TextMapPropagator draft #124
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| @@ -67,6 +68,7 @@ lazy val `core-common` = crossProject(JVMPlatform, JSPlatform, NativePlatform) | |||
| name := "otel4s-core-common", | |||
| libraryDependencies ++= Seq( | |||
| "org.typelevel" %%% "cats-core" % CatsVersion, | |||
| "org.typelevel" %%% "vault" % VaultVersion, | |||
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This has been stable for a long time, but it's not strictly necessary. It turns out to be a very good match for the Otel spec.
| import cats.effect.kernel.Unique | ||
| import org.typelevel.vault | ||
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| sealed trait Context { |
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This is easy enough, but we need an isomorphism with the Java one to wrap their propagators, and that's where it turns to mush.
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We can maybe do a type parameter and some Aux magic and drop the Vault dependency? (Vault would still be ideal for a pure Scala implementation, but I'm not going there anytime soon...) But then I'm not sure how we'd create and reference keys in the core.
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| trait TextMapPropagator[F[_]] extends TextMapInjector[F] with TextMapExtractor | ||
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| trait TextMapInjector[F[_]] { |
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On the extractor side, we are to return a new immutable Context, so it's pure. No such constraint is given for injection, and the Java one returns Unit.
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| trait TextMapGetter[A] { | ||
| def keys(carrier: A): List[String] | ||
| def get(carrier: A, key: String): Option[A] |
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@zmccoy and I had a workplace accident this week relating to this being case sensitive, but it's not clear that the spec supports case insensitivity for all transports.
| dispatcher.unsafeRunSync( | ||
| Functor[F].void(setter.set(carrier, key, value)) | ||
| ) |
| def get[A](key: JContextKey[A]): A = | ||
| context.get(key) match { | ||
| case Some(a) => a | ||
| case None => null.asInstanceOf[A] |
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Useful thought exercise, but a dead end. |
Fixes #123