Allow HttpTraceContext to accept a SpanContext

[diehard2]

I'm not using global contexts in my application. Instead I'm passing SpanContexts and creating children manually. My code has a lot of threads, and its easier to keep track of how everything is hooking up this way. This is all working extremely well until I need to propagate my latest span context. The Inject method in HttpTraceContext only takes a Context, which it immediately makes into a SpanContext.

  void Inject(context::propagation::TextMapCarrier &carrier,
              const context::Context &context) noexcept override
  {
    SpanContext span_context = trace::GetSpan(context)->GetContext();
    if (!span_context.IsValid())
    {
      return;
    }
    InjectImpl(carrier, span_context);
  }

1. Would it be possible to supply a constructor that takes a SpanContext for those of us who are doing this more manually?
2. Alternatively, is there a way to make a Context from a SpanContext. I couldn't find an easy way to do this

I know I can copy that file and change it to suit my needs, but ideally there would be a way around that. Thanks for any help.

[marcalff]

Thanks for the report.

See the related issue:

• [Trace API] TextMapPropagator requires to use RuntimeContext #1467

[marcalff]

As indicated previously with the related issue, the solution is:

opentelemetry::context::Context empty;
auto wrapped_span_context = SetSpan(empty, span);

propagator.Inject(carrier, wrapped_span_context);

Closing this report.