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.TimeUnit;
  import java.util.concurrent.atomic.AtomicReference;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.core.Scheduler.Worker;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Consumer;
  import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
  import io.reactivex.rxjava3.observers.SerializedObserver;
  
  public final class ObservableThrottleFirstTimed<T> extends AbstractObservableWithUpstream<T, T> {
      final long timeout;
      final TimeUnit unit;
      final Scheduler scheduler;
      final Consumer<? super T> onDropped;
  
      public ObservableThrottleFirstTimed(
              ObservableSource<T> source,
              long timeout,
              TimeUnit unit,
              Scheduler scheduler,
              Consumer<? super T> onDropped) {
          super(source);
          this.timeout = timeout;
          this.unit = unit;
          this.scheduler = scheduler;
          this.onDropped = onDropped;
      }
  
      @Override
      public void subscribeActual(Observer<? super T> t) {
          source.subscribe(new DebounceTimedObserver<>(
                  new SerializedObserver<>(t),
                  timeout, unit, scheduler.createWorker(),
                  onDropped));
      }
  
      static final class DebounceTimedObserver<T>
      extends AtomicReference<Disposable>
      implements Observer<T>, Disposable, Runnable {
          private static final long serialVersionUID = 786994795061867455L;
  
          final Observer<? super T> downstream;
          final long timeout;
          final TimeUnit unit;
          final Scheduler.Worker worker;
          final Consumer<? super T> onDropped;
          Disposable upstream;
          volatile boolean gate;
  
          DebounceTimedObserver(
                  Observer<? super T> actual,
                  long timeout,
                  TimeUnit unit,
                  Worker worker,
                  Consumer<? super T> onDropped) {
              this.downstream = actual;
              this.timeout = timeout;
              this.unit = unit;
              this.worker = worker;
              this.onDropped = onDropped;
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              if (DisposableHelper.validate(this.upstream, d)) {
                  this.upstream = d;
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              if (!gate) {
                  gate = true;
  
                  downstream.onNext(t);
  
                  Disposable d = get();
                  if (d != null) {
                      d.dispose();
                  }
                  DisposableHelper.replace(this, worker.schedule(this, timeout, unit));
              } else if (onDropped != null) {
                  try {
                      onDropped.accept(t);
                  } catch (Throwable ex) {
                      Exceptions.throwIfFatal(ex);
                      upstream.dispose();
                      downstream.onError(ex);
                      worker.dispose();
                  }
              }
          }
  
          @Override
          public void run() {
              gate = false;
          }
  
          @Override
          public void onError(Throwable t) {
              downstream.onError(t);
              worker.dispose();
          }
  
          @Override
          public void onComplete() {
              downstream.onComplete();
              worker.dispose();
          }
  
          @Override
          public void dispose() {
              upstream.dispose();
              worker.dispose();
          }
  
          @Override
          public boolean isDisposed() {
              return worker.isDisposed();
          }
      }
  }
  