add delete by key

cache_test.go

@@ -316,6 +316,28 @@ func TestCache_Invalidate(t *testing.T) {
 	}
 }
 
+func TestCache_Delete(t *testing.T) {
+
+	caches := cachesTestList(t)
+	for _, c := range caches {
+		t.Run(strings.Replace(fmt.Sprintf("%T", c), "*lcw.", "", 1), func(t *testing.T) {
+			// fill cache
+			for i := 0; i < 1000; i++ {
+				_, err := c.Get(fmt.Sprintf("key-%d", i), func() (Value, error) {
+					return sizedString(fmt.Sprintf("result-%d", i)), nil
+				})
+				require.Nil(t, err)
+			}
+			assert.Equal(t, 1000, c.Stat().Keys)
+			assert.Equal(t, int64(9890), c.Stat().Size)
+
+			c.Delete("key-2")
+			assert.Equal(t, 999, c.Stat().Keys)
+			assert.Equal(t, int64(9890-8), c.Stat().Size)
+		})
+	}
+}
+
 func TestCache_Stats(t *testing.T) {
 	caches := cachesTestList(t)
 	for _, c := range caches {

expirable_cache.go

@@ -94,6 +94,11 @@ func (c *ExpirableCache) Purge() {
 	atomic.StoreInt64(&c.currentSize, 0)
 }
 
+// Delete cache item by key
+func (c *ExpirableCache) Delete(key string) {
+	c.backend.Delete(key)
+}
+
 // Stat returns cache statistics
 func (c *ExpirableCache) Stat() CacheStat {
 	return CacheStat{

interface.go

@@ -16,6 +16,7 @@ type LoadingCache interface {
 	Get(key string, fn func() (Value, error)) (val Value, err error) // load or get from cache
 	Peek(key string) (Value, bool)                                   // get from cache by key
 	Invalidate(fn func(key string) bool)                             // invalidate items for func(key) == true
+	Delete(key string)                                               // delete by key
 	Purge()                                                          // clear cache
 	Stat() CacheStat                                                 // cache stats
 }
@@ -55,6 +56,9 @@ func (n *Nop) Invalidate(fn func(key string) bool) {}
 // Purge does nothing for nop cache
 func (n *Nop) Purge() {}
 
+// Delete does nothing for nop cache
+func (n *Nop) Delete(key string) {}
+
 // Stat always 0s for nop cache
 func (n *Nop) Stat() CacheStat {
 	return CacheStat{}

lru_cache.go

@@ -96,6 +96,11 @@ func (c *LruCache) Invalidate(fn func(key string) bool) {
 	}
 }
 
+// Delete cache item by key
+func (c *LruCache) Delete(key string) {
+	c.backend.Remove(key)
+}
+
 // Stat returns cache statistics
 func (c *LruCache) Stat() CacheStat {
 	return CacheStat{