Support logging more Go types to ETW

Signed-off-by: Kevin Parsons <kevpar@ntdev.microsoft.com>

pkg/etwlogrus/hook.go

@@ -53,12 +53,7 @@ func (h *Hook) Fire(e *logrus.Entry) error {
 	fields = append(fields, etw.StringField("Message", e.Message))
 
 	for k, v := range e.Data {
-		switch v := v.(type) {
-		case string:
-			fields = append(fields, etw.StringField(k, v))
-		default:
-			fields = append(fields, etw.StringField(k, fmt.Sprintf("<unknown type: %v> %v", reflect.TypeOf(v), v)))
-		}
+		fields = append(fields, getFieldOpt(k, v))
 	}
 
 	// We could try to map Logrus levels to ETW levels, but we would lose some
@@ -70,6 +65,127 @@ func (h *Hook) Fire(e *logrus.Entry) error {
 		fields)
 }
 
+// Currently, we support logging basic builtin types (int, string, etc), slices
+// of basic builtin types, error, types derived from the basic types (e.g. "type
+// foo int"), and structs (recursively logging their fields). We do not support
+// slices of derived types (e.g. "[]foo").
+//
+// For types that we don't support, the value is formatted via fmt.Sprint, and
+// we also log a message that the type is unsupported along with the formatted
+// type. The intent of this is to make it easier to see which types are not
+// supported in traces, so we can evaluate adding support for more types in the
+// future.
+func getFieldOpt(k string, v interface{}) etw.FieldOpt {
+	switch v := v.(type) {
+	case bool:
+		return etw.BoolField(k, v)
+	case []bool:
+		return etw.BoolArray(k, v)
+	case string:
+		return etw.StringField(k, v)
+	case []string:
+		return etw.StringArray(k, v)
+	case int:
+		return etw.IntField(k, v)
+	case []int:
+		return etw.IntArray(k, v)
+	case int8:
+		return etw.Int8Field(k, v)
+	case []int8:
+		return etw.Int8Array(k, v)
+	case int16:
+		return etw.Int16Field(k, v)
+	case []int16:
+		return etw.Int16Array(k, v)
+	case int32:
+		return etw.Int32Field(k, v)
+	case []int32:
+		return etw.Int32Array(k, v)
+	case int64:
+		return etw.Int64Field(k, v)
+	case []int64:
+		return etw.Int64Array(k, v)
+	case uint:
+		return etw.UintField(k, v)
+	case []uint:
+		return etw.UintArray(k, v)
+	case uint8:
+		return etw.Uint8Field(k, v)
+	case []uint8:
+		return etw.Uint8Array(k, v)
+	case uint16:
+		return etw.Uint16Field(k, v)
+	case []uint16:
+		return etw.Uint16Array(k, v)
+	case uint32:
+		return etw.Uint32Field(k, v)
+	case []uint32:
+		return etw.Uint32Array(k, v)
+	case uint64:
+		return etw.Uint64Field(k, v)
+	case []uint64:
+		return etw.Uint64Array(k, v)
+	case uintptr:
+		return etw.UintptrField(k, v)
+	case []uintptr:
+		return etw.UintptrArray(k, v)
+	case float32:
+		return etw.Float32Field(k, v)
+	case []float32:
+		return etw.Float32Array(k, v)
+	case float64:
+		return etw.Float64Field(k, v)
+	case []float64:
+		return etw.Float64Array(k, v)
+	case error:
+		return etw.StringField(k, v.Error())
+	default:
+		switch rv := reflect.ValueOf(v); rv.Kind() {
+		case reflect.Bool:
+			return getFieldOpt(k, rv.Bool())
+		case reflect.Int:
+			return getFieldOpt(k, int(rv.Int()))
+		case reflect.Int8:
+			return getFieldOpt(k, int8(rv.Int()))
+		case reflect.Int16:
+			return getFieldOpt(k, int16(rv.Int()))
+		case reflect.Int32:
+			return getFieldOpt(k, int32(rv.Int()))
+		case reflect.Int64:
+			return getFieldOpt(k, int64(rv.Int()))
+		case reflect.Uint:
+			return getFieldOpt(k, uint(rv.Uint()))
+		case reflect.Uint8:
+			return getFieldOpt(k, uint8(rv.Uint()))
+		case reflect.Uint16:
+			return getFieldOpt(k, uint16(rv.Uint()))
+		case reflect.Uint32:
+			return getFieldOpt(k, uint32(rv.Uint()))
+		case reflect.Uint64:
+			return getFieldOpt(k, uint64(rv.Uint()))
+		case reflect.Uintptr:
+			return getFieldOpt(k, uintptr(rv.Uint()))
+		case reflect.Float32:
+			return getFieldOpt(k, float32(rv.Float()))
+		case reflect.Float64:
+			return getFieldOpt(k, float64(rv.Float()))
+		case reflect.String:
+			return getFieldOpt(k, rv.String())
+		case reflect.Struct:
+			fields := make([]etw.FieldOpt, 0, rv.NumField())
+			for i := 0; i < rv.NumField(); i++ {
+				field := rv.Field(i)
+				if field.CanInterface() {
+					fields = append(fields, getFieldOpt(k, field.Interface()))
+				}
+			}
+			return etw.Struct(k, fields...)
+		}
+	}
+
+	return etw.StringField(k, fmt.Sprintf("(Unsupported: %T) %v", v, v))
+}
+
 // Close cleans up the hook and closes the ETW provider.
 func (h *Hook) Close() error {
 	return h.provider.Close()