fix: stabilize federated agent runtime updates (#550)

go-gost/x/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"encoding/json"
 	"io"
+	"reflect"
 	"sync"
 	"time"
 
@@ -30,9 +31,87 @@ func Global() *Config {
 	globalMux.RLock()
 	defer globalMux.RUnlock()
 
-	cfg := &Config{}
-	*cfg = *global
-	return cfg
+	return cloneConfig(global)
+}
+
+// cloneConfig returns a detached snapshot of the runtime config. Runtime
+// commands mutate slices, pointers and metadata maps, so a shallow struct copy
+// is not sufficient once readers and persistence run concurrently.
+func cloneConfig(c *Config) *Config {
+	if c == nil {
+		return nil
+	}
+	v := cloneConfigValue(reflect.ValueOf(c))
+	if !v.IsValid() || v.IsNil() {
+		return nil
+	}
+	return v.Interface().(*Config)
+}
+
+func cloneConfigValue(v reflect.Value) reflect.Value {
+	if !v.IsValid() {
+		return reflect.Value{}
+	}
+
+	switch v.Kind() {
+	case reflect.Interface:
+		if v.IsNil() {
+			return reflect.Zero(v.Type())
+		}
+		cloned := cloneConfigValue(v.Elem())
+		out := reflect.New(v.Type()).Elem()
+		if cloned.IsValid() && cloned.Type().AssignableTo(v.Type()) {
+			out.Set(cloned)
+		} else if cloned.IsValid() && cloned.Type().Implements(v.Type()) {
+			out.Set(cloned)
+		} else if cloned.IsValid() {
+			out.Set(cloned)
+		}
+		return out
+	case reflect.Pointer:
+		if v.IsNil() {
+			return reflect.Zero(v.Type())
+		}
+		out := reflect.New(v.Type().Elem())
+		out.Elem().Set(cloneConfigValue(v.Elem()))
+		return out
+	case reflect.Map:
+		if v.IsNil() {
+			return reflect.Zero(v.Type())
+		}
+		out := reflect.MakeMapWithSize(v.Type(), v.Len())
+		iter := v.MapRange()
+		for iter.Next() {
+			out.SetMapIndex(cloneConfigValue(iter.Key()), cloneConfigValue(iter.Value()))
+		}
+		return out
+	case reflect.Slice:
+		if v.IsNil() {
+			return reflect.Zero(v.Type())
+		}
+		out := reflect.MakeSlice(v.Type(), v.Len(), v.Len())
+		for i := 0; i < v.Len(); i++ {
+			out.Index(i).Set(cloneConfigValue(v.Index(i)))
+		}
+		return out
+	case reflect.Array:
+		out := reflect.New(v.Type()).Elem()
+		for i := 0; i < v.Len(); i++ {
+			out.Index(i).Set(cloneConfigValue(v.Index(i)))
+		}
+		return out
+	case reflect.Struct:
+		out := reflect.New(v.Type()).Elem()
+		out.Set(v)
+		for i := 0; i < v.NumField(); i++ {
+			if out.Field(i).CanSet() && v.Field(i).CanInterface() {
+				out.Field(i).Set(cloneConfigValue(v.Field(i)))
+			}
+		}
+		return out
+	default:
+		return v
+	}
 }
 
 func Set(c *Config) {