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Fixes eager observe that was causing early cleanup of resources. #1106

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merged 1 commit into from
Mar 12, 2018
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Fixes eager observe that was causing early cleanup of resources. #1106

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22 changes: 22 additions & 0 deletions core/jvm/src/test/scala/fs2/PipeSpec.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -511,6 +511,28 @@ class PipeSpec extends Fs2Spec {
out2.map(_.toLong).sum shouldBe sum.get
}
}

"observe is not eager (1)" in {
//Do not pull another element before we emit the currently processed one
(Stream.eval(IO(1)) ++ Stream.eval(IO.raiseError(new Throwable("Boom"))))
.observe(_.evalMap(_ => IO(Thread.sleep(100)))) //Have to do some work here, so that we give time for the underlying stream to try pull more
.take(1)
.compile
.toVector
.unsafeRunSync shouldBe Vector(1)
}

"observe is not eager (2)" in {
//Do not pull another element before the downstream asks for another
(Stream.eval(IO(1)) ++ Stream.eval(IO.raiseError(new Throwable("Boom"))))
.observe(_.drain)
.flatMap(_ => Stream.eval(IO(Thread.sleep(100))) >> Stream(1, 2)) //Have to do some work here, so that we give time for the underlying stream to try pull more
.take(2)
.compile
.toVector
.unsafeRunSync shouldBe Vector(1, 2)
}

}
"handle errors from observing sink" in {
forAll { (s: PureStream[Int]) =>
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10 changes: 5 additions & 5 deletions core/shared/src/main/scala/fs2/Stream.scala
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Expand Up @@ -2185,14 +2185,14 @@ object Stream {
/** Send chunks through `sink`, allowing up to `maxQueued` pending _segments_ before blocking `s`. */
def observeAsync(maxQueued: Int)(sink: Sink[F, O])(implicit F: Effect[F],
ec: ExecutionContext): Stream[F, O] =
Stream.eval(async.semaphore[F](maxQueued)).flatMap { guard =>
Stream.eval(async.semaphore[F](maxQueued - 1)).flatMap { guard =>
Stream.eval(async.unboundedQueue[F, Option[Segment[O, Unit]]]).flatMap { outQ =>
Stream.eval(async.unboundedQueue[F, Option[Segment[O, Unit]]]).flatMap { sinkQ =>
val inputStream =
self.segments.noneTerminate.evalMap {
case Some(segment) =>
guard.decrement >>
sinkQ.enqueue1(Some(segment))
sinkQ.enqueue1(Some(segment)) >>
guard.decrement

case None =>
sinkQ.enqueue1(None)
Expand All @@ -2214,8 +2214,8 @@ object Stream {
val outputStream =
outQ.dequeue.unNoneTerminate
.flatMap { segment =>
Stream.eval(guard.increment) >>
Stream.segment(segment)
Stream.segment(segment) ++
Stream.eval_(guard.increment)
}

outputStream.concurrently(runner)
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