Change record interface to include WithMeter option, per @rghetia

stats/record.go

@@ -31,19 +31,17 @@ func init() {
 	}
 }
 
-// ResolvedOptions can be used to extract the current tags and measurements
-// from context and stats arguments when using custom workers to export stats
-// to a separate exporter.
-type ResolvedOptions struct {
-	Attachments metricdata.Attachments
-	Tags        *tag.Map
-	Measures    []Measurement
+// Recorder is a subset of the view.Meter interface which only includes
+// the Record method, to avoid circular imports between stats and view.
+type Recorder interface {
+	Record(*tag.Map, interface{}, map[string]interface{})
 }
 
 type recordOptions struct {
 	attachments  metricdata.Attachments
 	mutators     []tag.Mutator
 	measurements []Measurement
+	recorder     Recorder
 }
 
 // WithAttachments applies provided exemplar attachments.
@@ -67,6 +65,14 @@ func WithMeasurements(measurements ...Measurement) Options {
 	}
 }
 
+// WithMeter records the measurements to the specified `view.Meter`, rather
+// than to the global metrics recorder.
+func WithMeter(meter Recorder) Options {
+	return func(ro *recordOptions) {
+		ro.recorder = meter
+	}
+}
+
 // Options apply changes to recordOptions.
 type Options func(*recordOptions)
 
@@ -93,23 +99,6 @@ func RecordWithTags(ctx context.Context, mutators []tag.Mutator, ms ...Measureme
 	return RecordWithOptions(ctx, WithTags(mutators...), WithMeasurements(ms...))
 }
 
-// ResolveOptions determines the full set of Tags, Measurements, etc from the
-// provided Options and context.Context. This is mostly useful when using
-// multiple exporters.
-func ResolveOptions(ctx context.Context, ros ...Options) (*ResolvedOptions, error) {
-	o := createRecordOption(ros...)
-
-	if len(o.mutators) > 0 {
-		var err error
-		if ctx, err = tag.New(ctx, o.mutators...); err != nil {
-			return nil, err
-		}
-	}
-	return &ResolvedOptions{Tags: tag.FromContext(ctx),
-		Measures:    o.measurements,
-		Attachments: o.attachments}, nil
-}
-
 // RecordWithOptions records measurements from the given options (if any) against context
 // and tags and attachments in the options (if any).
 // If there are any tags in the context, measurements will be tagged with them.
@@ -118,9 +107,10 @@ func RecordWithOptions(ctx context.Context, ros ...Options) error {
 	if len(o.measurements) == 0 {
 		return nil
 	}
-	// This could use ResolveOptions, but it does additional work to
-	// short-circuit if there are no metrics that need to be exported.
 	recorder := internal.DefaultRecorder
+	if o.recorder != nil {
+		recorder = o.recorder.Record
+	}
 	if recorder == nil {
 		return nil
 	}

stats/record_test.go

@@ -96,6 +96,8 @@ func cmpExemplar(got, want *metricdata.Exemplar) string {
 }
 
 func TestResolveOptions(t *testing.T) {
+	meter := view.NewWorker()
+	meter.Start()
 	k1 := tag.MustNewKey("k1")
 	k2 := tag.MustNewKey("k2")
 	m1 := stats.Int64("TestResolveOptions/m1", "", stats.UnitDimensionless)
@@ -111,48 +113,88 @@ func TestResolveOptions(t *testing.T) {
 		Measure:     m2,
 		Aggregation: view.Count(),
 	}}
-	view.SetReportingPeriod(100 * time.Millisecond)
-	if err := view.Register(v...); err != nil {
+	meter.SetReportingPeriod(100 * time.Millisecond)
+	if err := meter.Register(v...); err != nil {
 		t.Fatalf("Failed to register view: %v", err)
 	}
-	defer view.Unregister(v...)
+	defer meter.Unregister(v...)
 
