Merge pull request #8 from Code-Hex/fix/referenced-item

fixed referenced item

Author: Code-Hex

cache.go

@@ -24,6 +24,8 @@ type Item[K comparable, V any] struct {
 	ReferencedAt   time.Time
 }
 
+// Referenced increments a reference counter and updates `ReferencedAt`
+// to current time.
 func (i *Item[K, V]) Referenced() {
 	i.ReferenceCount++
 	i.ReferencedAt = nowFunc()

lru/lru.go

@@ -43,6 +43,7 @@ func (c *Cache[K, V]) Get(key K) (zero V, _ bool) {
 	if item.HasExpired() {
 		return
 	}
+	item.Referenced()
 	// updates cache order
 	c.list.MoveToFront(e)
 	return item.Value, true
@@ -56,7 +57,9 @@ func (c *Cache[K, V]) Set(key K, val V, opts ...cache.ItemOption) {
 	if e, ok := c.items[key]; ok {
 		// updates cache order
 		c.list.MoveToFront(e)
-		e.Value.(*cache.Item[K, V]).Value = val
+		item := e.Value.(*cache.Item[K, V])
+		item.Value = val
+		item.Referenced()
 		return
 	}
 

simple/example_test.go

@@ -23,11 +23,16 @@ func ExampleCache() {
 	if !aok2 {
 		fmt.Println("key 'a' has been deleted")
 	}
+	// update
+	c.Set("b", 3)
+	newbv, _ := c.Get("b")
+	fmt.Println(newbv)
 	// Output:
 	// 1 true
 	// 2 true
 	// 0 false
 	// key 'a' has been deleted
+	// 3
 }
 
 func ExampleCacheKeys() {

simple/simple.go

@@ -26,8 +26,13 @@ func NewCache[K comparable, V any]() *Cache[K, V] {
 // The default item never expires.
 func (c *Cache[K, V]) Set(k K, v V, opts ...cache.ItemOption) {
 	c.mu.Lock()
+	defer c.mu.Unlock()
+	if item, ok := c.items[k]; ok {
+		item.Value = v
+		item.Referenced()
+		return
+	}
 	c.items[k] = cache.NewItem(k, v, opts...)
-	c.mu.Unlock()
 }
 
 // Get gets an item from the cache.
@@ -43,6 +48,7 @@ func (c *Cache[K, V]) Get(k K) (val V, ok bool) {
 	if got.HasExpired() {
 		return
 	}
+	got.Referenced()
 	return got.Value, true
 }