Fixups after peer review

Signed-off-by: Andres Taylor <antaylor@squareup.com>

go/trace/trace.go

@@ -27,7 +27,6 @@ import (
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 	"vitess.io/vitess/go/vt/log"
-	"vitess.io/vitess/go/vt/proto/vtrpc"
 	"vitess.io/vitess/go/vt/sqlparser"
 	"vitess.io/vitess/go/vt/vterrors"
 )
@@ -132,21 +131,14 @@ var tracingBackendFactories = make(map[string]TracerFactory)
 var spanFactory TracingService = fakeSpanFactory{}
 
 var (
-	tracingServer = flag.String("tracer", "noop", "tracing service to use.")
+	tracingServer = flag.String("tracer", "noop", "tracing service to use")
 )
 
 // StartTracing enables tracing for a named service
 func StartTracing(serviceName string) io.Closer {
 	factory, ok := tracingBackendFactories[*tracingServer]
 	if !ok {
-		options := make([]string, len(tracingBackendFactories))
-		for k := range tracingBackendFactories {
-			options = append(options, k)
-		}
-
-		altStr := strings.Join(options, ", ")
-		log.Error(vterrors.Errorf(vtrpc.Code_INVALID_ARGUMENT, "no such tracing service found. alternatives are: %v", altStr))
-		return &nilCloser{}
+		return fail(serviceName)
 	}
 
 	tracer, closer, err := factory(serviceName)
@@ -159,3 +151,13 @@ func StartTracing(serviceName string) io.Closer {
 
 	return closer
 }
+
+func fail(serviceName string) io.Closer {
+	options := make([]string, len(tracingBackendFactories))
+	for k := range tracingBackendFactories {
+		options = append(options, k)
+	}
+	altStr := strings.Join(options, ", ")
+	log.Errorf("no such [%s] tracing service found. alternatives are: %v", serviceName, altStr)
+	return &nilCloser{}
+}

go/trace/trace_test.go

@@ -128,6 +128,7 @@ func (f *fakeTracer) Close() error {
 }
 
 func (f *fakeTracer) assertNoSpanWith(t *testing.T, substr string) {
+	t.Helper()
 	for _, logLine := range f.log {
 		if strings.Contains(logLine, substr) {
 			t.Fatalf("expected to not find [%v] but found it in [%v]", substr, logLine)
@@ -146,5 +147,3 @@ func (m *mockSpan) Finish() {
 func (m *mockSpan) Annotate(key string, value interface{}) {
 	m.tracer.log = append(m.tracer.log, fmt.Sprintf("key: %v values:%v", key, value))
 }
-
-

go/vt/worker/instance.go

@@ -131,7 +131,7 @@ func (wi *Instance) setAndStartWorker(ctx context.Context, wrk Worker, wr *wrang
 	go func() {
 		log.Infof("Starting worker...")
 		span, ctx := trace.NewSpan(wi.currentContext, "work")
-		span.Annotate("extra", wrk.StatusAsText())
+		span.Annotate("extra", wrk.State().String())
 		defer span.Finish()
 		var err error