use a list for all valid agg types

policy/unaggregated/aggregation_type.go

@@ -57,35 +57,36 @@ const (
 
 var (
 	emptyStruct struct{}
-	// EmptyAggregationTypes is an empty list of AggregationTypes.
+	// EmptyAggregationTypes is an empty list of aggregation types.
 	EmptyAggregationTypes AggregationTypes
 
 	// EmptyAggregationID is an empty AggregationID.
 	EmptyAggregationID AggregationID
 
-	validAggregationTypesMap = map[AggregationType]struct{}{
-		Last:   emptyStruct,
-		Lower:  emptyStruct,
-		Upper:  emptyStruct,
-		Mean:   emptyStruct,
-		Median: emptyStruct,
-		Count:  emptyStruct,
-		Sum:    emptyStruct,
-		SumSq:  emptyStruct,
-		Stdev:  emptyStruct,
-		P50:    emptyStruct,
-		P95:    emptyStruct,
-		P99:    emptyStruct,
-		P999:   emptyStruct,
-		P9999:  emptyStruct,
+	// ValidAggregationTypes is the list of valid aggregation types
+	ValidAggregationTypes = []AggregationType{
+		Last,
+		Lower,
+		Upper,
+		Mean,
+		Median,
+		Count,
+		Sum,
+		SumSq,
+		Stdev,
+		P50,
+		P95,
+		P99,
+		P999,
+		P9999,
 	}
 
 	aggregationTypeStringMap map[string]AggregationType
 )
 
 func init() {
 	aggregationTypeStringMap = make(map[string]AggregationType, totalAggregationTypes)
-	for aggType := range validAggregationTypesMap {
+	for _, aggType := range ValidAggregationTypes {
 		aggregationTypeStringMap[aggType.String()] = aggType
 	}
 }