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.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
  import io.reactivex.rxjava3.observers.SerializedObserver;
  
  public final class ObservableSampleWithObservable<T> extends AbstractObservableWithUpstream<T, T> {
  
      final ObservableSource<?> other;
  
      final boolean emitLast;
  
      public ObservableSampleWithObservable(ObservableSource<T> source, ObservableSource<?> other, boolean emitLast) {
          super(source);
          this.other = other;
          this.emitLast = emitLast;
      }
  
      @Override
      public void subscribeActual(Observer<? super T> t) {
          SerializedObserver<T> serial = new SerializedObserver<>(t);
          if (emitLast) {
              source.subscribe(new SampleMainEmitLast<>(serial, other));
          } else {
              source.subscribe(new SampleMainNoLast<>(serial, other));
          }
      }
  
      abstract static class SampleMainObserver<T> extends AtomicReference<T>
      implements Observer<T>, Disposable {
  
          private static final long serialVersionUID = -3517602651313910099L;
  
          final Observer<? super T> downstream;
          final ObservableSource<?> sampler;
  
          final AtomicReference<Disposable> other = new AtomicReference<>();
  
          Disposable upstream;
  
          SampleMainObserver(Observer<? super T> actual, ObservableSource<?> other) {
              this.downstream = actual;
              this.sampler = other;
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              if (DisposableHelper.validate(this.upstream, d)) {
                  this.upstream = d;
                  downstream.onSubscribe(this);
                  if (other.get() == null) {
                      sampler.subscribe(new SamplerObserver<>(this));
                  }
              }
          }
  
          @Override
          public void onNext(T t) {
              lazySet(t);
          }
  
          @Override
          public void onError(Throwable t) {
              DisposableHelper.dispose(other);
              downstream.onError(t);
          }
  
          @Override
          public void onComplete() {
              DisposableHelper.dispose(other);
              completion();
          }
  
          boolean setOther(Disposable o) {
              return DisposableHelper.setOnce(other, o);
          }
  
          @Override
          public void dispose() {
              DisposableHelper.dispose(other);
              upstream.dispose();
          }
  
          @Override
          public boolean isDisposed() {
              return other.get() == DisposableHelper.DISPOSED;
          }
  
          public void error(Throwable e) {
              upstream.dispose();
              downstream.onError(e);
          }
  
          public void complete() {
              upstream.dispose();
              completion();
          }
  
          void emit() {
              T value = getAndSet(null);
              if (value != null) {
                  downstream.onNext(value);
              }
          }
  
          abstract void completion();
  
          abstract void run();
      }
  
      static final class SamplerObserver<T> implements Observer<Object> {
          final SampleMainObserver<T> parent;
          SamplerObserver(SampleMainObserver<T> parent) {
              this.parent = parent;
  
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              parent.setOther(d);
          }
  
          @Override
          public void onNext(Object t) {
              parent.run();
          }
  
          @Override
          public void onError(Throwable t) {
              parent.error(t);
          }
  
          @Override
          public void onComplete() {
              parent.complete();
          }
      }
  
      static final class SampleMainNoLast<T> extends SampleMainObserver<T> {
  
          private static final long serialVersionUID = -3029755663834015785L;
  
          SampleMainNoLast(Observer<? super T> actual, ObservableSource<?> other) {
              super(actual, other);
          }
  
          @Override
          void completion() {
              downstream.onComplete();
          }
  
          @Override
          void run() {
              emit();
          }
      }
  
      static final class SampleMainEmitLast<T> extends SampleMainObserver<T> {
  
          private static final long serialVersionUID = -3029755663834015785L;
  
          final AtomicInteger wip;
  
          volatile boolean done;
  
          SampleMainEmitLast(Observer<? super T> actual, ObservableSource<?> other) {
              super(actual, other);
              this.wip = new AtomicInteger();
          }
  
          @Override
          void completion() {
              done = true;
              if (wip.getAndIncrement() == 0) {
                  emit();
                  downstream.onComplete();
              }
          }
  
          @Override
          void run() {
              if (wip.getAndIncrement() == 0) {
                  do {
                      boolean d = done;
                      emit();
                      if (d) {
                          downstream.onComplete();
                          return;
                      }
                  } while (wip.decrementAndGet() != 0);
              }
          }
      }
  }
  