1 files changed, 172 insertions, 0 deletions
diff --git a/src/go/collectors/go.d.plugin/pkg/stm/stm.go b/src/go/collectors/go.d.plugin/pkg/stm/stm.go
new file mode 100644
index 000000000..7d07ba9a4
--- /dev/null
+++ b/src/go/collectors/go.d.plugin/pkg/stm/stm.go
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package stm
+
+import (
+	"fmt"
+	"log"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+const (
+	fieldTagName = "stm"
+	structKey    = "STMKey"
+)
+
+type (
+	Value interface {
+		WriteTo(rv map[string]int64, key string, mul, div int)
+	}
+)
+
+// ToMap converts struct to a map[string]int64 based on 'stm' tags
+func ToMap(s ...interface{}) map[string]int64 {
+	rv := map[string]int64{}
+	for _, v := range s {
+		value := reflect.Indirect(reflect.ValueOf(v))
+		toMap(value, rv, "", 1, 1)
+	}
+	return rv
+}
+
+func toMap(value reflect.Value, rv map[string]int64, key string, mul, div int) {
+	if !value.IsValid() {
+		log.Panicf("value is not valid key=%s", key)
+	}
+	if value.CanInterface() {
+		val, ok := value.Interface().(Value)
+		if ok {
+			val.WriteTo(rv, key, mul, div)
+			return
+		}
+	}
+	switch value.Kind() {
+	case reflect.Ptr:
+		convertPtr(value, rv, key, mul, div)
+	case reflect.Struct:
+		convertStruct(value, rv, key)
+	case reflect.Array, reflect.Slice:
+		convertArraySlice(value, rv, key, mul, div)
+	case reflect.Map:
+		convertMap(value, rv, key, mul, div)
+	case reflect.Bool:
+		convertBool(value, rv, key)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		convertInteger(value, rv, key, mul, div)
+	case reflect.Float32, reflect.Float64:
+		convertFloat(value, rv, key, mul, div)
+	case reflect.Interface:
+		convertInterface(value, rv, key, mul, div)
+	default:
+		log.Panicf("unsupported data type: %v", value.Kind())
+	}
+}
+
+func convertPtr(value reflect.Value, rv map[string]int64, key string, mul, div int) {
+	if !value.IsNil() {
+		toMap(value.Elem(), rv, key, mul, div)
+	}
+}
+
+func convertStruct(value reflect.Value, rv map[string]int64, key string) {
+	t := value.Type()
+	k := value.FieldByName(structKey)
+	if k.Kind() == reflect.String {
+		key = joinPrefix(key, k.String())
+	}
+	for i := 0; i < t.NumField(); i++ {
+		ft := t.Field(i)
+		tag, ok := ft.Tag.Lookup(fieldTagName)
+		if !ok || ft.Name == structKey {
+			continue
+		}
+		value := value.Field(i)
+		prefix, mul, div := parseTag(tag)
+		toMap(value, rv, joinPrefix(key, prefix), mul, div)
+	}
+}
+
+func convertMap(value reflect.Value, rv map[string]int64, key string, mul, div int) {
+	if value.IsNil() {
+		log.Panicf("value is nil key=%s", key)
+	}
+	for _, k := range value.MapKeys() {
+		toMap(value.MapIndex(k), rv, joinPrefix(key, k.String()), mul, div)
+	}
+}
+
+func convertArraySlice(value reflect.Value, rv map[string]int64, key string, mul, div int) {
+	for i := 0; i < value.Len(); i++ {
+		toMap(value.Index(i), rv, key, mul, div)
+	}
+}
+
+func convertBool(value reflect.Value, rv map[string]int64, key string) {
+	if _, ok := rv[key]; ok {
+		log.Panic("duplicate key: ", key)
+	}
+	if value.Bool() {
+		rv[key] = 1
+	} else {
+		rv[key] = 0
+	}
+}
+
+func convertInteger(value reflect.Value, rv map[string]int64, key string, mul, div int) {
+	if _, ok := rv[key]; ok {
+		log.Panic("duplicate key: ", key)
+	}
+	intVal := value.Int()
+	rv[key] = intVal * int64(mul) / int64(div)
+}
+
+func convertFloat(value reflect.Value, rv map[string]int64, key string, mul, div int) {
+	if _, ok := rv[key]; ok {
+		log.Panic("duplicate key: ", key)
+	}
+	floatVal := value.Float()
+	rv[key] = int64(floatVal * float64(mul) / float64(div))
+}
+
+func convertInterface(value reflect.Value, rv map[string]int64, key string, mul, div int) {
+	fv := reflect.ValueOf(value.Interface())
+	toMap(fv, rv, key, mul, div)
+}
+
+func joinPrefix(prefix, key string) string {
+	if prefix == "" {
+		return key
+	}
+	if key == "" {
+		return prefix
+	}
+	return prefix + "_" + key
+}
+
+func parseTag(tag string) (prefix string, mul int, div int) {
+	tokens := strings.Split(tag, ",")
+	mul = 1
+	div = 1
+	var err error
+	switch len(tokens) {
+	case 3:
+		div, err = strconv.Atoi(tokens[2])
+		if err != nil {
+			log.Panic(err)
+		}
+		fallthrough
+	case 2:
+		mul, err = strconv.Atoi(tokens[1])
+		if err != nil {
+			log.Panic(err)
+		}
+		fallthrough
+	case 1:
+		prefix = tokens[0]
+	default:
+		log.Panic(fmt.Errorf("invalid tag format: %s", tag))
+	}
+	return
+}