fix: prevent memory leak by periodically cleaning up expired cache entries

Signed-off-by: Armando Ruocco <[email protected]>

Author: armru

internal/cnpgi/instance/internal/client/client.go

@@ -36,6 +36,9 @@ import (
 // DefaultTTLSeconds is the default TTL in seconds of cache entries
 const DefaultTTLSeconds = 10
 
+// DefaultCleanupIntervalSeconds is the default interval in seconds for cache cleanup
+const DefaultCleanupIntervalSeconds = 30
+
 type cachedEntry struct {
 	entry         client.Object
 	fetchUnixTime int64
@@ -49,18 +52,28 @@ func (e *cachedEntry) isExpired() bool {
 // ExtendedClient is an extended client that is capable of caching multiple secrets without relying on informers
 type ExtendedClient struct {
 	client.Client
-	cachedObjects []cachedEntry
-	mux           *sync.Mutex
+	cachedObjects   []cachedEntry
+	mux             *sync.Mutex
+	cleanupInterval time.Duration
 }
 
-// NewExtendedClient returns an extended client capable of caching secrets on the 'Get' operation
+// NewExtendedClient returns an extended client capable of caching secrets on the 'Get' operation.
+// It starts a background goroutine that periodically cleans up expired cache entries.
+// The cleanup routine will stop when the provided context is cancelled.
 func NewExtendedClient(
+	ctx context.Context,
 	baseClient client.Client,
 ) client.Client {
-	return &ExtendedClient{
-		Client: baseClient,
-		mux:    &sync.Mutex{},
+	ec := &ExtendedClient{
+		Client:          baseClient,
+		mux:             &sync.Mutex{},
+		cleanupInterval: DefaultCleanupIntervalSeconds * time.Second,
 	}
+
+	// Start the background cleanup routine
+	go ec.startCleanupRoutine(ctx)
+
+	return ec
 }
 
 func (e *ExtendedClient) isObjectCached(obj client.Object) bool {
@@ -208,3 +221,54 @@ func (e *ExtendedClient) Patch(
 
 	return e.Client.Patch(ctx, obj, patch, opts...)
 }
+
+// startCleanupRoutine periodically removes expired entries from the cache.
+// It runs until the context is cancelled.
+func (e *ExtendedClient) startCleanupRoutine(ctx context.Context) {
+	contextLogger := log.FromContext(ctx).WithName("extended_client_cleanup")
+	ticker := time.NewTicker(e.cleanupInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			contextLogger.Debug("stopping cache cleanup routine")
+			return
+		case <-ticker.C:
+			// Check context before cleanup to avoid unnecessary work during shutdown
+			if ctx.Err() != nil {
+				return
+			}
+			e.cleanupExpiredEntries(ctx)
+		}
+	}
+}
+
+// cleanupExpiredEntries removes all expired entries from the cache.
+func (e *ExtendedClient) cleanupExpiredEntries(ctx context.Context) {
+	contextLogger := log.FromContext(ctx).WithName("extended_client_cleanup")
+
+	e.mux.Lock()
+	defer e.mux.Unlock()
+
+	initialCount := len(e.cachedObjects)
+	if initialCount == 0 {
+		return
+	}
+
+	// Create a new slice with only non-expired entries
+	validEntries := make([]cachedEntry, 0, initialCount)
+	for _, entry := range e.cachedObjects {
+		if !entry.isExpired() {
+			validEntries = append(validEntries, entry)
+		}
+	}
+
+	removedCount := initialCount - len(validEntries)
+	if removedCount > 0 {
+		e.cachedObjects = validEntries
+		contextLogger.Debug("cleaned up expired cache entries",
+			"removedCount", removedCount,
+			"remainingCount", len(validEntries))
+	}
+}

internal/cnpgi/instance/internal/client/client_test.go

@@ -20,6 +20,7 @@ SPDX-License-Identifier: Apache-2.0
 package client
 
 import (
+	"context"
 	"time"
 
 	corev1 "k8s.io/api/core/v1"
@@ -59,6 +60,7 @@ var _ = Describe("ExtendedClient Get", func() {
 		extendedClient *ExtendedClient
 		secretInClient *corev1.Secret
 		objectStore    *barmancloudv1.ObjectStore
+		cancelCtx      context.CancelFunc
 	)
 
 	BeforeEach(func() {
@@ -79,7 +81,14 @@ var _ = Describe("ExtendedClient Get", func() {
 		baseClient := fake.NewClientBuilder().
 			WithScheme(scheme).
 			WithObjects(secretInClient, objectStore).Build()
-		extendedClient = NewExtendedClient(baseClient).(*ExtendedClient)
+		ctx, cancel := context.WithCancel(context.Background())
+		cancelCtx = cancel
+		extendedClient = NewExtendedClient(ctx, baseClient).(*ExtendedClient)
+	})
+
+	AfterEach(func() {
+		// Cancel the context to stop the cleanup routine
+		cancelCtx()
 	})
 
