swarm/spancontext/spancontext.go


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package spancontext

import (
    "context"

    opentracing "github.com/opentracing/opentracing-go"
)

func WithContext(ctx context.Context, sctx opentracing.SpanContext) context.Context {
    return context.WithValue(ctx, "span_context", sctx)
}

func FromContext(ctx context.Context) opentracing.SpanContext {
    sctx, ok := ctx.Value("span_context").(opentracing.SpanContext)
    if ok {
        return sctx
    }

    return nil
}

func StartSpan(ctx context.Context, name string) (context.Context, opentracing.Span) {
    tracer := opentracing.GlobalTracer()

    sctx := FromContext(ctx)

    var sp opentracing.Span
    if sctx != nil {
        sp = tracer.StartSpan(
            name,
            opentracing.ChildOf(sctx))
    } else {
        sp = tracer.StartSpan(name)
    }

    nctx := context.WithValue(ctx, "span_context", sp.Context())

    return nctx, sp
}

func StartSpanFrom(name string, sctx opentracing.SpanContext) opentracing.Span {
    tracer := opentracing.GlobalTracer()

    sp := tracer.StartSpan(
        name,
        opentracing.ChildOf(sctx))

    return sp
}