monix.reactive.internal.operators.WhileBusyDropEventsAndSignalOperator.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
import monix.execution.Ack.{Continue, Stop}
import scala.util.control.NonFatal
import monix.reactive.Observable.Operator
import monix.reactive.observers.Subscriber
import scala.concurrent.Future
private[reactive] final class WhileBusyDropEventsAndSignalOperator[A](onOverflow: Long => A) extends Operator[A, A] {
def apply(out: Subscriber[A]): Subscriber.Sync[A] =
new Subscriber.Sync[A] {
implicit val scheduler = out.scheduler
private[this] var ack = Continue: Future[Ack]
private[this] var eventsDropped = 0L
private[this] var isDone = false
def onNext(elem: A) =
if (isDone) Stop
else
ack.syncTryFlatten match {
case Continue =>
// Protects calls to user code from within the operator and
// stream the error downstream if it happens, but if the
// error happens because of calls to `onNext` or other
// protocol calls, then the behavior should be undefined.
var streamError = true
val hasOverflow = eventsDropped > 0
try {
if (hasOverflow) {
val message = onOverflow(eventsDropped)
eventsDropped = 0
streamError = false
ack = out.onNext(message)
onNext(elem) // retry, recursive call, take care!
} else {
streamError = false
ack = out.onNext(elem)
if (ack eq Stop) Stop else Continue
}
} catch {
case NonFatal(ex) if streamError =>
onError(ex)
Stop
}
case Stop => Stop
case async =>
eventsDropped += 1
Continue
}
def onError(ex: Throwable) =
if (!isDone) {
isDone = true
out.onError(ex)
}
def onComplete() =
if (!isDone) {
isDone = true
val hasOverflow = eventsDropped > 0
if (!hasOverflow)
out.onComplete()
else
ack.syncOnContinue {
// Protects calls to user code from within the operator and
// stream the error downstream if it happens, but if the
// error happens because of calls to `onNext` or other
// protocol calls, then the behavior should be undefined.
var streamError = true
try {
val message = onOverflow(eventsDropped)
streamError = false
out.onNext(message)
out.onComplete()
} catch {
case NonFatal(ex) if streamError =>
out.onError(ex)
}
}
}
}
}