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.*;
  
  import org.reactivestreams.Subscriber;
  
  import io.reactivex.rxjava3.core.Flowable;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.internal.subscriptions.DeferredScalarSubscription;
  import io.reactivex.rxjava3.internal.util.ExceptionHelper;
  
  public final class FlowableFromFuture<T> extends Flowable<T> {
      final Future<? extends T> future;
      final long timeout;
      final TimeUnit unit;
  
      public FlowableFromFuture(Future<? extends T> future, long timeout, TimeUnit unit) {
          this.future = future;
          this.timeout = timeout;
          this.unit = unit;
      }
  
      @Override
      public void subscribeActual(Subscriber<? super T> s) {
          DeferredScalarSubscription<T> deferred = new DeferredScalarSubscription<>(s);
          s.onSubscribe(deferred);
  
          T v;
          try {
              v = unit != null ? future.get(timeout, unit) : future.get();
          } catch (Throwable ex) {
              Exceptions.throwIfFatal(ex);
              if (!deferred.isCancelled()) {
                  s.onError(ex);
              }
              return;
          }
          if (v == null) {
              s.onError(ExceptionHelper.createNullPointerException("The future returned a null value."));
          } else {
              deferred.complete(v);
          }
      }
  }
  