add zero bucket if not present. (#89)

* add zero bucket if not present.

* rename functions.

equivalence_test.go

@@ -182,7 +182,7 @@ func TestEquivalenceStatsVsMetricsUploads(t *testing.T) {
 				View: &view.View{
 					Name:        "ocagent.io/latency",
 					Description: "The latency of the various methods",
-					Aggregation: view.Distribution(0, 100, 500, 1000, 2000, 4000, 8000, 16000),
+					Aggregation: view.Distribution(100, 500, 1000, 2000, 4000, 8000, 16000),
 					Measure:     mLatencyMs,
 				},
 				Rows: []*view.Row{
@@ -192,9 +192,9 @@ func TestEquivalenceStatsVsMetricsUploads(t *testing.T) {
 							Min:            100,
 							Max:            500,
 							Mean:           125.9,
-							CountPerBucket: []int64{0, 0, 1, 0, 0, 0, 0, 0},
+							CountPerBucket: []int64{0, 1, 0, 0, 0, 0, 0},
 							ExemplarsPerBucket: []*exemplar.Exemplar{
-								nil, nil,
+								nil,
 								{
 									Value: 125.9, Timestamp: startTime.Add(time.Duration(1+i) * time.Second),
 								},

metrics.go

@@ -461,22 +461,28 @@ func protoToMetricPoint(value interface{}) (*monitoringpb.TypedValue, error) {
 					Count:                 dv.Count,
 					Mean:                  mean,
 					SumOfSquaredDeviation: dv.SumOfSquaredDeviation,
-					BucketCounts:          bucketCounts(dv.Buckets),
 				},
 			}
 
+			insertZeroBound := false
 			if bopts := dv.BucketOptions; bopts != nil && bopts.Type != nil {
 				bexp, ok := bopts.Type.(*metricspb.DistributionValue_BucketOptions_Explicit_)
 				if ok && bexp != nil && bexp.Explicit != nil {
+					insertZeroBound = shouldInsertZeroBound(bexp.Explicit.Bounds...)
 					mv.DistributionValue.BucketOptions = &distributionpb.Distribution_BucketOptions{
 						Options: &distributionpb.Distribution_BucketOptions_ExplicitBuckets{
 							ExplicitBuckets: &distributionpb.Distribution_BucketOptions_Explicit{
-								Bounds: bexp.Explicit.Bounds[:],
+								// The first bucket bound should be 0.0 because the Metrics first bucket is
+								// [0, first_bound) but Stackdriver monitoring bucket bounds begin with -infinity
+								// (first bucket is (-infinity, 0))
+								Bounds: addZeroBoundOnCondition(insertZeroBound, bexp.Explicit.Bounds...),
 							},
 						},
 					}
 				}
 			}
+			mv.DistributionValue.BucketCounts = addZeroBucketCountOnCondition(insertZeroBound, bucketCounts(dv.Buckets)...)
+
 		}
 		tval = &monitoringpb.TypedValue{Value: mv}
 	}

metrics_test.go

@@ -117,12 +117,13 @@ func TestProtoMetricToCreateTimeSeriesRequest(t *testing.T) {
 										Sum:                   11.9,
 										SumOfSquaredDeviation: 0,
 										Buckets: []*metricspb.DistributionValue_Bucket{
-											{}, {Count: 1}, {}, {}, {},
+											{Count: 1}, {}, {}, {},
 										},
 										BucketOptions: &metricspb.DistributionValue_BucketOptions{
 											Type: &metricspb.DistributionValue_BucketOptions_Explicit_{
 												Explicit: &metricspb.DistributionValue_BucketOptions_Explicit{
-													Bounds: []float64{0, 10, 20, 30, 40},
+													// Without zero bucket in
+													Bounds: []float64{10, 20, 30, 40},
 												},
 											},
 										},
@@ -322,6 +323,7 @@ func TestProtoMetricsToMonitoringMetrics_fromProtoPoint(t *testing.T) {
 						BucketOptions: &metricspb.DistributionValue_BucketOptions{
 							Type: &metricspb.DistributionValue_BucketOptions_Explicit_{
 								Explicit: &metricspb.DistributionValue_BucketOptions_Explicit{
+									// With zero bucket in
 									Bounds: []float64{0, 10, 20, 30, 40},
 								},
 							},

stats.go

@@ -423,6 +423,7 @@ func newTypedValue(vd *view.View, r *view.Row) *monitoringpb.TypedValue {
 			}}
 		}
 	case *view.DistributionData:
+		insertZeroBound := shouldInsertZeroBound(vd.Aggregation.Buckets...)
 		return &monitoringpb.TypedValue{Value: &monitoringpb.TypedValue_DistributionValue{
 			DistributionValue: &distributionpb.Distribution{
 				Count:                 v.Count,
@@ -436,11 +437,11 @@ func newTypedValue(vd *view.View, r *view.Row) *monitoringpb.TypedValue {
 				BucketOptions: &distributionpb.Distribution_BucketOptions{
 					Options: &distributionpb.Distribution_BucketOptions_ExplicitBuckets{
 						ExplicitBuckets: &distributionpb.Distribution_BucketOptions_Explicit{
-							Bounds: vd.Aggregation.Buckets,
+							Bounds: addZeroBoundOnCondition(insertZeroBound, vd.Aggregation.Buckets...),
 						},
 					},
 				},
-				BucketCounts: v.CountPerBucket,
+				BucketCounts: addZeroBucketCountOnCondition(insertZeroBound, v.CountPerBucket...),
 			},
 		}}
 	case *view.LastValueData:
@@ -458,6 +459,27 @@ func newTypedValue(vd *view.View, r *view.Row) *monitoringpb.TypedValue {
 	return nil
 }
 
