From a4782c8c1b832e78ee8aef3758a5ce0d27da899e Mon Sep 17 00:00:00 2001
From: Alejandro Ruiz <alejandro.ruiz@suse.com>
Date: Thu, 18 Jul 2024 17:46:19 +0200
Subject: [PATCH] perf(schema): replace LRUExpire cache

---
 pkg/internal/cache/cache.go    | 14 +++++++++--
 pkg/internal/cache/expiring.go | 46 ++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 pkg/internal/cache/expiring.go

diff --git a/pkg/internal/cache/cache.go b/pkg/internal/cache/cache.go
index bec5109f..aae6c593 100644
--- a/pkg/internal/cache/cache.go
+++ b/pkg/internal/cache/cache.go
@@ -1,6 +1,11 @@
 package cache
 
-import "time"
+import (
+	"os"
+	"time"
+)
+
+const cacheBackendEnvVar = "CATTLE_STEVE_CACHE_BACKEND"
 
 type Cache[K, V any] interface {
 	Get(K) (V, bool)
@@ -11,5 +16,10 @@ type Cache[K, V any] interface {
 }
 
 func NewCache[K, V any](maxSize int, ttl time.Duration) Cache[K, V] {
-	return newLRUExpire[K, V](maxSize, ttl)
+	switch os.Getenv(cacheBackendEnvVar) {
+	case "LRU", "lru":
+		return newLRUExpire[K, V](maxSize, ttl)
+	default:
+		return newExpiring[K, V](maxSize, ttl)
+	}
 }
diff --git a/pkg/internal/cache/expiring.go b/pkg/internal/cache/expiring.go
new file mode 100644
index 00000000..0c4ef0a6
--- /dev/null
+++ b/pkg/internal/cache/expiring.go
@@ -0,0 +1,46 @@
+package cache
+
+import (
+	"time"
+
+	"github.com/sirupsen/logrus"
+	"k8s.io/apimachinery/pkg/util/cache"
+)
+
+func newExpiring[K, V any](maxSize int, ttl time.Duration) Cache[K, V] {
+	return &wrapExpiring[K, V]{maxSize: maxSize, ttl: ttl, cache: cache.NewExpiring()}
+}
+
+// wrapExpiring imposes some static type restrictions around a generic cache.Expiring cache
+type wrapExpiring[K, V any] struct {
+	maxSize int
+	ttl     time.Duration
+	cache   *cache.Expiring
+}
+
+func (w wrapExpiring[K, V]) Get(k K) (V, bool) {
+	if v, ok := w.cache.Get(k); ok {
+		return v.(V), true
+	}
+	// zero value of V
+	return *new(V), false
+}
+
+func (w wrapExpiring[K, V]) Set(k K, v V) {
+	w.cache.Set(k, v, w.ttl)
+	if current, max := w.cache.Len(), w.maxSize; current >= max {
+		logrus.WithField("max", max).WithField("current", current).Warnf("cache reached soft limit")
+	}
+}
+
+func (w wrapExpiring[K, V]) Delete(k K) {
+	w.cache.Delete(k)
+}
+
+func (w wrapExpiring[K, V]) Len() int {
+	return w.cache.Len()
+}
+
+func (w wrapExpiring[K, V]) Reset() {
+	w.cache = cache.NewExpiring()
+}