ROX-0000: Fix mutex taking more than 5s to unlock (stackrox#7134)

sensor/kubernetes/listener/listener.go

@@ -30,7 +30,9 @@ func New(client client.Interface, configHandler config.Handler, nodeName string,
 		traceWriter:        traceWriter,
 		outputQueue:        queue,
 		storeProvider:      storeProvider,
+		mayCreateHandlers:  concurrency.NewSignal(),
 	}
+	k.mayCreateHandlers.Signal()
 	return k
 }
 

sensor/kubernetes/listener/listener_impl.go

@@ -8,7 +8,6 @@ import (
 
 	"github.com/stackrox/rox/pkg/buildinfo"
 	"github.com/stackrox/rox/pkg/concurrency"
-	"github.com/stackrox/rox/pkg/sync"
 	"github.com/stackrox/rox/sensor/common/awscredentials"
 	"github.com/stackrox/rox/sensor/common/config"
 	"github.com/stackrox/rox/sensor/kubernetes/client"
@@ -33,13 +32,19 @@ type listenerImpl struct {
 	traceWriter        io.Writer
 	outputQueue        component.Resolver
 	storeProvider      *resources.InMemoryStoreProvider
+	mayCreateHandlers  concurrency.Signal
 	context            context.Context
-	contextMtx         sync.Mutex
 }
 
 func (k *listenerImpl) StartWithContext(ctx context.Context) error {
-	k.contextMtx.Lock()
-	defer k.contextMtx.Unlock()
+	// There is a caveat here that we need to make sure that the previous Start has already
+	// finished before swap the context, otherwise there is a risk of data racing by swapping
+	// the context while its being used to create the handlers.
+	// Since the handleAllEvents function takes too long to run, using mutex is a problem in
+	// dev environments, since the mutex will be locked to more than 5s, resulting in a panic.
+	// The current workaround is to use a signal instead of a mutex.
+	k.mayCreateHandlers.Wait()
+	k.mayCreateHandlers.Reset()
 	k.context = ctx
 	return k.Start()
 }

sensor/kubernetes/listener/resource_event_handler.go

@@ -51,9 +51,7 @@ func managedFieldsTransformer(obj interface{}) (interface{}, error) {
 }
 
 func (k *listenerImpl) handleAllEvents() {
-	k.contextMtx.Lock()
-	defer k.contextMtx.Unlock()
-
+	defer k.mayCreateHandlers.Signal()
 	// TODO(ROX-14194): remove resyncingSif once all resources are adapted
 	var resyncingSif informers.SharedInformerFactory
 	if env.ResyncDisabled.BooleanSetting() {