Add a lru cache that implements the store interface

Signed-off-by: Soule BA <[email protected]>

cache/cache.go

@@ -17,7 +17,6 @@ limitations under the License.
 package cache
 
 import (
-	"fmt"
 	"sync"
 	"time"
 )
@@ -71,11 +70,12 @@ func New[T any](maxItems int, keyFunc KeyFunc[T], interval time.Duration) *Cache
 	return C
 }
 
+// Close closes the cache. It also stops the expiration eviction process.
 func (c *Cache[T]) Close() error {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	if c.closed {
-		return fmt.Errorf("cache already closed")
+		return ErrClosed
 	}
 	c.janitor.stop <- true
 	c.closed = true
@@ -92,21 +92,23 @@ func (c *Cache[T]) Add(object T) error {
 	}
 
 	c.mu.Lock()
-	defer c.mu.Unlock()
 	if c.closed {
-		return KeyError{object, fmt.Errorf("cache already closed")}
+		c.mu.Unlock()
+		return KeyError{object, ErrClosed}
 	}
 	_, found := c.Items[key]
 	if found {
-		return KeyError{object, fmt.Errorf("key already exists")}
+		c.mu.Unlock()
+		return KeyError{object, ErrAlreadyExists}
 	}
 
 	if c.MaxItems > 0 && len(c.Items) < c.MaxItems {
 		c.set(key, object)
+		c.mu.Unlock()
 		return nil
 	}
-
-	return KeyError{object, fmt.Errorf("Cache[T] is full")}
+	c.mu.Unlock()
+	return KeyError{object, ErrFull}
 }
 
 // Update adds an item to the cache, replacing any existing item.
@@ -118,22 +120,24 @@ func (c *Cache[T]) Update(object T) error {
 	}
 
 	c.mu.Lock()
-	defer c.mu.Unlock()
 	if c.closed {
-		return KeyError{object, fmt.Errorf("cache already closed")}
+		c.mu.Unlock()
+		return KeyError{object, ErrClosed}
 	}
 	_, found := c.Items[key]
 	if found {
 		c.set(key, object)
+		c.mu.Unlock()
 		return nil
 	}
 
 	if c.MaxItems > 0 && len(c.Items) < c.MaxItems {
 		c.set(key, object)
+		c.mu.Unlock()
 		return nil
 	}
-
-	return KeyError{object, fmt.Errorf("Cache[T] is full")}
+	c.mu.Unlock()
+	return KeyError{object, ErrFull}
 }
 
 func (c *cache[T]) set(key string, object T) {
@@ -169,19 +173,22 @@ func (c *Cache[T]) GetByKey(key string) (T, bool, error) {
 func (c *cache[T]) get(key string) (T, bool, error) {
 	var res T
 	c.mu.RLock()
-	defer c.mu.RUnlock()
 	if c.closed {
-		return res, false, fmt.Errorf("cache already closed")
+		c.mu.RUnlock()
+		return res, false, ErrClosed
 	}
 	item, found := c.Items[key]
 	if !found {
+		c.mu.RUnlock()
 		return res, false, nil
 	}
 	if item.Expiration > 0 {
 		if item.Expiration < time.Now().UnixNano() {
-			return res, false, fmt.Errorf("key has expired")
+			c.mu.RUnlock()
+			return res, false, ErrExpired
 		}
 	}
+	c.mu.RUnlock()
 	return item.Object, true, nil
 }
 
@@ -192,11 +199,12 @@ func (c *Cache[T]) Delete(object T) error {
 		return KeyError{object, err}
 	}
 	c.mu.Lock()
-	defer c.mu.Unlock()
 	if c.closed {
-		return KeyError{object, fmt.Errorf("cache already closed")}
+		c.mu.Unlock()
+		return KeyError{object, ErrClosed}
 	}
 	delete(c.Items, key)
+	c.mu.Unlock()
 	return nil
 }
 
@@ -206,25 +214,27 @@ func (c *Cache[T]) Delete(object T) error {
 // A closed cache cannot be cleared.
 func (c *cache[T]) Clear() {
 	c.mu.Lock()
-	defer c.mu.Unlock()
 	if c.closed {
+		c.mu.Unlock()
 		return
 	}
 	c.Items = make(map[string]Item[T])
+	c.mu.Unlock()
 }
 
