initial import

core/trace/spancontext.go

@@ -0,0 +1,19 @@
+package trace
+
+type spanContext struct {
+	traceId string
+	spanId  string
+}
+
+func (sc spanContext) TraceId() string {
+	return sc.traceId
+}
+
+func (sc spanContext) SpanId() string {
+	return sc.spanId
+}
+
+func (sc spanContext) Visit(fn func(key, val string) bool) {
+	fn(traceIdKey, sc.traceId)
+	fn(spanIdKey, sc.spanId)
+}