Tidy up usage of channels for signaling

This started as a small effort to simplify the usage of "ready" channel
in nfd-master. It extended into a wider simplification/unification of
the channel usage.

Author: marquiz

pkg/nfd-gc/nfd-gc_test.go

@@ -40,7 +40,7 @@ func TestNRTGC(t *testing.T) {
 	Convey("When theres is old NRT ", t, func() {
 		gc := newMockGC(nil, []string{"node1"})
 
-		errChan := make(chan error, 1)
+		errChan := make(chan error)
 		go func() { errChan <- gc.Run() }()
 
 		So(waitForNRT(gc.topoClient), ShouldBeTrue)
@@ -51,7 +51,7 @@ func TestNRTGC(t *testing.T) {
 	Convey("When theres is one old NRT and one up to date", t, func() {
 		gc := newMockGC([]string{"node1"}, []string{"node1", "node2"})
 
-		errChan := make(chan error, 1)
+		errChan := make(chan error)
 		go func() { errChan <- gc.Run() }()
 
 		So(waitForNRT(gc.topoClient, "node1"), ShouldBeTrue)
@@ -62,7 +62,7 @@ func TestNRTGC(t *testing.T) {
 	Convey("Should react to delete event", t, func() {
 		gc := newMockGC([]string{"node1", "node2"}, []string{"node1", "node2"})
 
-		errChan := make(chan error, 1)
+		errChan := make(chan error)
 		go func() { errChan <- gc.Run() }()
 
 		err := gc.k8sClient.CoreV1().Nodes().Delete(context.TODO(), "node1", metav1.DeleteOptions{})
@@ -81,7 +81,7 @@ func TestNRTGC(t *testing.T) {
 			},
 		}
 
-		errChan := make(chan error, 1)
+		errChan := make(chan error)
 		go func() { errChan <- gc.Run() }()
 
 		_, err := gc.topoClient.TopologyV1alpha2().NodeResourceTopologies().Create(context.TODO(), &nrt, metav1.CreateOptions{})
@@ -98,7 +98,7 @@ func newMockGC(nodes, nrts []string) *mockGC {
 			factory:    informers.NewSharedInformerFactory(k8sClient, 5*time.Minute),
 			nfdClient:  fakenfdclientset.NewSimpleClientset(),
 			topoClient: faketopologyv1alpha2.NewSimpleClientset(createFakeNRTs(nrts...)...),
-			stopChan:   make(chan struct{}, 1),
+			stopChan:   make(chan struct{}),
 			args: &Args{
 				GCPeriod: 10 * time.Minute,
 			},

pkg/nfd-master/nfd-api-controller.go

@@ -55,7 +55,7 @@ func init() {
 
 func newNfdController(config *restclient.Config, nfdApiControllerOptions nfdApiControllerOptions) (*nfdController, error) {
 	c := &nfdController{
-		stopChan:           make(chan struct{}, 1),
+		stopChan:           make(chan struct{}),
 		updateAllNodesChan: make(chan struct{}, 1),
 		updateOneNodeChan:  make(chan string),
 	}

pkg/nfd-master/nfd-master-internal_test.go

@@ -68,7 +68,7 @@ func newTestNode() *corev1.Node {
 
 func newFakeNfdAPIController(client *fakenfdclient.Clientset) *nfdController {
 	c := &nfdController{
-		stopChan:           make(chan struct{}, 1),
+		stopChan:           make(chan struct{}),
 		updateAllNodesChan: make(chan struct{}, 1),
 		updateOneNodeChan:  make(chan string),
 	}

pkg/nfd-master/nfd-master.go

@@ -149,7 +149,7 @@ type nfdMaster struct {
 	server          *grpc.Server
 	healthServer    *grpc.Server
 	stop            chan struct{}
-	ready           chan bool
+	ready           chan struct{}
 	k8sClient       k8sclient.Interface
 	nodeUpdaterPool *nodeUpdaterPool
 	deniedNs
@@ -161,8 +161,8 @@ func NewNfdMaster(args *Args) (NfdMaster, error) {
 	nfd := &nfdMaster{args: *args,
 		nodeName:  utils.NodeName(),
 		namespace: utils.GetKubernetesNamespace(),
-		ready:     make(chan bool, 1),
-		stop:      make(chan struct{}, 1),
+		ready:     make(chan struct{}),
+		stop:      make(chan struct{}),
 	}
 
 	if args.Instance != "" {
@@ -272,7 +272,7 @@ func (m *nfdMaster) Run() error {
 	}
 
