Allow creating additional View universes. (#1196)

* Allow creating additional View universes.

* Add methods to extract stats.Option

* Update with comments from @rghetia

* Change record interface to include WithMeter option, per @rghetia

* Update with feedback from @rghetia

Signed-off-by: Evan Anderson <evan.k.anderson@gmail.com>

* Add a benchmark for stats.WithMeter (but with no views registered)

Signed-off-by: Evan Anderson <evan.k.anderson@gmail.com>

* Stop the custom meter in test to prevent leaking goroutines.

stats/benchmark_test.go

@@ -19,6 +19,7 @@ import (
 	"testing"
 
 	"go.opencensus.io/stats"
+	"go.opencensus.io/stats/view"
 	_ "go.opencensus.io/stats/view" // enable collection
 	"go.opencensus.io/tag"
 )
@@ -52,6 +53,22 @@ func BenchmarkRecord8(b *testing.B) {
 	}
 }
 
+func BenchmarkRecord8_WithRecorder(b *testing.B) {
+	ctx := context.Background()
+	meter := view.NewMeter()
+	meter.Start()
+	defer meter.Stop()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		// Note that this benchmark has one extra allocation for stats.WithRecorder.
+		// If you cache the recorder option, this benchmark should be equally fast as BenchmarkRecord8
+		stats.RecordWithOptions(ctx, stats.WithRecorder(meter), stats.WithMeasurements(m.M(1), m.M(1), m.M(1), m.M(1), m.M(1), m.M(1), m.M(1), m.M(1)))
+	}
+
+	b.StopTimer()
+}
+
 func BenchmarkRecord8_Parallel(b *testing.B) {
 	ctx := context.Background()
 	b.ResetTimer()

stats/record.go

@@ -31,10 +31,19 @@ func init() {
 	}
 }
 
+// Recorder provides an interface for exporting measurement information from
+// the static Record method by using the WithRecorder option.
+type Recorder interface {
+	// Record records a set of measurements associated with the given tags and attachments.
+	// The second argument is a `[]Measurement`.
+	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.
@@ -58,6 +67,14 @@ func WithMeasurements(measurements ...Measurement) Options {
 	}
 }
 
+// WithRecorder records the measurements to the specified `Recorder`, rather
+// than to the global metrics recorder.
+func WithRecorder(meter Recorder) Options {
+	return func(ro *recordOptions) {
+		ro.recorder = meter
+	}
+}
+
 // Options apply changes to recordOptions.
 type Options func(*recordOptions)
 
@@ -93,6 +110,9 @@ func RecordWithOptions(ctx context.Context, ros ...Options) error {
 		return nil
 	}
 	recorder := internal.DefaultRecorder
+	if o.recorder != nil {
+		recorder = o.recorder.Record
+	}
 	if recorder == nil {
 		return nil
 	}

stats/record_test.go

@@ -56,6 +56,7 @@ func TestRecordWithAttachments(t *testing.T) {
 	if err := view.Register(v); err != nil {
 		log.Fatalf("Failed to register views: %v", err)
 	}
+	defer view.Unregister(v)
 
 	attachments := map[string]interface{}{metricdata.AttachmentKeySpanContext: spanCtx}
 	stats.RecordWithOptions(context.Background(), stats.WithAttachments(attachments), stats.WithMeasurements(m.M(12)))
@@ -93,3 +94,108 @@ func TestRecordWithAttachments(t *testing.T) {
 func cmpExemplar(got, want *metricdata.Exemplar) string {
 	return cmp.Diff(got, want, cmpopts.IgnoreFields(metricdata.Exemplar{}, "Timestamp"), cmpopts.IgnoreUnexported(metricdata.Exemplar{}))
 }
+
+func TestRecordWithMeter(t *testing.T) {
+	meter := view.NewMeter()
+	meter.Start()
+	defer meter.Stop()
+	k1 := tag.MustNewKey("k1")
+	k2 := tag.MustNewKey("k2")
+	m1 := stats.Int64("TestResolveOptions/m1", "", stats.UnitDimensionless)
+	m2 := stats.Int64("TestResolveOptions/m2", "", stats.UnitDimensionless)
+	v := []*view.View{{
+		Name:        "test_view",
+		TagKeys:     []tag.Key{k1, k2},
+		Measure:     m1,
+		Aggregation: view.Distribution(5, 10),
+	}, {
+		Name:        "second_view",
+		TagKeys:     []tag.Key{k1},
+		Measure:     m2,
+		Aggregation: view.Count(),
+	}}
+	meter.SetReportingPeriod(100 * time.Millisecond)
+	if err := meter.Register(v...); err != nil {
+		t.Fatalf("Failed to register view: %v", err)
+	}
+	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)
+	}
+	err = stats.RecordWithOptions(ctx,
+		stats.WithTags(tag.Upsert(k1, "bar"), tag.Insert(k2, "bar")),
+		stats.WithAttachments(attachments),
+		stats.WithMeasurements(m1.M(12), m1.M(6), m2.M(5)),
+		stats.WithRecorder(meter))
+	if err != nil {
+		t.Fatalf("Failed to resolve data point: %v", err)
+	}
+
+	rows, err := meter.RetrieveData("test_view")
+	if err != nil {
+		t.Fatalf("Unable to retrieve data for test_view: %v", err)
+	}
+	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)
+		}
+
+	}
+	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)
+		}
+	}
+
+	rows2, err := meter.RetrieveData("second_view")
+	if err != nil {
+		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)
+		}
+	}
+	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/benchmark_test.go

