Report breakdown timings in microseconds

breakdown.go

@@ -40,10 +40,10 @@ const (
 
 	// Breakdown metric names.
 	transactionDurationCountMetricName  = "transaction.duration.count"
-	transactionDurationSumMetricName    = "transaction.duration.sum"
+	transactionDurationSumMetricName    = "transaction.duration.sum.us"
 	transactionBreakdownCountMetricName = "transaction.breakdown.count"
 	spanSelfTimeCountMetricName         = "span.self_time.count"
-	spanSelfTimeSumMetricName           = "span.self_time.sum"
+	spanSelfTimeSumMetricName           = "span.self_time.sum.us"
 
 	transactionBreakdownMetricFlag breakdownMetricsFlags = 1 << iota
 )
@@ -281,7 +281,7 @@ func (m *breakdownMetrics) gather(out *Metrics) {
 							Value: float64(entry.transaction.count),
 						},
 						transactionDurationSumMetricName: {
-							Value: durationMillis(time.Duration(entry.transaction.duration)),
+							Value: durationMicros(time.Duration(entry.transaction.duration)),
 						},
 						transactionBreakdownCountMetricName: {
 							Value: float64(entry.breakdownCount),
@@ -300,7 +300,7 @@ func (m *breakdownMetrics) gather(out *Metrics) {
 							Value: float64(entry.span.count),
 						},
 						spanSelfTimeSumMetricName: {
-							Value: durationMillis(time.Duration(entry.span.duration)),
+							Value: durationMicros(time.Duration(entry.span.duration)),
 						},
 					},
 				})

breakdown_test.go

@@ -33,9 +33,6 @@ import (
 	"go.elastic.co/apm/transport/transporttest"
 )
 
-// TODO(axw) check duration units. Doc says micros, we're currently dealing in millis.
-// TODO(axw) check if we need to report metric sets without sample values, as in the doc
-
 func TestBreakdownMetrics_NonSampled(t *testing.T) {
 	tracer, transport := transporttest.NewRecorderTracer()
 	defer tracer.Close()
@@ -494,7 +491,7 @@ func transactionDurationMetrics(txName, txType string, count int, sum time.Durat
 		Samples: map[string]model.Metric{
 			"transaction.breakdown.count": {Value: float64(count)},
 			"transaction.duration.count":  {Value: float64(count)},
-			"transaction.duration.sum":    {Value: sum.Seconds() * 1000},
+			"transaction.duration.sum.us": {Value: sum.Seconds() * 1000000},
 		},
 	}
 }
@@ -506,8 +503,8 @@ func spanSelfTimeMetrics(txName, txType, spanType, spanSubtype string, count int
 		SpanType:        spanType,
 		SpanSubtype:     spanSubtype,
 		Samples: map[string]model.Metric{
-			"span.self_time.count": {Value: float64(count)},
-			"span.self_time.sum":   {Value: sum.Seconds() * 1000},
+			"span.self_time.count":  {Value: float64(count)},
+			"span.self_time.sum.us": {Value: sum.Seconds() * 1000000},
 		},
 	}
 }

utils.go

@@ -192,8 +192,8 @@ func jitterDuration(d time.Duration, rng *rand.Rand, j float64) time.Duration {
 	return d + time.Duration(float64(d)*r)
 }
 
-func durationMillis(d time.Duration) float64 {
-	ms := d / time.Millisecond
-	ns := d % time.Millisecond
-	return float64(ms) + float64(ns)/1e6
+func durationMicros(d time.Duration) float64 {
+	us := d / time.Microsecond
+	ns := d % time.Microsecond
+	return float64(us) + float64(ns)/1e9
 }