monix.reactive.internal.operators.RepeatSourceObservable.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.Ack.Continue
import monix.execution.cancelables.{CompositeCancelable, OrderedCancelable}
import monix.execution.{Ack, Cancelable}
import monix.reactive.Observable
import monix.reactive.observers.Subscriber
import monix.reactive.subjects.{ReplaySubject, Subject}
import scala.concurrent.Future
import scala.util.Success
private[reactive] final class RepeatSourceObservable[A](source: Observable[A]) extends Observable[A] {
// recursive function - subscribes the observer again when
// onComplete happens
def loop(subject: Subject[A, A], out: Subscriber[A], task: OrderedCancelable, index: Long): Unit = {
val cancelable = subject.unsafeSubscribeFn(new Subscriber[A] {
implicit val scheduler = out.scheduler
private[this] var isEmpty = true
private[this] var isDone = false
private[this] var ack: Future[Ack] = Continue
def onNext(elem: A): Future[Ack] = {
if (isEmpty) isEmpty = false
ack = out.onNext(elem)
ack
}
def onError(ex: Throwable): Unit =
if (!isDone) {
isDone = true
out.onError(ex)
}
def onComplete(): Unit =
if (!isDone) {
isDone = true
// Creating an asynchronous boundary, otherwise we might
// blow up the stack.
if (!isEmpty) ack.onComplete {
case Success(Continue) =>
loop(subject, out, task, index + 1)
case _ =>
() // do nothing
}
else {
out.onComplete()
}
}
})
// We need to do an `orderedUpdate`, because `onComplete` might have
// already executed and we might be resubscribed by now.
task.orderedUpdate(cancelable, index)
}
def unsafeSubscribeFn(out: Subscriber[A]): Cancelable = {
val subject = ReplaySubject[A]()
val repeatTask = OrderedCancelable()
loop(subject, out, repeatTask, index = 0)
val mainTask = source.unsafeSubscribeFn(Subscriber(subject, out.scheduler))
CompositeCancelable(mainTask, repeatTask)
}
}