// JoinOrNew creates a new Span joined to the provided DelegatingCarrier or
// creates Span from the given tracer.
func JoinOrNew(tr opentracing.Tracer, carrier *Span, opName string) (opentracing.Span, error) {
if carrier != nil {
sp, err := tr.Join(opName, basictracer.Delegator, carrier)
switch err {
case nil:
sp.LogEvent(opName)
return sp, nil
case opentracing.ErrTraceNotFound:
default:
return nil, err
}
}
return tr.StartSpan(opName), nil
}
func TestTracer(t *testing.T) {
log.SetFlags(0)
var tracer ot.Tracer
tracer = &Tracer{}
ot.InitGlobalTracer(tracer)
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
serverSpan, err := tracer.Join(
"serverSpan",
ot.TextMap,
ot.HTTPHeaderTextMapCarrier(r.Header))
if err != nil {
panic(err)
}
time.Sleep(time.Second * 1)
serverSpan.Finish()
fmt.Fprintln(w, "Hello, client")
}))
defer ts.Close()
span, nctx := ot.StartSpanFromContext(context.TODO(), "main_test")
defer span.Finish()
foo(nctx, "bar", 0)
httpClient := &http.Client{}
httpReq, _ := http.NewRequest("GET", ts.URL, nil)
// Transmit the span's TraceContext as HTTP headers on our
// outbound request.
tracer.Inject(
span,
ot.TextMap,
ot.HTTPHeaderTextMapCarrier(httpReq.Header))
if _, err := httpClient.Do(httpReq); err != nil {
panic(err)
}
}