 // ListKeys returns a slice of the keys in the cache.
 // If the cache is closed, ListKeys returns nil.
 func (c *cache[T]) ListKeys() []string {
 	c.mu.RLock()
-	defer c.mu.RUnlock()
 	if c.closed {
+		c.mu.RUnlock()
 		return nil
 	}
 	keys := make([]string, 0, len(c.Items))
 	for k := range c.Items {
 		keys = append(keys, k)
 	}
+	c.mu.RUnlock()
 	return keys
 }
 
@@ -236,19 +246,22 @@ func (c *Cache[T]) HasExpired(object T) (bool, error) {
 	}
 
 	c.mu.RLock()
-	defer c.mu.RUnlock()
 	if c.closed {
-		return false, KeyError{object, fmt.Errorf("cache already closed")}
+		c.mu.RUnlock()
+		return false, KeyError{object, ErrClosed}
 	}
 	item, ok := c.Items[key]
 	if !ok {
+		c.mu.RUnlock()
 		return true, nil
 	}
 	if item.Expiration > 0 {
 		if item.Expiration < time.Now().UnixNano() {
+			c.mu.RUnlock()
 			return true, nil
 		}
 	}
+	c.mu.RUnlock()
 	return false, nil
 }
 
@@ -261,15 +274,16 @@ func (c *Cache[T]) SetExpiration(object T, expiration time.Duration) error {
 	}
 
 	c.mu.Lock()
-	defer c.mu.Unlock()
 	if c.closed {
-		return KeyError{object, fmt.Errorf("cache already closed")}
+		c.mu.Unlock()
+		return KeyError{object, ErrClosed}
 	}
 	item, ok := c.Items[key]
 	if ok {
 		item.Expiration = time.Now().Add(expiration).UnixNano()
 		c.Items[key] = item
 	}
+	c.mu.Unlock()
 	return nil
 }
 
@@ -282,34 +296,38 @@ func (c *Cache[T]) GetExpiration(object T) (time.Duration, error) {
 		return 0, KeyError{object, err}
 	}
 	c.mu.RLock()
-	defer c.mu.RUnlock()
 	if c.closed {
-		return 0, KeyError{object, fmt.Errorf("cache already closed")}
+		c.mu.RUnlock()
+		return 0, KeyError{object, ErrClosed}
 	}
 	item, ok := c.Items[key]
 	if !ok {
-		return 0, KeyError{object, fmt.Errorf("key not found")}
+		c.mu.RUnlock()
+		return 0, KeyError{object, ErrNotFound}
 	}
 	if item.Expiration > 0 {
 		if item.Expiration < time.Now().UnixNano() {
-			return 0, KeyError{object, fmt.Errorf("key has expired")}
+			c.mu.RUnlock()
+			return 0, KeyError{object, ErrExpired}
 		}
 	}
+	c.mu.RUnlock()
 	return time.Duration(item.Expiration - time.Now().UnixNano()), nil
 }
 
 // DeleteExpired deletes all expired items from the cache.
 func (c *cache[T]) DeleteExpired() {
 	c.mu.Lock()
-	defer c.mu.Unlock()
 	if c.closed {
+		c.mu.Unlock()
 		return
 	}
 	for k, v := range c.Items {
 		if v.Expiration > 0 && v.Expiration < time.Now().UnixNano() {
 			delete(c.Items, k)
 		}
 	}
+	c.mu.Unlock()
 }
 
 type janitor[T any] struct {

cache/cache_test.go

@@ -20,8 +20,10 @@ import (
 	"testing"
 	"time"
 
+	"github.com/fluxcd/cli-utils/pkg/object"
 	. "github.com/onsi/gomega"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	kc "k8s.io/client-go/tools/cache"
 )
 
@@ -114,12 +116,18 @@ func TestCache(t *testing.T) {
 	t.Run("Add expiring keys", func(t *testing.T) {
 		g := NewWithT(t)
 		// new cache with a cleanup interval of 1 second
-		cache := New[NamespacedNameObject](2, NamespacedNameObjectKeyFunc, 1*time.Second)
+		cache := New[IdentifiableObject](2, IdentifiableObjectKeyFunc, 1*time.Second)
 
