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TarReaderStage only pull when needed, #2714 #2715

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merged 1 commit into from Aug 10, 2021
Merged

TarReaderStage only pull when needed, #2714 #2715

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37 changes: 22 additions & 15 deletions file/src/main/scala/akka/stream/alpakka/file/impl/archive/TarReaderStage.scala
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Expand Up @@ -42,7 +42,7 @@ private[file] class TarReaderStage
if (buffer.length >= TarArchiveEntry.headerLength) {
readFile(buffer)
} else {
if (!hasBeenPulled(flowIn)) pull(flowIn)
tryPullIfNeeded()
setHandlers(flowIn, flowOut, new CollectHeader(buffer))
}
}
Expand All @@ -51,7 +51,7 @@ private[file] class TarReaderStage
def pushSource(metadata: TarArchiveMetadata, buffer: ByteString): Unit = {
if (buffer.length >= metadata.size) {
val (emit, remain) = buffer.splitAt(metadata.size.toInt)
log.debug(s"emitting completed source for $metadata")
log.debug("emitting completed source for [{}]", metadata)
push(flowOut, metadata -> Source.single(emit))
readTrailer(metadata, remain, subSource = None)
} else setHandlers(flowIn, flowOut, new CollectFile(metadata, buffer))
Expand Down Expand Up @@ -117,13 +117,18 @@ private[file] class TarReaderStage
case WarnTermination =>
log.warning(
"The tar content source was not subscribed to within {}, it must be subscribed to to progress tar file reading.",
timeout
timeout.toCoarsest
)
case NoopTermination =>
}
}
}

private def tryPullIfNeeded(): Unit = {
if (!hasBeenPulled(flowIn))
tryPull(flowIn)
}

/**
* Don't react on downstream pulls until we have something to push.
*/
Expand All @@ -137,7 +142,7 @@ private[file] class TarReaderStage
*/
private trait ExpectDownstreamPull extends OutHandler {
final override def onPull(): Unit = {
pull(flowIn)
tryPullIfNeeded()
setHandler(flowOut, IgnoreDownstreamPull)
}
}
Expand All @@ -152,7 +157,9 @@ private[file] class TarReaderStage
buffer ++= grab(flowIn)
if (buffer.length >= TarArchiveEntry.headerLength) {
readFile(buffer)
} else pull(flowIn)
} else {
tryPullIfNeeded()
}
}

override def onUpstreamFinish(): Unit = {
Expand All @@ -173,7 +180,6 @@ private[file] class TarReaderStage
extends InHandler
with IgnoreDownstreamPull {
private var emitted: Long = 0
private var flowInPulled = false

private val subSource: FileOutSubSource = {
val sub = new FileOutSubSource()
Expand All @@ -185,9 +191,8 @@ private[file] class TarReaderStage
subPush(buffer)
buffer = ByteString.empty
if (isClosed(flowIn)) onUpstreamFinish()
} else if (!flowInPulled) {
flowInPulled = true
pull(flowIn)
} else {
tryPullIfNeeded()
}
}
})
Expand All @@ -196,7 +201,7 @@ private[file] class TarReaderStage
sub
}

log.debug(s"emitting source for $metadata")
log.debug("emitting source for [{}]", metadata)
push(flowOut, metadata -> Source.fromGraph(subSource.source))
setHandler(flowOut, IgnoreDownstreamPull)

Expand All @@ -213,7 +218,6 @@ private[file] class TarReaderStage
}

override def onPush(): Unit = {
flowInPulled = false
subPush(grab(flowIn))
}

Expand Down Expand Up @@ -246,10 +250,13 @@ private[file] class TarReaderStage
subSource.foreach { src =>
src.complete()
setHandler(flowOut, ExpectDownstreamPull)
if (isAvailable(flowOut)) pull(flowIn)
if (isAvailable(flowOut))
tryPullIfNeeded()
}
readHeader(buffer.drop(trailerLength))
} else pull(flowIn)
} else {
tryPullIfNeeded()
}
}

override def onUpstreamFinish(): Unit = {
Expand All @@ -270,10 +277,10 @@ private[file] class TarReaderStage

override def onPush(): Unit = {
grab(flowIn)
pull(flowIn)
tryPullIfNeeded()
}

tryPull(flowIn)
tryPullIfNeeded()
}

}
Expand Down