 	attachments := map[string]interface{}{metricdata.AttachmentKeySpanContext: spanCtx}
 	ctx, err := tag.New(context.Background(), tag.Insert(k1, "foo"), tag.Insert(k2, "foo"))
 	if err != nil {
 		t.Fatalf("Failed to set context: %v", err)
 	}
-	ro, err := stats.ResolveOptions(ctx,
+	err = stats.RecordWithOptions(ctx,
 		stats.WithTags(tag.Upsert(k1, "bar"), tag.Insert(k2, "bar")),
 		stats.WithAttachments(attachments),
-		stats.WithMeasurements(m1.M(12), m2.M(5)))
+		stats.WithMeasurements(m1.M(12), m1.M(6), m2.M(5)),
+		stats.WithMeter(meter))
 	if err != nil {
 		t.Fatalf("Failed to resolve data point: %v", err)
 	}
 
-	s, ok := ro.Attachments[metricdata.AttachmentKeySpanContext]
-	if !ok || s != spanCtx {
-		t.Errorf("Unexpected SpanContext: want %v, got %v", spanCtx, s)
+	rows, err := meter.RetrieveData("test_view")
+	if err != nil {
+		t.Fatalf("Unable to retrieve data for test_view: %v", err)
 	}
-	if len(ro.Attachments) != 1 {
-		t.Errorf("Expected only one attachment (SpanContext), got %v", ro.Attachments)
+	if len(rows) != 1 {
+		t.Fatalf("Expected one row, got %d rows: %+v", len(rows), rows)
 	}
+	if len(rows[0].Tags) != 2 {
+		t.Errorf("Wrong number of tags %d: %v", len(rows[0].Tags), rows[0].Tags)
+	}
+	// k2 was Insert() ed, and shouldn't update the value that was in the supplied context.
+	wantTags := []tag.Tag{{Key: k1, Value: "bar"}, {Key: k2, Value: "foo"}}
+	for i, tag := range rows[0].Tags {
+		if tag.Key != wantTags[i].Key {
+			t.Errorf("Incorrect tag %d, want: %q, got: %q", i, wantTags[i].Key, tag.Key)
+		}
+		if tag.Value != wantTags[i].Value {
+			t.Errorf("Incorrect tag for %s, want: %q, got: %v", tag.Key, wantTags[i].Value, tag.Value)
+		}
 
-	if len(ro.Measures) != 2 {
-		t.Errorf("Expected two measurements, got %v", ro.Measures)
 	}
-	mWant := []stats.Measurement{m1.M(12), m2.M(5)}
-	if ro.Measures[0] != mWant[0] || ro.Measures[1] != mWant[1] {
-		t.Errorf("Unexpected measurements: want %v, got %v", mWant, ro.Measures)
+	wantBuckets := []int64{0, 1, 1}
+	gotBuckets := rows[0].Data.(*view.DistributionData)
+	if !reflect.DeepEqual(gotBuckets.CountPerBucket, wantBuckets) {
+		t.Fatalf("want buckets %v, got %v", wantBuckets, gotBuckets)
+	}
+	for i, e := range gotBuckets.ExemplarsPerBucket {
+		if gotBuckets.CountPerBucket[i] == 0 {
+			if e != nil {
+				t.Errorf("Unexpected exemplar for bucket")
+			}
+			continue
+		}
+		// values from the metrics above
+		exemplarValues := []float64{0, 6, 12}
+		wantExemplar := &metricdata.Exemplar{Value: exemplarValues[i], Attachments: attachments}
+		if diff := cmpExemplar(e, wantExemplar); diff != "" {
+			t.Errorf("Bad exemplar for %d: %+v", i, diff)
+		}
 	}
 
-	// k2 was Insert() ed, and shouldn't update the value that was in the supplied context.
-	tCtx, err := tag.New(context.Background(), tag.Insert(k1, "bar"), tag.Insert(k2, "foo"))
+	rows2, err := meter.RetrieveData("second_view")
 	if err != nil {
-		t.Fatalf("Failed to construct tWant: %v", err)
+		t.Fatalf("Failed to read second_view: %v", err)
+	}
+	if len(rows2) != 1 {
+		t.Fatalf("Expected one row, got %d rows: %v", len(rows2), rows2)
+	}
+	if len(rows2[0].Tags) != 1 {
+		t.Errorf("Expected one tag, got %d tags: %v", len(rows2[0].Tags), rows2[0].Tags)
+	}
+	wantTags = []tag.Tag{{Key: k1, Value: "bar"}}
+	for i, tag := range rows2[0].Tags {
+		if wantTags[i].Key != tag.Key {
+			t.Errorf("Wrong key for %d, want %q, got %q", i, wantTags[i].Key, tag.Key)
+		}
+		if wantTags[i].Value != tag.Value {
+			t.Errorf("Wrong value for tag %s, want %q got %q", tag.Key, wantTags[i].Value, tag.Value)
+		}
 	}
-	tWant := tag.FromContext(tCtx)
-	if ro.Tags.String() != tWant.String() {
-		t.Errorf("Unexpected tags: want %v, got %v", tWant, ro.Tags)
+	gotCount := rows2[0].Data.(*view.CountData)
+	if gotCount.Value != 1 {
+		t.Errorf("Wrong count for second_view, want %d, got %d", 1, gotCount.Value)
 	}
 }

