pub fn extract_parent_into_current_span(headers: &HeaderMap)Expand description
Extract the parent OTel context from headers and attach it to the
current tracing::Span, so server-side spans share the dialer’s trace id.
A missing or malformed traceparent produces an empty context, which
set_parent accepts as a no-op — the local span just stays a root span.
Calling this from a #[tracing::instrument]’d handler must happen
before the first call to tracing::Span::context on the same span
(or anything that triggers a span entry that consults the parent), per
tracing-opentelemetry’s ordering contract. The two server-side
connect handlers wire it first thing in the function body for exactly
this reason.