fix concurrent cache issues

pkg/cache/cache.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"fmt"
+	"sync"
 	"time"
 
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -14,15 +15,20 @@ type cacheItem struct {
 
 type ResourceCache struct {
 	resources map[string]cacheItem
+	lock      *sync.RWMutex
 }
 
 func NewCache() *ResourceCache {
 	return &ResourceCache{
 		resources: map[string]cacheItem{},
+		lock:      &sync.RWMutex{},
 	}
 }
 
 func (rc *ResourceCache) Get(obj *unstructured.Unstructured) (*unstructured.Unstructured, time.Time) {
+	rc.lock.RLock()
+	defer rc.lock.RUnlock()
+
 	existing, exists := rc.resources[rc.objectKey(obj)]
 	if !exists {
 		return nil, time.Time{}
@@ -32,13 +38,19 @@ func (rc *ResourceCache) Get(obj *unstructured.Unstructured) (*unstructured.Unst
 }
 
 func (rc *ResourceCache) Set(obj *unstructured.Unstructured) {
+	rc.lock.Lock()
+	defer rc.lock.Unlock()
+
 	rc.resources[rc.objectKey(obj)] = cacheItem{
 		resource: obj.DeepCopy(),
 		lastSeen: time.Now(),
 	}
 }
 
 func (rc *ResourceCache) Delete(obj *unstructured.Unstructured) {
+	rc.lock.Lock()
+	defer rc.lock.Unlock()
+
 	delete(rc.resources, rc.objectKey(obj))
 }