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Fix a bug in viaMat for Identity flow optimization #22899

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Richard Imaoka 2017-11-13 17:21:46 +09:00 • committed by Johan Andrén
parent cba1cb79fa
commit ad5fa124b3
2 changed files with 36 additions and 9 deletions
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24
akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala
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@ -45,15 +45,23 @@ final class Source[+Out, +Mat](
override def via[T, Mat2](flow: Graph[FlowShape[Out, T], Mat2]): Repr[T] = viaMat(flow)(Keep.left)
override def viaMat[T, Mat2, Mat3](flow: Graph[FlowShape[Out, T], Mat2])(combine: (Mat, Mat2) ⇒ Mat3): Source[T, Mat3] = {
val toAppend =
if (flow.traversalBuilder eq Flow.identityTraversalBuilder)
LinearTraversalBuilder.empty()
if (flow.traversalBuilder eq Flow.identityTraversalBuilder)
if (combine == Keep.left)
//optimization by returning this
this.asInstanceOf[Source[T, Mat3]] //Mat == Mat3, due to Keep.left
else if (combine == Keep.right || combine == Keep.none) // Mat3 = NotUsed
//optimization with LinearTraversalBuilder.empty()
new Source[T, Mat3](
traversalBuilder.append(LinearTraversalBuilder.empty(), flow.shape, combine),
SourceShape(shape.out).asInstanceOf[SourceShape[T]])
else
flow.traversalBuilder
new Source[T, Mat3](
traversalBuilder.append(toAppend, flow.shape, combine),
SourceShape(flow.shape.out))
new Source[T, Mat3](
traversalBuilder.append(flow.traversalBuilder, flow.shape, combine),
SourceShape(flow.shape.out))
else
new Source[T, Mat3](
traversalBuilder.append(flow.traversalBuilder, flow.shape, combine),
SourceShape(flow.shape.out))
}
/**