Resolve "Add an option to send gNMI Subscribe requests via SBI"

Description

#227 (closed)

controller/nucleus/gnmi_transport.go

@@ -3,6 +3,8 @@ package nucleus
 import (
 	"context"
 	"fmt"
+	"path"
+	"time"
 
 	"code.fbi.h-da.de/danet/gosdn/controller/interfaces/change"
 
@@ -327,6 +329,70 @@ func (g *Gnmi) subscribe(ctx context.Context) error {
 	return gnmi.SubscribeErr(ctx, g.client, opts, g.RespChan)
 }
 
+// Subscribe calls GNMI subscribe
+func (g *Gnmi) subscribe2(ctx context.Context, stringRespChan chan string) error {
+	ctx = gnmi.NewContext(ctx, g.config)
+	opts, ok := ctx.Value(types.CtxKeyOpts).(*gnmi.SubscribeOptions)
+	if !ok {
+		return &errors.ErrInvalidTypeAssertion{
+			Value: ctx.Value(types.CtxKeyOpts),
+			Type:  &gnmi.SubscribeOptions{},
+		}
+	}
+	go func() {
+		log.WithFields(log.Fields{
+			"address":  opts.Target,
+			"paths":    opts.Paths,
+			"mode":     opts.Mode,
+			"interval": opts.SampleInterval,
+		}).Info("subscribed to gNMI target")
+		for {
+			resp := <-g.RespChan
+			if resp != nil {
+				if err := LogSubscribeResponse(resp, stringRespChan); err != nil {
+					log.Fatal(err)
+				}
+			}
+		}
+	}()
+	return gnmi.SubscribeErr(ctx, g.client, opts, g.RespChan)
+}
+
+// LogSubscribeResponse logs update responses to stderr.
+func LogSubscribeResponse(response *gpb.SubscribeResponse, stringRespChan chan string) error {
+	switch resp := response.Response.(type) {
+	case *gpb.SubscribeResponse_Error:
+		//return errors.New(resp.Error.Message)
+		//TODO: fix error
+		return errors.ErrNotYetImplemented{}
+	case *gpb.SubscribeResponse_SyncResponse:
+		if !resp.SyncResponse {
+			//return errors.New("initial sync failed")
+			//TODO: fix error
+			return errors.ErrNotYetImplemented{}
+		}
+	case *gpb.SubscribeResponse_Update:
+		t := time.Unix(0, resp.Update.Timestamp).UTC()
+		prefix := resp.Update.Prefix
+		var target string
+		if t := resp.Update.Prefix.GetTarget(); t != "" {
+			target = "(" + t + ") "
+		}
+		for _, update := range resp.Update.Update {
+			stringRespChan <- fmt.Sprintf("[%s] %s%s = %s\n", t.Format(time.RFC3339Nano),
+				target,
+				path.Join(prefix.String(), update.Path.String()),
+				update.String())
+		}
+		for _, del := range resp.Update.Delete {
+			stringRespChan <- fmt.Sprintf("[%s] %sDeleted %s\n", t.Format(time.RFC3339Nano),
+				target,
+				path.Join(prefix.String(), del.String()))
+		}
+	}
+	return nil
+}
+
 // Close calls GNMI close
 func (g *Gnmi) Close() error {
 	return nil