swarm/tracing: Add context key constants

swarm/network/stream/delivery.go

@@ -275,8 +275,8 @@ func (d *Delivery) RequestFromPeers(ctx context.Context, req *network.Request) (
 
 	// setting this value in the context creates a new span that can persist across the sendpriority queue and the network roundtrip
 	// this span will finish only when delivery is handled (or times out)
-	ctx = context.WithValue(ctx, "stream_send_tag", "stream.send.request")
-	ctx = context.WithValue(ctx, "stream_send_meta", fmt.Sprintf("%v.%v", sp.ID(), req.Addr))
+	ctx = context.WithValue(ctx, tracing.StoreLabelId, "stream.send.request")
+	ctx = context.WithValue(ctx, tracing.StoreLabelMeta, fmt.Sprintf("%v.%v", sp.ID(), req.Addr))
 	err := sp.SendPriority(ctx, &RetrieveRequestMsg{
 		Addr:      req.Addr,
 		SkipCheck: req.SkipCheck,

swarm/tracing/tracing.go

@@ -23,7 +23,11 @@ var (
 )
 
 // TracingEnabledFlag is the CLI flag name to use to enable trace collections.
-const TracingEnabledFlag = "tracing"
+const (
+	TracingEnabledFlag = "tracing"
+	StoreLabelId       = "span_save_id"
+	StoreLabelMeta     = "span_save_meta"
+)
 
 var (
 	Closer io.Closer
@@ -117,19 +121,20 @@ func StartSaveSpan(ctx context.Context) context.Context {
 	if !Enabled {
 		return ctx
 	}
-	traceId := ctx.Value("span_save_id")
+	traceId := ctx.Value(StoreLabelId)
+
 	if traceId != nil {
 		traceStr := traceId.(string)
 		var sp opentracing.Span
 		ctx, sp = spancontext.StartSpan(
 			ctx,
 			traceStr,
 		)
-		traceMeta := ctx.Value("span_save_meta")
+		traceMeta := ctx.Value(StoreLabelMeta)
 		if traceMeta != nil {
 			traceStr = traceStr + "." + traceMeta.(string)
 		}
-		store.spans.Store(traceId, sp)
+		store.spans.Store(traceStr, sp)
 	}
 	return ctx
 }