monix.reactive.internal.operators.DoOnTerminateOperator.scala Maven / Gradle / Ivy
/*
* Copyright (c) 2014-2020 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.operators
import monix.execution.Callback
import monix.eval.Task
import monix.execution.Ack
import monix.execution.Ack.{Continue, Stop}
import monix.execution.atomic.Atomic
import scala.util.control.NonFatal
import monix.reactive.internal.util.Instances._
import monix.reactive.Observable.Operator
import monix.reactive.observers.Subscriber
import scala.concurrent.Future
import scala.util.Success
private[reactive] final class DoOnTerminateOperator[A](
onTerminate: Option[Throwable] => Task[Unit],
happensBefore: Boolean)
extends Operator[A, A] {
def apply(out: Subscriber[A]): Subscriber[A] =
new Subscriber[A] {
// Wrapping in a cancelable in order to protect it from
// being called multiple times
private[this] val active = Atomic(true)
implicit val scheduler = out.scheduler
def onNext(elem: A): Future[Ack] = {
val result =
try out.onNext(elem)
catch { case ex if NonFatal(ex) => Future.failed(ex) }
val task = Task.fromFuture(result).attempt.flatMap {
case Right(ack) =>
ack match {
case Continue => ContinueTask
case Stop =>
onTerminate(None).map(_ => Stop)
}
case Left(ex) =>
onError(ex)
onTerminate(Some(ex)).map(_ => Stop)
}
val errorCoverage = task.onErrorHandle { ex =>
scheduler.reportFailure(ex)
Stop
}
val future = errorCoverage.runToFuture
// Execution might be immediate
future.value match {
case Some(Success(ack)) => ack
case _ => future
}
}
private def onFinish(ex: Option[Throwable]): Task[Unit] = {
@inline def triggerSignal(): Unit = ex match {
case None => out.onComplete()
case Some(ref) => out.onError(ref)
}
if (active.getAndSet(false)) {
var streamErrors = true
try if (happensBefore) {
val task = onTerminate(ex).onErrorHandle { ex =>
scheduler.reportFailure(ex)
}
streamErrors = false
task.map { _ =>
triggerSignal()
}
} else {
streamErrors = false
triggerSignal()
onTerminate(ex)
} catch {
case err if NonFatal(err) =>
if (streamErrors) {
out.onError(err)
ex.foreach(scheduler.reportFailure)
} else {
scheduler.reportFailure(err)
}
Task.unit
}
} else {
ex.foreach(scheduler.reportFailure)
Task.unit
}
}
def onComplete(): Unit =
onFinish(None).runAsync(Callback.empty)
def onError(ex: Throwable): Unit =
onFinish(Some(ex)).runAsync(Callback.empty)
}
}