 	It("returns secret from cache if not expired", func(ctx SpecContext) {
@@ -164,3 +173,139 @@ var _ = Describe("ExtendedClient Get", func() {
 			Expect(objectStore.GetResourceVersion()).To(Equal("from cache"))
 		})
 })
+
+var _ = Describe("ExtendedClient Cache Cleanup", func() {
+	var (
+		extendedClient *ExtendedClient
+		cancelCtx      context.CancelFunc
+	)
+
+	BeforeEach(func() {
+		baseClient := fake.NewClientBuilder().
+			WithScheme(scheme).
+			Build()
+		ctx, cancel := context.WithCancel(context.Background())
+		cancelCtx = cancel
+		extendedClient = NewExtendedClient(ctx, baseClient).(*ExtendedClient)
+	})
+
+	AfterEach(func() {
+		cancelCtx()
+	})
+
+	It("cleans up expired entries", func(ctx SpecContext) {
+		// Add some expired entries
+		expiredSecret1 := &corev1.Secret{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "expired-secret-1",
+			},
+		}
+		expiredSecret2 := &corev1.Secret{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "expired-secret-2",
+			},
+		}
+		validSecret := &corev1.Secret{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "valid-secret",
+			},
+		}
+
+		// Add expired entries (2 minutes ago)
+		addToCache(extendedClient, expiredSecret1, time.Now().Add(-2*time.Minute).Unix())
+		addToCache(extendedClient, expiredSecret2, time.Now().Add(-2*time.Minute).Unix())
+		// Add valid entry (just now)
+		addToCache(extendedClient, validSecret, time.Now().Unix())
+
+		Expect(extendedClient.cachedObjects).To(HaveLen(3))
+
+		// Trigger cleanup
+		extendedClient.cleanupExpiredEntries(ctx)
+
+		// Only the valid entry should remain
+		Expect(extendedClient.cachedObjects).To(HaveLen(1))
+		Expect(extendedClient.cachedObjects[0].entry.GetName()).To(Equal("valid-secret"))
+	})
+
+	It("does nothing when all entries are valid", func(ctx SpecContext) {
+		validSecret1 := &corev1.Secret{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "valid-secret-1",
+			},
+		}
+		validSecret2 := &corev1.Secret{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "valid-secret-2",
+			},
+		}
+
+		addToCache(extendedClient, validSecret1, time.Now().Unix())
+		addToCache(extendedClient, validSecret2, time.Now().Unix())
+
+		Expect(extendedClient.cachedObjects).To(HaveLen(2))
+
+		// Trigger cleanup
+		extendedClient.cleanupExpiredEntries(ctx)
+
+		// Both entries should remain
+		Expect(extendedClient.cachedObjects).To(HaveLen(2))
+	})
+
+	It("does nothing when cache is empty", func(ctx SpecContext) {
+		Expect(extendedClient.cachedObjects).To(BeEmpty())
+
+		// Trigger cleanup
+		extendedClient.cleanupExpiredEntries(ctx)
+
+		Expect(extendedClient.cachedObjects).To(BeEmpty())
+	})
+
+	It("removes all entries when all are expired", func(ctx SpecContext) {
+		expiredSecret1 := &corev1.Secret{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "expired-secret-1",
+			},
+		}
+		expiredSecret2 := &corev1.Secret{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "expired-secret-2",
+			},
+		}
+
+		addToCache(extendedClient, expiredSecret1, time.Now().Add(-2*time.Minute).Unix())
+		addToCache(extendedClient, expiredSecret2, time.Now().Add(-2*time.Minute).Unix())
+
+		Expect(extendedClient.cachedObjects).To(HaveLen(2))
+
+		// Trigger cleanup
+		extendedClient.cleanupExpiredEntries(ctx)
+
+		Expect(extendedClient.cachedObjects).To(BeEmpty())
+	})
+
+	It("stops cleanup routine when context is cancelled", func() {
+		// Create a new client with a short cleanup interval for testing
+		baseClient := fake.NewClientBuilder().
+			WithScheme(scheme).
+			Build()
+		ctx, cancel := context.WithCancel(context.Background())
+		ec := NewExtendedClient(ctx, baseClient).(*ExtendedClient)
+		ec.cleanupInterval = 10 * time.Millisecond
+
+		// Cancel the context immediately
+		cancel()
+
+		// Give the goroutine time to stop
+		time.Sleep(50 * time.Millisecond)
+
+		// The goroutine should have stopped gracefully (no panic or hanging)
+		// This test mainly verifies the cleanup routine respects context cancellation
+	})
+})

internal/cnpgi/instance/manager.go

@@ -84,7 +84,7 @@ func Start(ctx context.Context) error {
 		return err
 	}
 
-	customCacheClient := extendedclient.NewExtendedClient(mgr.GetClient())
+	customCacheClient := extendedclient.NewExtendedClient(ctx, mgr.GetClient())
 
 	if err := mgr.Add(&CNPGI{
 		Client:         customCacheClient,