+func shouldInsertZeroBound(bounds ...float64) bool {
+	if len(bounds) > 0 && bounds[0] != 0.0 {
+		return true
+	}
+	return false
+}
+
+func addZeroBucketCountOnCondition(insert bool, counts ...int64) []int64 {
+	if insert {
+		return append([]int64{0}, counts...)
+	}
+	return counts
+}
+
+func addZeroBoundOnCondition(insert bool, bounds ...float64) []float64 {
+	if insert {
+		return append([]float64{0.0}, bounds...)
+	}
+	return bounds
+}
+
 func (e *statsExporter) metricType(v *view.View) string {
 	if formatter := e.o.GetMetricType; formatter != nil {
 		return formatter(v)

stats_test.go

@@ -399,7 +399,7 @@ func TestExporter_makeReq(t *testing.T) {
 			},
 		},
 		{
-			name:   "dist agg + time window",
+			name:   "dist agg + time window - without zero bucket",
 			projID: "proj-id",
 			vd:     newTestDistViewData(distView, start, end),
 			want: []*monitoringpb.CreateTimeSeriesRequest{{
@@ -435,8 +435,54 @@ func TestExporter_makeReq(t *testing.T) {
 										BucketOptions: &distribution.Distribution_BucketOptions{
 											Options: &distribution.Distribution_BucketOptions_ExplicitBuckets{
 												ExplicitBuckets: &distribution.Distribution_BucketOptions_Explicit{
-													Bounds: []float64{2.0, 4.0, 7.0}}}},
-										BucketCounts: []int64{2, 2, 1}},
+													Bounds: []float64{0.0, 2.0, 4.0, 7.0}}}},
+										BucketCounts: []int64{0, 2, 2, 1}},
+								}},
+							},
+						},
+					},
+				},
+			}},
+		},
+		{
+			name:   "dist agg + time window + zero bucket",
+			projID: "proj-id",
+			vd:     newTestDistViewData(distView, start, end),
+			want: []*monitoringpb.CreateTimeSeriesRequest{{
+				Name: monitoring.MetricProjectPath("proj-id"),
+				TimeSeries: []*monitoringpb.TimeSeries{
+					{
+						Metric: &metricpb.Metric{
+							Type: "custom.googleapis.com/opencensus/distview",
+							Labels: map[string]string{
+								opencensusTaskKey: taskValue,
+							},
+						},
+						Resource: &monitoredrespb.MonitoredResource{
+							Type: "global",
+						},
+						Points: []*monitoringpb.Point{
+							{
+								Interval: &monitoringpb.TimeInterval{
+									StartTime: &timestamp.Timestamp{
+										Seconds: start.Unix(),
+										Nanos:   int32(start.Nanosecond()),
+									},
+									EndTime: &timestamp.Timestamp{
+										Seconds: end.Unix(),
+										Nanos:   int32(end.Nanosecond()),
+									},
+								},
+								Value: &monitoringpb.TypedValue{Value: &monitoringpb.TypedValue_DistributionValue{
+									DistributionValue: &distribution.Distribution{
+										Count:                 5,
+										Mean:                  3.0,
+										SumOfSquaredDeviation: 1.5,
+										BucketOptions: &distribution.Distribution_BucketOptions{
+											Options: &distribution.Distribution_BucketOptions_ExplicitBuckets{
+												ExplicitBuckets: &distribution.Distribution_BucketOptions_Explicit{
+													Bounds: []float64{0.0, 2.0, 4.0, 7.0}}}},
+										BucketCounts: []int64{0, 2, 2, 1}},
 								}},
 							},
 						},
@@ -1411,3 +1457,21 @@ func newTestDistViewData(v *view.View, start, end time.Time) *view.Data {
 		End:   end,
 	}
 }
+
+func newTestDistViewDataWithZeroBucket(v *view.View, start, end time.Time) *view.Data {
+	return &view.Data{
+		View: v,
+		Rows: []*view.Row{
+			{Data: &view.DistributionData{
+				Count:           5,
+				Min:             1,
+				Max:             7,
+				Mean:            3,
+				SumOfSquaredDev: 1.5,
+				CountPerBucket:  []int64{0, 2, 2, 1},
+			}},
+		},
+		Start: start,
+		End:   end,
+	}
+}