feat: don't use go maps package (for v1.20.x compatibility)

internal/digest/aggregate.go

@@ -7,6 +7,16 @@ import (
 // Aggregate contains aggregated values by aggregation name.
 type Aggregate map[string]float64
 
+func (agg Aggregate) clone() Aggregate {
+	other := make(Aggregate, len(agg))
+
+	for key, value := range agg {
+		other[key] = value
+	}
+
+	return other
+}
+
 // Aggregates contains aggregetes by metric name.
 type Aggregates map[string]Aggregate
 
@@ -24,3 +34,13 @@ func (a Aggregates) Time() time.Time {
 
 	return time.UnixMilli(int64(val))
 }
+
+func (a Aggregates) clone() Aggregates {
+	other := make(Aggregates, len(a))
+
+	for key, value := range a {
+		other[key] = value.clone()
+	}
+
+	return other
+}

internal/digest/digest.go

@@ -2,7 +2,6 @@
 package digest
 
 import (
-	"maps"
 	"time"
 )
 
@@ -33,9 +32,9 @@ func newDigest(from *Digest) *Digest {
 		d.Start = from.Start
 		d.Stop = from.Stop
 		d.Param = from.Param
-		d.Cumulative = maps.Clone(from.Cumulative)
-		d.Snapshot = maps.Clone(from.Snapshot)
-		d.Metrics = maps.Clone(from.Metrics)
+		d.Cumulative = from.Cumulative.clone()
+		d.Snapshot = from.Snapshot.clone()
+		d.Metrics = from.Metrics.clone()
 		d.State = from.State
 		if d.Config == nil {
 			d.Config = make(map[string]interface{})

internal/digest/metrics.go

@@ -16,3 +16,13 @@ func (mets Metrics) Find(name string) (*Metric, bool) {
 
 	return met, found
 }
+
+func (mets Metrics) clone() Metrics {
+	other := make(Metrics, len(mets))
+
+	for key, value := range mets {
+		other[key] = value
+	}
+
+	return other
+}