@@ -46,29 +46,15 @@ var (
 // BenchmarkRecordReqCommand benchmarks calling the internal recording machinery
 // directly.
 func BenchmarkRecordReqCommand(b *testing.B) {
-	w := newWorker()
+	w := NewMeter().(*worker)
 
 	register := &registerViewReq{views: []*View{view}, err: make(chan error, 1)}
 	register.handleCommand(w)
 	if err := <-register.err; err != nil {
 		b.Fatal(err)
 	}
 
-	const tagCount = 10
-	ctxs := make([]context.Context, 0, tagCount)
-	for i := 0; i < tagCount; i++ {
-		ctx, _ := tag.New(context.Background(),
-			tag.Upsert(k1, fmt.Sprintf("v%d", i)),
-			tag.Upsert(k2, fmt.Sprintf("v%d", i)),
-			tag.Upsert(k3, fmt.Sprintf("v%d", i)),
-			tag.Upsert(k4, fmt.Sprintf("v%d", i)),
-			tag.Upsert(k5, fmt.Sprintf("v%d", i)),
-			tag.Upsert(k6, fmt.Sprintf("v%d", i)),
-			tag.Upsert(k7, fmt.Sprintf("v%d", i)),
-			tag.Upsert(k8, fmt.Sprintf("v%d", i)),
-		)
-		ctxs = append(ctxs, ctx)
-	}
+	ctxs := prepareContexts(10)
 
 	b.ReportAllocs()
 	b.ResetTimer()
@@ -91,3 +77,41 @@ func BenchmarkRecordReqCommand(b *testing.B) {
 		record.handleCommand(w)
 	}
 }
+
+func BenchmarkRecordViaStats(b *testing.B) {
+
+	meter := NewMeter()
+	meter.Start()
+	defer meter.Stop()
+	meter.Register(view)
+	defer meter.Unregister(view)
+
+	ctxs := prepareContexts(10)
+	rec := stats.WithRecorder(meter)
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		stats.RecordWithOptions(ctxs[i%len(ctxs)], rec, stats.WithMeasurements(m.M(1), m.M(1), m.M(1), m.M(1), m.M(1), m.M(1), m.M(1), m.M(1)))
+	}
+
+}
+
+func prepareContexts(tagCount int) []context.Context {
+	ctxs := make([]context.Context, 0, tagCount)
+	for i := 0; i < tagCount; i++ {
+		ctx, _ := tag.New(context.Background(),
+			tag.Upsert(k1, fmt.Sprintf("v%d", i)),
+			tag.Upsert(k2, fmt.Sprintf("v%d", i)),
+			tag.Upsert(k3, fmt.Sprintf("v%d", i)),
+			tag.Upsert(k4, fmt.Sprintf("v%d", i)),
+			tag.Upsert(k5, fmt.Sprintf("v%d", i)),
+			tag.Upsert(k6, fmt.Sprintf("v%d", i)),
+			tag.Upsert(k7, fmt.Sprintf("v%d", i)),
+			tag.Upsert(k8, fmt.Sprintf("v%d", i)),
+		)
+		ctxs = append(ctxs, ctx)
+	}
+
+	return ctxs
+}

stats/view/export.go

@@ -14,13 +14,6 @@
 
 package view
 
-import "sync"
-
-var (
-	exportersMu sync.RWMutex // guards exporters
-	exporters   = make(map[Exporter]struct{})
-)
-
 // Exporter exports the collected records as view data.
 //
 // The ExportView method should return quickly; if an
@@ -43,16 +36,10 @@ type Exporter interface {
 //
 // Binaries can register exporters, libraries shouldn't register exporters.
 func RegisterExporter(e Exporter) {
-	exportersMu.Lock()
-	defer exportersMu.Unlock()
-
-	exporters[e] = struct{}{}
+	defaultWorker.RegisterExporter(e)
 }
 
 // UnregisterExporter unregisters an exporter.
 func UnregisterExporter(e Exporter) {
-	exportersMu.Lock()
-	defer exportersMu.Unlock()
-
-	delete(exporters, e)
+	defaultWorker.UnregisterExporter(e)
 }