Expose SpanFromContext

[zhezhel]

I'm working on integration pgx with Sentry.

The new version of pgx provides an interface for tracing, which work in the way when you need to implement two different methods: TraceQueryStart & TraceQueryEnd.

To implement TraceQueryEnd, I need to get access to span in context and call Finish on it.

It would be great to provide a method to get span from context.
Current workaround:

func SpanFromContext(ctx interface{}) (*sentry.Span, bool) {
	values := reflect.ValueOf(ctx).Elem()

	for i := 0; i < values.NumField(); i++ {
		reflectValue := values.Field(i)
		reflectValue = reflect.NewAt(reflectValue.Type(), unsafe.Pointer(reflectValue.UnsafeAddr())).Elem()
		span, ok := reflectValue.Interface().(*sentry.Span)
		if !ok {
			continue
		}
		return span, true
	}
	return nil, false
}

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (b551438) 80.56% compared to head (ba1e9b0) 80.56%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #672   +/-   ##
=======================================
  Coverage   80.56%   80.56%           
=======================================
  Files          44       44           
  Lines        4460     4460           
=======================================
  Hits         3593     3593           
  Misses        736      736           
  Partials      131      131           

Files Changed	Coverage Δ
tracing.go	85.95% <100.00%> (ø)

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[cleptric]

Works for me, @tonyo ?

[zhezhel]

Hey @cleptric, @tonyo, do you have plans to merge this PR?

[tonyo]

Yes, we do!