implement c.Keys func

mcache.go

@@ -202,7 +202,22 @@ func (src *MCache[K, V]) CopyTo(dst *MCache[K, V]) {
 	}
 }
 
-// Keys returns a slice containing the keys of the map in random order.
+func (c *MCache[K, V]) Keys() []K {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	keys := make([]K, 0, c.Count())
+
+	for k, v := range c.m {
+		if v.expireAt == nil || !v.expireAt.Before(time.Now()) {
+			keys = append(keys, k)
+		}
+	}
+
+	return keys
+}
+
+// Keys returns a slice containing the keys of the map in random order, including invalid keys if exists.
 func (c *MCache[K, V]) AllKeys() []K {
 	c.mu.RLock()
 	defer c.mu.RUnlock()