From e26e333b7e084a20e4a2d854626da5d3906e1fe1 Mon Sep 17 00:00:00 2001
From: Erik Wilson <Erik.E.Wilson@gmail.com>
Date: Wed, 7 Oct 2020 12:35:44 -0700
Subject: [PATCH] Add network policy controller CacheSyncOrTimeout

---
 pkg/agent/netpol/network_policy_controller.go |  4 ++++
 pkg/agent/netpol/utils.go                     | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/pkg/agent/netpol/network_policy_controller.go b/pkg/agent/netpol/network_policy_controller.go
index b18b806f68..5e729674cb 100644
--- a/pkg/agent/netpol/network_policy_controller.go
+++ b/pkg/agent/netpol/network_policy_controller.go
@@ -1683,6 +1683,10 @@ func NewNetworkPolicyController(
 	npInformer := informerFactory.Networking().V1().NetworkPolicies().Informer()
 	informerFactory.Start(stopCh)
 
+	if err := CacheSyncOrTimeout(informerFactory, stopCh, 1*time.Minute); err != nil {
+		return nil, errors.New("Failed to synchronize cache: " + err.Error())
+	}
+
 	// if config.MetricsEnabled {
 	// 	//Register the metrics for this controller
 	// 	prometheus.MustRegister(metrics.ControllerIPtablesSyncTime)
diff --git a/pkg/agent/netpol/utils.go b/pkg/agent/netpol/utils.go
index 1ba3c3cc58..f263581724 100644
--- a/pkg/agent/netpol/utils.go
+++ b/pkg/agent/netpol/utils.go
@@ -12,8 +12,10 @@ import (
 	"net"
 	"os/exec"
 	"strings"
+	"time"
 
 	apiv1 "k8s.io/api/core/v1"
+	"k8s.io/client-go/informers"
 )
 
 var (
@@ -537,3 +539,19 @@ func GetNodeIP(node *apiv1.Node) (net.IP, error) {
 	}
 	return nil, errors.New("host IP unknown")
 }
+
+// CacheSync performs cache synchronization under timeout limit
+func CacheSyncOrTimeout(informerFactory informers.SharedInformerFactory, stopCh <-chan struct{}, cacheSyncTimeout time.Duration) error {
+	syncOverCh := make(chan struct{})
+	go func() {
+		informerFactory.WaitForCacheSync(stopCh)
+		close(syncOverCh)
+	}()
+
+	select {
+	case <-time.After(cacheSyncTimeout):
+		return errors.New(cacheSyncTimeout.String() + " timeout")
+	case <-syncOverCh:
+		return nil
+	}
+}