Repro Stackdriver span Link issue (googleapis#690) (googleapis#692)

exporter/stackdriver/stackdriver.go

@@ -25,6 +25,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log"
 	"time"
 
 	traceapi "cloud.google.com/go/trace/apiv2"
@@ -135,3 +136,11 @@ func (e *Exporter) Flush() {
 	e.statsExporter.Flush()
 	e.traceExporter.Flush()
 }
+
+func (o Options) handleError(err error) {
+	if o.OnError != nil {
+		o.OnError(err)
+		return
+	}
+	log.Printf("Error exporting to Stackdriver: %v", err)
+}

exporter/stackdriver/stackdriver_test.go

@@ -36,7 +36,11 @@ func TestExport(t *testing.T) {
 		t.Skip("STACKDRIVER_TEST_PROJECT_ID not set")
 	}
 
-	exporter, err := NewExporter(Options{ProjectID: projectID})
+	var exportErrors []error
+
+	exporter, err := NewExporter(Options{ProjectID: projectID, OnError: func(err error) {
+		exportErrors = append(exportErrors, err)
+	}})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -56,7 +60,16 @@ func TestExport(t *testing.T) {
 	// Test HTTP spans
 
 	handler := http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+
+		_, backgroundSpan := trace.StartSpan(context.Background(), "BackgroundWork")
+		spanContext := backgroundSpan.SpanContext()
+		time.Sleep(10 * time.Millisecond)
+		backgroundSpan.End()
+
+		_, span := trace.StartSpan(req.Context(), "Sleep")
+		span.AddLink(trace.Link{Type: trace.LinkTypeChild, TraceID: spanContext.TraceID, SpanID: spanContext.SpanID})
 		time.Sleep(150 * time.Millisecond) // do work
+		span.End()
 		rw.Write([]byte("Hello, world!"))
 	})
 	server := httptest.NewServer(&ochttp.Handler{Handler: handler})
@@ -81,6 +94,10 @@ func TestExport(t *testing.T) {
 	// Flush twice to expose issue of exporter creating traces internally (#557)
 	exporter.Flush()
 	exporter.Flush()
+
+	for _, err := range exportErrors {
+		t.Error(err)
+	}
 }
 
 func TestGRPC(t *testing.T) {

exporter/stackdriver/stats.go

@@ -18,7 +18,6 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"log"
 	"os"
 	"path"
 	"strconv"
@@ -123,9 +122,9 @@ func (e *statsExporter) ExportView(vd *view.Data) {
 	case bundler.ErrOversizedItem:
 		go e.handleUpload(vd)
 	case bundler.ErrOverflow:
-		e.onError(errors.New("failed to upload: buffer full"))
+		e.o.handleError(errors.New("failed to upload: buffer full"))
 	default:
-		e.onError(err)
+		e.o.handleError(err)
 	}
 }
 
@@ -143,7 +142,7 @@ func getTaskValue() string {
 // of Data, as well as error handling.
 func (e *statsExporter) handleUpload(vds ...*view.Data) {
 	if err := e.uploadStats(vds); err != nil {
-		e.onError(err)
+		e.o.handleError(err)
 	}
 }
 
@@ -155,14 +154,6 @@ func (e *statsExporter) Flush() {
 	e.bundler.Flush()
 }
 
-func (e *statsExporter) onError(err error) {
-	if e.o.OnError != nil {
-		e.o.OnError(err)
-		return
-	}
-	log.Printf("Failed to export to Stackdriver Monitoring: %v", err)
-}
-
 func (e *statsExporter) uploadStats(vds []*view.Data) error {
 	span := trace.NewSpan(
 		"go.opencensus.io/exporter/stackdriver.uploadStats",

exporter/stackdriver/trace.go

@@ -31,6 +31,7 @@ import (
 // Stackdriver.
 //
 type traceExporter struct {
+	o         Options
 	projectID string
 	bundler   *bundler.Bundler
 	// uploadFn defaults to uploadSpans; it can be replaced for tests.
@@ -53,6 +54,7 @@ func newTraceExporterWithClient(o Options, c *tracingclient.Client) *traceExport
 	e := &traceExporter{
 		projectID: o.ProjectID,
 		client:    c,
+		o:         o,
 	}
 	bundler := bundler.NewBundler((*trace.SpanData)(nil), func(bundle interface{}) {
 		e.uploadFn(bundle.([]*trace.SpanData))
@@ -93,7 +95,7 @@ func (e *traceExporter) ExportSpan(s *trace.SpanData) {
 	case bundler.ErrOverflow:
 		e.overflowLogger.log()
 	default:
-		log.Println("OpenCensus Stackdriver exporter: failed to upload span:", err)
+		e.o.handleError(err)
 	}
 }
 
@@ -123,8 +125,7 @@ func (e *traceExporter) uploadSpans(spans []*trace.SpanData) {
 	err := e.client.BatchWriteSpans(ctx, &req)
 	if err != nil {
 		span.SetStatus(trace.Status{Code: 2, Message: err.Error()})
-		// TODO: Allow configuring a logger for exporters.
-		log.Printf("OpenCensus Stackdriver exporter: failed to upload %d spans: %v", len(spans), err)
+		e.o.handleError(err)
 	}
 }