 		// Add an object representing an expiring token
-		obj := NamespacedNameObject{
-			Namespace: "test-ns",
-			Name:      "test",
+		obj := IdentifiableObject{
+			ObjMetadata: object.ObjMetadata{
+				Namespace: "test-ns",
+				Name:      "test",
+				GroupKind: schema.GroupKind{
+					Group: "test-group",
+					Kind:  "TestObject",
+				},
+			},
 			Object: struct {
 				token string
 			}{

cache/errors.go

@@ -18,6 +18,15 @@ package cache
 
 import "fmt"
 
+var (
+	// ErrNotFound is returned when an item is not found in the cache.
+	ErrNotFound      = fmt.Errorf("not found")
+	ErrAlreadyExists = fmt.Errorf("already exists")
+	ErrClosed        = fmt.Errorf("cache closed")
+	ErrFull          = fmt.Errorf("cache full")
+	ErrExpired       = fmt.Errorf("key has expired")
+)
+
 // KeyError will be returned any time a KeyFunc gives an error; it includes the object
 // at fault.
 type KeyError struct {

cache/go.mod

@@ -3,6 +3,7 @@ module github.com/fluxcd/pkg/cache
 go 1.22.0
 
 require (
+	github.com/fluxcd/cli-utils v0.36.0-flux.7
 	github.com/onsi/gomega v1.32.0
 	github.com/prometheus/client_golang v1.19.0
 	k8s.io/apimachinery v0.30.0
@@ -12,44 +13,55 @@ require (
 
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/blang/semver/v4 v4.0.0 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/emicklei/go-restful/v3 v3.11.0 // indirect
+	github.com/go-errors/errors v1.5.1 // indirect
 	github.com/go-logr/logr v1.4.1 // indirect
 	github.com/go-openapi/jsonpointer v0.19.6 // indirect
 	github.com/go-openapi/jsonreference v0.20.2 // indirect
-	github.com/go-openapi/swag v0.22.3 // indirect
+	github.com/go-openapi/swag v0.22.4 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/google/gnostic-models v0.6.8 // indirect
 	github.com/google/go-cmp v0.6.0 // indirect
 	github.com/google/gofuzz v1.2.0 // indirect
-	github.com/google/uuid v1.3.0 // indirect
+	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
+	github.com/google/uuid v1.6.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/monochromegane/go-gitignore v0.0.0-20200626010858-205db1a8cc00 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/prometheus/client_model v0.5.0 // indirect
 	github.com/prometheus/common v0.48.0 // indirect
 	github.com/prometheus/procfs v0.12.0 // indirect
-	golang.org/x/net v0.23.0 // indirect
-	golang.org/x/oauth2 v0.16.0 // indirect
-	golang.org/x/sys v0.18.0 // indirect
-	golang.org/x/term v0.18.0 // indirect
+	github.com/xlab/treeprint v1.2.0 // indirect
+	go.starlark.net v0.0.0-20230525235612-a134d8f9ddca // indirect
+	golang.org/x/net v0.24.0 // indirect
+	golang.org/x/oauth2 v0.19.0 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	golang.org/x/sys v0.19.0 // indirect
+	golang.org/x/term v0.19.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
-	golang.org/x/time v0.3.0 // indirect
-	google.golang.org/appengine v1.6.7 // indirect
+	golang.org/x/time v0.5.0 // indirect
 	google.golang.org/protobuf v1.33.0 // indirect
+	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/api v0.30.0 // indirect
+	k8s.io/cli-runtime v0.30.0 // indirect
 	k8s.io/klog/v2 v2.120.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20240228011516-70dd3763d340 // indirect
 	k8s.io/utils v0.0.0-20230726121419-3b25d923346b // indirect
 	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
+	sigs.k8s.io/kustomize/api v0.17.1 // indirect
+	sigs.k8s.io/kustomize/kyaml v0.17.0 // indirect
 	sigs.k8s.io/structured-merge-diff/v4 v4.4.1 // indirect
-	sigs.k8s.io/yaml v1.3.0 // indirect
+	sigs.k8s.io/yaml v1.4.0 // indirect
 )