sdk/trace: ParentBased is a decorator

[pellared]

From open-telemetry/opentelemetry.io@5847bd3#r128534150

Update the docs and describe ParentBased sampler as a decorator (not composite).

[pellared]

We should update the specification first https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#parentbased

[pellared]

I created open-telemetry/opentelemetry-specification#3706

[MrAlias]

Huh? It is literally a decision hierarchy tree that determines what sampler to use.

opentelemetry-go/sdk/trace/sampling.go

Lines 266 to 282 in 1410496

	func (pb parentBased) ShouldSample(p SamplingParameters) SamplingResult {
	psc := trace.SpanContextFromContext(p.ParentContext)
	if psc.IsValid() {
	if psc.IsRemote() {
	if psc.IsSampled() {
	return pb.config.remoteParentSampled.ShouldSample(p)
	}
	return pb.config.remoteParentNotSampled.ShouldSample(p)
	}
	if psc.IsSampled() {
	return pb.config.localParentSampled.ShouldSample(p)
	}
	return pb.config.localParentNotSampled.ShouldSample(p)
	}
	return pb.root.ShouldSample(p)
	}

Also Go is not an object-oriented language, I do not support including object-oriented terms in our descriptions.

[pellared]

I do not support including object-oriented terms in our descriptions

Even though GoF design patterns are coming from object-oriented languages (C++ and Smalltalk), Go is quite close to these languages (at least a lot closer than to functional languages). Even though there are key differences they are not related to the GoF design patterns which can be applied.

PS. I would prefer using a more Go idiomatic term instead but I am not aware if such exist.
PS2. https://go.dev/doc/faq#Is_Go_an_object-oriented_language