topology-updater: make it possible to disable sleep-interval

Especially convenient for testing porpuses and
completely harmless

Signed-off-by: Talor Itzhak <titzhak@redhat.com>

cmd/nfd-topology-updater/main.go

@@ -134,7 +134,7 @@ func initFlags(flagset *flag.FlagSet) (*topology.Args, *resourcemonitor.Args) {
 	flagset.StringVar(&args.KubeConfigFile, "kubeconfig", "",
 		"Kube config file.")
 	flagset.DurationVar(&resourcemonitorArgs.SleepInterval, "sleep-interval", time.Duration(60)*time.Second,
-		"Time to sleep between CR updates. Non-positive value implies no CR updatation (i.e. infinite sleep). [Default: 60s]")
+		"Time to sleep between CR updates. zero means no CR updates on interval basis. [Default: 60s]")
 	flagset.StringVar(&resourcemonitorArgs.Namespace, "watch-namespace", "*",
 		"Namespace to watch pods (for testing/debugging purpose). Use * for all namespaces.")
 	flagset.StringVar(&resourcemonitorArgs.KubeletConfigURI, "kubelet-config-uri", "",

docs/reference/topology-updater-commandline-reference.md

@@ -77,8 +77,7 @@ nfd-topology-updater -oneshot -no-publish
 ### -sleep-interval
 
 The `-sleep-interval` specifies the interval between resource hardware
-topology re-examination (and CR updates). A non-positive value implies
-infinite sleep interval, i.e. no re-detection is done.
+topology re-examination (and CR updates). zero means no CR updates on interval basis.
 
 Default: 60s
 

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

@@ -63,10 +63,15 @@ func New(sleepInterval time.Duration, dest chan<- Info, kubeletStateDir string)
 }
 
 func (n *Notifier) Run() {
-	t := time.Tick(n.sleepInterval)
+	timeEvents := make(<-chan time.Time)
+	if n.sleepInterval > 0 {
+		ticker := time.NewTicker(n.sleepInterval)
+		timeEvents = ticker.C
+	}
+
 	for {
 		select {
-		case <-t:
+		case <-timeEvents:
 			klog.V(5).Infof("timer update received")
 			i := Info{Event: IntervalBased}
 			n.dest <- i