Expose the id of aggregation types

policy/aggregation_type.go

@@ -62,6 +62,9 @@ const (
 	// The AggregationIDLen will be 1 when totalAggregationTypes <= 64.
 	AggregationIDLen = (totalAggregationTypes-1)/64 + 1
 
+	// MaxAggregationTypeID is the largest id of all the valid aggregation types.
+	MaxAggregationTypeID = totalAggregationTypes - 1
+
 	aggregationTypesSeparator = ","
 )
 
@@ -122,6 +125,11 @@ func NewAggregationTypeFromSchema(input schema.AggregationType) (AggregationType
 	return aggType, nil
 }
 
+// ID returns the id of the AggregationType.
+func (a AggregationType) ID() int {
+	return int(a)
+}
+
 // IsValid checks if an AggregationType is valid.
 func (a AggregationType) IsValid() bool {
 	_, ok := ValidAggregationTypes[a]

policy/aggregation_type_test.go

@@ -34,6 +34,11 @@ func TestAggregationTypeIsValid(t *testing.T) {
 	require.False(t, AggregationType(int(P9999)+1).IsValid())
 }
 
+func TestAggregationTypeID(t *testing.T) {
+	require.Equal(t, MaxAggregationTypeID, P9999.ID())
+	require.Equal(t, P9999, AggregationType(MaxAggregationTypeID))
+}
+
 func TestAggregationTypesIsDefault(t *testing.T) {
 	require.True(t, DefaultAggregationTypes.IsDefault())