Enhancement: Add watch poll interval to KV storage backend

* Introduced a new `WatchPollInterval` option in `KVBackendOptions` to configure the polling frequency for new events.
* Updated the `NewKVStorageBackend` function to utilize the specified `WatchPollInterval`, defaulting to a predefined value if not set.
* Adjusted the event watching mechanism to respect the configured polling interval.

pkg/storage/unified/apistore/restoptions.go

@@ -63,6 +63,7 @@ func NewRESTOptionsGetterMemory(originalStorageConfig storagebackend.Config, sec
 	backend, err := resource.NewKVStorageBackend(resource.KVBackendOptions{
 		KvStore:                      kv,
 		WithExperimentalClusterScope: true,
+		WatchPollInterval:            5 * time.Minute,
 	})
 	if err != nil {
 		return nil, err

pkg/storage/unified/resource/storage_backend.go

@@ -62,6 +62,7 @@ type kvStorageBackend struct {
 	withPruner                   bool
 	eventRetentionPeriod         time.Duration
 	eventPruningInterval         time.Duration
+	watchPollInterval            time.Duration
 	historyPruner                Pruner
 	withExperimentalClusterScope bool
 	//tracer        trace.Tracer
@@ -76,6 +77,7 @@ type KVBackendOptions struct {
 	WithExperimentalClusterScope bool                  // Allow empty namespace to be used for cluster-scoped resources.
 	EventRetentionPeriod         time.Duration         // How long to keep events (default: 1 hour)
 	EventPruningInterval         time.Duration         // How often to run the event pruning (default: 5 minutes)
+	WatchPollInterval            time.Duration         // How often to poll for new events in watch (default: 100ms)
 	Tracer                       trace.Tracer          // TODO add tracing
 	Reg                          prometheus.Registerer // TODO add metrics
 }
@@ -100,6 +102,11 @@ func NewKVStorageBackend(opts KVBackendOptions) (StorageBackend, error) {
 		eventPruningInterval = defaultEventPruningInterval
 	}
 
+	watchPollInterval := opts.WatchPollInterval
+	if watchPollInterval <= 0 {
+		watchPollInterval = defaultPollInterval
+	}
+
 	backend := &kvStorageBackend{
 		kv:                           kv,
 		dataStore:                    newDataStore(kv),
@@ -110,6 +117,7 @@ func NewKVStorageBackend(opts KVBackendOptions) (StorageBackend, error) {
 		log:                          &logging.NoOpLogger{},     // Make this configurable
 		eventRetentionPeriod:         eventRetentionPeriod,
 		eventPruningInterval:         eventPruningInterval,
+		watchPollInterval:            watchPollInterval,
 		withExperimentalClusterScope: opts.WithExperimentalClusterScope,
 	}
 	err = backend.initPruner(ctx)
@@ -1170,7 +1178,9 @@ func (k *kvStorageBackend) WatchWriteEvents(ctx context.Context) (<-chan *Writte
 	// Create a channel to receive events
 	events := make(chan *WrittenEvent, 10000) // TODO: make this configurable
 
-	notifierEvents := k.notifier.Watch(ctx, defaultWatchOptions())
+	watchOpts := defaultWatchOptions()
+	watchOpts.PollInterval = k.watchPollInterval
+	notifierEvents := k.notifier.Watch(ctx, watchOpts)
 	go func() {
 		for event := range notifierEvents {
 			// fetch the data