62 lines
1.8 KiB
Scala
62 lines
1.8 KiB
Scala
package docs.stream.cookbook
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import java.security.MessageDigest
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import akka.stream.scaladsl.{ Sink, Source }
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import akka.util.ByteString
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import scala.concurrent.Await
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import scala.concurrent.duration._
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class RecipeDigest extends RecipeSpec {
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"Recipe for calculating digest" must {
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"work" in {
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val data = Source(List(
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ByteString("abcdbcdecdef"),
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ByteString("defgefghfghighijhijkijkljklmklmnlmnomnopnopq")))
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//#calculating-digest
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import akka.stream.stage._
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def digestCalculator(algorithm: String) = new PushPullStage[ByteString, ByteString] {
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val digest = MessageDigest.getInstance(algorithm)
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override def onPush(chunk: ByteString, ctx: Context[ByteString]): Directive = {
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digest.update(chunk.toArray)
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ctx.pull()
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}
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override def onPull(ctx: Context[ByteString]): Directive = {
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if (ctx.isFinishing) ctx.pushAndFinish(ByteString(digest.digest()))
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else ctx.pull()
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}
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override def onUpstreamFinish(ctx: Context[ByteString]): TerminationDirective = {
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// If the stream is finished, we need to emit the last element in the onPull block.
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// It is not allowed to directly emit elements from a termination block
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// (onUpstreamFinish or onUpstreamFailure)
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ctx.absorbTermination()
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}
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}
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val digest: Source[ByteString, Unit] = data.transform(() => digestCalculator("SHA-256"))
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//#calculating-digest
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Await.result(digest.runWith(Sink.head()), 3.seconds) should be(
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ByteString(
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0x24, 0x8d, 0x6a, 0x61,
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0xd2, 0x06, 0x38, 0xb8,
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0xe5, 0xc0, 0x26, 0x93,
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0x0c, 0x3e, 0x60, 0x39,
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0xa3, 0x3c, 0xe4, 0x59,
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0x64, 0xff, 0x21, 0x67,
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0xf6, 0xec, 0xed, 0xd4,
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0x19, 0xdb, 0x06, 0xc1))
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}
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}
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}
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