 	// Run gRPC server
-	grpcErr := make(chan error, 1)
+	grpcErr := make(chan error)
 	// If the NodeFeature API is enabled, don'tregister the labeler API
 	// server. Otherwise, register the labeler server.
 	if !features.NFDFeatureGate.Enabled(features.NodeFeatureAPI) {
@@ -296,7 +296,6 @@ func (m *nfdMaster) Run() error {
 	}
 
 	// Notify that we're ready to accept connections
-	m.ready <- true
 	close(m.ready)
 
 	// NFD-Master main event loop
@@ -397,7 +396,7 @@ func (m *nfdMaster) runGrpcServer(errChan chan<- error) {
 	klog.InfoS("gRPC server serving", "port", m.args.Port)
 
 	// Run gRPC server
-	grpcErr := make(chan error, 1)
+	grpcErr := make(chan error)
 	go func() {
 		defer lis.Close()
 		grpcErr <- m.server.Serve(lis)
@@ -475,15 +474,10 @@ func (m *nfdMaster) Stop() {
 // Wait until NfdMaster is able able to accept connections.
 func (m *nfdMaster) WaitForReady(timeout time.Duration) bool {
 	select {
-	case ready, ok := <-m.ready:
-		// Ready if the flag is true or the channel has been closed
-		if ready || !ok {
-			return true
-		}
+	case <-m.ready:
+		return true
 	case <-time.After(timeout):
-		return false
 	}
-	// We should never end-up here
 	return false
 }
 

pkg/nfd-topology-updater/nfd-topology-updater.go

@@ -111,7 +111,7 @@ func NewTopologyUpdater(args Args, resourcemonitorArgs resourcemonitor.Args) (Nf
 	nfd := &nfdTopologyUpdater{
 		args:                args,
 		resourcemonitorArgs: resourcemonitorArgs,
-		stop:                make(chan struct{}, 1),
+		stop:                make(chan struct{}),
 		nodeName:            utils.NodeName(),
 		eventSource:         eventSource,
 		config:              &NFDConfig{},
@@ -207,7 +207,6 @@ func (w *nfdTopologyUpdater) Run() error {
 	// CAUTION: these resources are expected to change rarely - if ever.
 	// So we are intentionally do this once during the process lifecycle.
 	// TODO: Obtain node resources dynamically from the podresource API
-	// zonesChannel := make(chan v1alpha1.ZoneList)
 	var zones v1alpha2.ZoneList
 
 	excludeList := resourcemonitor.NewExcludeResourceList(w.config.ExcludeList, w.nodeName)
@@ -216,7 +215,7 @@ func (w *nfdTopologyUpdater) Run() error {
 		return fmt.Errorf("failed to obtain node resource information: %w", err)
 	}
 
-	grpcErr := make(chan error, 1)
+	grpcErr := make(chan error)
 
 	// Start gRPC server for liveness probe (at this point we're "live")
 	if w.args.GrpcHealthPort != 0 {

pkg/nfd-worker/nfd-worker.go

@@ -146,7 +146,7 @@ func NewNfdWorker(args *Args) (NfdWorker, error) {
 		args:                *args,
 		config:              &NFDConfig{},
 		kubernetesNamespace: utils.GetKubernetesNamespace(),
-		stop:                make(chan struct{}, 1),
+		stop:                make(chan struct{}),
 	}
 
 	// Check TLS related args
@@ -290,7 +290,7 @@ func (w *nfdWorker) Run() error {
 		return nil
 	}
 
-	grpcErr := make(chan error, 1)
+	grpcErr := make(chan error)
 
 	// Start gRPC server for liveness probe (at this point we're "live")
 	if w.args.GrpcHealthPort != 0 {