From fbab1a2ea90088aca40509bd272241c4656f45cf Mon Sep 17 00:00:00 2001
From: Joel Speed <joel.speed@hotmail.co.uk>
Date: Mon, 24 Feb 2020 17:58:25 +0000
Subject: [PATCH] Use sync.Map for clusterNodeInformers

---
 .../cluster.x-k8s.io_machinehealthchecks.yaml |  2 +-
 controllers/machinehealthcheck_controller.go  | 36 +++++++++++--------
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/config/crd/bases/cluster.x-k8s.io_machinehealthchecks.yaml b/config/crd/bases/cluster.x-k8s.io_machinehealthchecks.yaml
index 6f0f3e2075cf..66e9b32e9fab 100644
--- a/config/crd/bases/cluster.x-k8s.io_machinehealthchecks.yaml
+++ b/config/crd/bases/cluster.x-k8s.io_machinehealthchecks.yaml
@@ -69,7 +69,7 @@ spec:
                 x-kubernetes-int-or-string: true
               nodeStartupTimeout:
                 description: Machines older than this duration without a node will
-                  be considered to have failed and will be remediated
+                  be considered to have failed and will be remediated.
                 type: string
               selector:
                 description: Label selector to match machines whose health will be
diff --git a/controllers/machinehealthcheck_controller.go b/controllers/machinehealthcheck_controller.go
index bc807494d3b5..6e9c9bd978ab 100644
--- a/controllers/machinehealthcheck_controller.go
+++ b/controllers/machinehealthcheck_controller.go
@@ -57,11 +57,10 @@ type MachineHealthCheckReconciler struct {
 	Client client.Client
 	Log    logr.Logger
 
-	controller               controller.Controller
-	recorder                 record.EventRecorder
-	scheme                   *runtime.Scheme
-	clusterNodeInformers     map[types.NamespacedName]cache.Informer
-	clusterNodeInformersLock *sync.Mutex
+	controller           controller.Controller
+	recorder             record.EventRecorder
+	scheme               *runtime.Scheme
+	clusterNodeInformers *sync.Map
 }
 
 func (r *MachineHealthCheckReconciler) SetupWithManager(mgr ctrl.Manager, options controller.Options) error {
@@ -101,8 +100,7 @@ func (r *MachineHealthCheckReconciler) SetupWithManager(mgr ctrl.Manager, option
 	r.controller = controller
 	r.recorder = mgr.GetEventRecorderFor("machinehealthcheck-controller")
 	r.scheme = mgr.GetScheme()
-	r.clusterNodeInformers = make(map[types.NamespacedName]cache.Informer)
-	r.clusterNodeInformersLock = &sync.Mutex{}
+	r.clusterNodeInformers = &sync.Map{}
 	return nil
 }
 
@@ -345,11 +343,9 @@ func (r *MachineHealthCheckReconciler) getMachineFromNode(nodeName string) (*clu
 
 func (r *MachineHealthCheckReconciler) watchClusterNodes(ctx context.Context, c client.Client, cluster *clusterv1.Cluster) error {
 	// Ensure that concurrent reconciles don't clash when setting up watches
-	r.clusterNodeInformersLock.Lock()
-	defer r.clusterNodeInformersLock.Unlock()
 
 	key := util.ObjectKey(cluster)
-	if _, ok := r.clusterNodeInformers[key]; ok {
+	if _, ok := r.loadClusterNodeInformer(key); ok {
 		// watch was already set up for this cluster
 		return nil
 	}
@@ -377,12 +373,24 @@ func (r *MachineHealthCheckReconciler) watchClusterNodes(ctx context.Context, c
 		return errors.Wrap(err, "error watching nodes on target cluster")
 	}
 
-	if r.clusterNodeInformers == nil {
-		r.clusterNodeInformers = make(map[types.NamespacedName]cache.Informer)
+	r.storeClusterNodeInformer(key, nodeInformer)
+	return nil
+}
+
+func (r *MachineHealthCheckReconciler) loadClusterNodeInformer(key client.ObjectKey) (cache.Informer, bool) {
+	val, ok := r.clusterNodeInformers.Load(key)
+	if !ok {
+		return nil, false
 	}
+	informer, ok := val.(cache.Informer)
+	if !ok {
+		return nil, false
+	}
+	return informer, true
+}
 
-	r.clusterNodeInformers[key] = nodeInformer
-	return nil
+func (r *MachineHealthCheckReconciler) storeClusterNodeInformer(key client.ObjectKey, nodeInformer cache.Informer) {
+	r.clusterNodeInformers.Store(key, nodeInformer)
 }
 
 func (r *MachineHealthCheckReconciler) indexMachineByNodeName(object runtime.Object) []string {