stats/view/worker.go

@@ -61,7 +61,7 @@ type worker struct {
 // module should cover the common use cases.
 type Meter interface {
 	// Record records a set of measurements ms associated with the given tags and attachments.
-	Record(tags *tag.Map, ms []stats.Measurement, attachments map[string]interface{})
+	Record(tags *tag.Map, ms interface{}, attachments map[string]interface{})
 	// Find returns a registered view associated with this name.
 	// If no registered view is found, nil is returned.
 	Find(name string) *View
@@ -98,6 +98,10 @@ type Meter interface {
 	Start()
 	// Stop causes the Meter to stop processing calls and terminate data export.
 	Stop()
+
+	// RetrieveData gets a snapshot of the data collected for the the view registered
+	// with the given name. It is intended for testing only.
+	RetrieveData(viewName string) ([]*Row, error)
 }
 
 var _ Meter = (*worker)(nil)
@@ -169,10 +173,12 @@ func (w *worker) Unregister(views ...*View) {
 // RetrieveData gets a snapshot of the data collected for the the view registered
 // with the given name. It is intended for testing only.
 func RetrieveData(viewName string) ([]*Row, error) {
-	return defaultWorker.retrieveData(viewName)
+	return defaultWorker.RetrieveData(viewName)
 }
 
-func (w *worker) retrieveData(viewName string) ([]*Row, error) {
+// RetrieveData gets a snapshot of the data collected for the the view registered
+// with the given name. It is intended for testing only.
+func (w *worker) RetrieveData(viewName string) ([]*Row, error) {
 	req := &retrieveDataReq{
 		now: time.Now(),
 		v:   viewName,
@@ -184,14 +190,14 @@ func (w *worker) retrieveData(viewName string) ([]*Row, error) {
 }
 
 func record(tags *tag.Map, ms interface{}, attachments map[string]interface{}) {
-	defaultWorker.Record(tags, ms.([]stats.Measurement), attachments)
+	defaultWorker.Record(tags, ms, attachments)
 }
 
 // Record records a set of measurements ms associated with the given tags and attachments.
-func (w *worker) Record(tags *tag.Map, ms []stats.Measurement, attachments map[string]interface{}) {
+func (w *worker) Record(tags *tag.Map, ms interface{}, attachments map[string]interface{}) {
 	req := &recordReq{
 		tm:          tags,
-		ms:          ms,
+		ms:          ms.([]stats.Measurement),
 		attachments: attachments,
 		t:           time.Now(),
 	}

stats/view/worker_test.go

@@ -187,7 +187,7 @@ func Test_Worker_MultiExport(t *testing.T) {
 	for _, wantRow := range wantRows {
 		retrieve := RetrieveData
 		if wantRow.w != nil {
-			retrieve = wantRow.w.(*worker).retrieveData
+			retrieve = wantRow.w.(*worker).RetrieveData
 		}
 		gotRows, err := retrieve(wantRow.view)
 		if err != nil {
@@ -207,7 +207,7 @@ func Test_Worker_MultiExport(t *testing.T) {
 		}
 	}
 	// Verify that worker has not been computing sum:
-	got, err := worker2.retrieveData(sum.Name)
+	got, err := worker2.RetrieveData(sum.Name)
 	if err == nil {
 		t.Errorf("%s: expected no data because it was not registered, got %#v", sum.Name, got)
 	}