remove selectCase and remove any signs of 2 defaults

Signed-off-by: alecholmez <alecholmez@me.com>

oops remove that

Signed-off-by: alecholmez <alecholmez@me.com>

stash changes

Signed-off-by: alecholmez <alecholmez@me.com>

Author: alecholmez

pkg/server/sotw/v3/server.go

@@ -85,10 +85,10 @@ func (s *server) process(str stream.Stream, reqCh <-chan *discovery.DiscoveryReq
 	lastDiscoveryResponses := map[string]lastDiscoveryResponse{}
 
 	// a collection of stack allocated watches per request type
-	watches := newWatches(reqCh)
+	watches := newWatches()
 
 	defer func() {
-		watches.Cancel()
+		watches.close()
 		if s.callbacks != nil {
 			s.callbacks.OnStreamClosed(streamID)
 		}
@@ -124,14 +124,6 @@ func (s *server) process(str stream.Stream, reqCh <-chan *discovery.DiscoveryReq
 		return out.Nonce, str.Send(out)
 	}
 
-	open := func(w *watch, req *discovery.DiscoveryRequest, responder chan cache.Response) {
-		w.cancel = s.cache.CreateWatch(req, streamState, responder)
-		watches.cases[w.index] = reflect.SelectCase{
-			Dir:  reflect.SelectRecv,
-			Chan: reflect.ValueOf(responder),
-		}
-	}
-
 	if s.callbacks != nil {
 		if err := s.callbacks.OnStreamOpen(str.Context(), streamID, defaultTypeURL); err != nil {
 			return err
@@ -142,7 +134,7 @@ func (s *server) process(str stream.Stream, reqCh <-chan *discovery.DiscoveryReq
 	var node = &core.Node{}
 
 	// recompute dynamic channels for this stream
-	watches.RecomputeWatches(s.ctx, reqCh)
+	watches.recompute(s.ctx, reqCh)
 
 	for {
 		// The list of select cases looks like this:
@@ -204,27 +196,36 @@ func (s *server) process(str stream.Stream, reqCh <-chan *discovery.DiscoveryReq
 				// We've found a pre-existing watch, lets check and update if needed.
 				// If these requirements aren't satisfied, leave an open watch.
 				if w.nonce == "" || w.nonce == nonce {
-					w.Cancel()
+					w.close()
 
-					open(w, req, responder)
+					watches.addWatch(typeURL, &watch{
+						cancel:   s.cache.CreateWatch(req, streamState, responder),
+						response: responder,
+					})
 				}
 			} else {
 				// No pre-existing watch exists, let's create one.
 				// We need to precompute the watches first then open a watch in the cache.
 				watches.responders[typeURL] = &watch{}
 				w = watches.responders[typeURL]
-				watches.RecomputeWatches(s.ctx, reqCh)
+				watches.recompute(s.ctx, reqCh)
 
-				open(w, req, responder)
+				watches.addWatch(typeURL, &watch{
+					cancel:   s.cache.CreateWatch(req, streamState, responder),
+					response: responder,
+				})
 			}
+
+			// Recompute the dynamic select cases for this stream.
+			watches.recompute(s.ctx, reqCh)
 		default:
 			// Channel n -> these are the dynamic list of responders that correspond to the stream request typeURL
 			if !ok {
-				return status.Errorf(codes.Unavailable, "resource watch failed")
+				return status.Errorf(codes.Unavailable, "resource watch %d -> failed", index)
 			}
 
 			res := value.Interface().(cache.Response)
-			nonce, err := send(value.Interface().(cache.Response))
+			nonce, err := send(res)
 			if err != nil {
 				return err
 			}

pkg/server/sotw/v3/watches.go

@@ -6,6 +6,7 @@ import (
 
 	discovery "github.com/envoyproxy/go-control-plane/envoy/service/discovery/v3"
 	"github.com/envoyproxy/go-control-plane/pkg/cache/types"
+	"github.com/envoyproxy/go-control-plane/pkg/cache/v3"
 )
 
 // watches for all xDS resource types
@@ -17,57 +18,56 @@ type watches struct {
 }
 
 // newWatches creates and initializes watches.
-func newWatches(req <-chan *discovery.DiscoveryRequest) watches {
+func newWatches() watches {
 	return watches{
 		responders: make(map[string]*watch, int(types.UnknownType)),
-		cases:      make([]reflect.SelectCase, 2), // We use 2 for the default computation here: ctx.Done() + reqCh.Recv()
+		cases:      make([]reflect.SelectCase, 0),
 	}
 }
 
-// Cancel all watches
-func (w *watches) Cancel() {
+// addWatch creates a new watch entry in the watches map.
+// Watches are sorted by typeURL.
+func (w *watches) addWatch(typeURL string, watch *watch) {
+	w.responders[typeURL] = watch
+}
+
+// close all open watches
+func (w *watches) close() {
 	for _, watch := range w.responders {
-		watch.Cancel()
+		watch.close()
 	}
 }
 
 // recomputeWatches rebuilds the known list of dynamic channels if needed
-func (w *watches) RecomputeWatches(ctx context.Context, reqCh <-chan *discovery.DiscoveryRequest) {
-	newCases := []reflect.SelectCase{
-		{
+func (w *watches) recompute(ctx context.Context, req <-chan *discovery.DiscoveryRequest) {
+	w.cases = w.cases[0:]
+	w.cases = append(w.cases,
+		reflect.SelectCase{
 			Dir:  reflect.SelectRecv,
 			Chan: reflect.ValueOf(ctx.Done()),
-		},
-		{
+		}, reflect.SelectCase{
 			Dir:  reflect.SelectRecv,
-			Chan: reflect.ValueOf(reqCh),
+			Chan: reflect.ValueOf(req),
 		},
-	}
+	)
 
-	index := len(newCases)
 	for _, watch := range w.responders {
-		newCases = append(newCases, watch.selectCase)
-		watch.index = index
-		index++
+		w.cases = append(w.cases, reflect.SelectCase{
+			Dir:  reflect.SelectRecv,
+			Chan: reflect.ValueOf(watch.response),
+		})
 	}
-
-	w.cases = newCases
 }
 
 // watch contains the necessary modifiables for receiving resource responses
 type watch struct {
-	selectCase reflect.SelectCase
-	cancel     func()
-	nonce      string
-
-	// Index is used to track the location of this channel in watches. This allows us
-	// to update the channel used at this slot without recomputing the entire list of select
-	// statements.
-	index int
+	cancel   func()
+	nonce    string
+	response chan cache.Response
 }
 
-// Cancel calls terminate and cancel
-func (w *watch) Cancel() {
+// close cancels an open watch
+func (w *watch) close() {
 	if w.cancel != nil {
 		w.cancel()
 	}