<Object> queue) {
          this.queue = queue;
      }
  
      @Override
      public void onSubscribe(Disposable d) {
          DisposableHelper.setOnce(this, d);
      }
  
      @Override
      public void onNext(T t) {
          queue.offer(NotificationLite.next(t));
      }
  
      @Override
      public void onError(Throwable t) {
          queue.offer(NotificationLite.error(t));
      }
  
      @Override
      public void onComplete() {
          queue.offer(NotificationLite.complete());
      }
  
      @Override
      public void dispose() {
          if (DisposableHelper.dispose(this)) {
              queue.offer(TERMINATED);
          }
      }
  
      @Override
      public boolean isDisposed() {
          return get() == DisposableHelper.DISPOSED;
      }
  }
  