Improve quota sync log messages

pkg/controller/resourcequota/BUILD

@@ -29,6 +29,7 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/util/clock:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/errors:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//staging/src/k8s.io/client-go/discovery:go_default_library",
         "//staging/src/k8s.io/client-go/informers:go_default_library",

pkg/controller/resourcequota/resource_quota_controller.go

@@ -31,6 +31,7 @@ import (
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/informers"
@@ -423,15 +424,16 @@ func (rq *ResourceQuotaController) Sync(discoveryFunc NamespacedResourcesFunc, p
 			return
 		}
 
-		// Something has changed, so track the new state and perform a sync.
-		klog.V(2).Infof("syncing resource quota controller with updated resources from discovery: %v", newResources)
-		oldResources = newResources
-
 		// Ensure workers are paused to avoid processing events before informers
 		// have resynced.
 		rq.workerLock.Lock()
 		defer rq.workerLock.Unlock()
 
+		// Something has changed, so track the new state and perform a sync.
+		if klog.V(2) {
+			klog.Infof("syncing resource quota controller with updated resources from discovery: %s", printDiff(oldResources, newResources))
+		}
+
 		// Perform the monitor resync and wait for controllers to report cache sync.
 		if err := rq.resyncMonitors(newResources); err != nil {
 			utilruntime.HandleError(fmt.Errorf("failed to sync resource monitors: %v", err))
@@ -440,9 +442,30 @@ func (rq *ResourceQuotaController) Sync(discoveryFunc NamespacedResourcesFunc, p
 		if rq.quotaMonitor != nil && !controller.WaitForCacheSync("resource quota", stopCh, rq.quotaMonitor.IsSynced) {
 			utilruntime.HandleError(fmt.Errorf("timed out waiting for quota monitor sync"))
 		}
+
+		// success, remember newly synced resources
+		oldResources = newResources
+		klog.V(2).Infof("synced quota controller")
 	}, period, stopCh)
 }
 
+// printDiff returns a human-readable summary of what resources were added and removed
+func printDiff(oldResources, newResources map[schema.GroupVersionResource]struct{}) string {
+	removed := sets.NewString()
+	for oldResource := range oldResources {
+		if _, ok := newResources[oldResource]; !ok {
+			removed.Insert(fmt.Sprintf("%+v", oldResource))
+		}
+	}
+	added := sets.NewString()
+	for newResource := range newResources {
+		if _, ok := oldResources[newResource]; !ok {
+			added.Insert(fmt.Sprintf("%+v", newResource))
+		}
+	}
+	return fmt.Sprintf("added: %v, removed: %v", added.List(), removed.List())
+}
+
 // resyncMonitors starts or stops quota monitors as needed to ensure that all
 // (and only) those resources present in the map are monitored.
 func (rq *ResourceQuotaController) resyncMonitors(resources map[schema.GroupVersionResource]struct{}) error {

pkg/controller/resourcequota/resource_quota_monitor.go

@@ -284,11 +284,13 @@ func (qm *QuotaMonitor) IsSynced() bool {
 	defer qm.monitorLock.Unlock()
 
 	if len(qm.monitors) == 0 {
+		klog.V(4).Info("quota monitor not synced: no monitors")
 		return false
 	}
 
-	for _, monitor := range qm.monitors {
+	for resource, monitor := range qm.monitors {
 		if !monitor.controller.HasSynced() {
+			klog.V(4).Infof("quota monitor not synced: %v", resource)
 			return false
 		}
 	}