monix.reactive.internal.builders.FutureAsObservable.scala Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of monix-reactive_sjs1_2.13 Show documentation

Sub-module of Monix, exposing the Observable pattern for modeling of reactive streams. See: https://monix.io

The newest version!

/*
 * Copyright (c) 2014-2021 by The Monix Project Developers.
 * See the project homepage at: https://monix.io
 *
 * 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 monix.reactive.internal.builders

import scala.util.control.NonFatal
import monix.execution.{Cancelable, CancelableFuture}
import monix.reactive.Observable
import monix.reactive.observers.Subscriber

import scala.concurrent.Future
import scala.util.{Failure, Success}

/** Converts any `Future` into an observable */
private[reactive] final class FutureAsObservable[A](factory: => Future[A]) extends Observable[A] {

  def unsafeSubscribeFn(subscriber: Subscriber[A]): Cancelable = {
    import subscriber.{scheduler => s}
    // Protects calls to user code
    var streamErrors = true
    try {
      val evaluated = factory
      streamErrors = false

      evaluated.value match {
        case Some(Success(value)) =>
          subscriber.onNext(value)
          subscriber.onComplete()
          Cancelable.empty
        case Some(Failure(ex)) =>
          subscriber.onError(ex)
          Cancelable.empty
        case None =>
          evaluated.onComplete {
            case Success(value) =>
              subscriber.onNext(value)
              subscriber.onComplete()
            case Failure(ex) =>
              subscriber.onError(ex)
          }

          evaluated match {
            case c: CancelableFuture[_] => c
            case _ => Cancelable.empty
          }
      }
    } catch {
      case NonFatal(ex) if streamErrors =>
        subscriber.onError(ex)
        Cancelable.empty
    }
  }
}