feat: support ARC for DNS cache

common/arc/entry.go

@@ -0,0 +1,32 @@
+package arc
+
+import (
+	list "github.com/bahlo/generic-list-go"
+)
+
+type entry[K comparable, V any] struct {
+	key     K
+	value   V
+	ll      *list.List[*entry[K, V]]
+	el      *list.Element[*entry[K, V]]
+	ghost   bool
+	expires int64
+}
+
+func (e *entry[K, V]) setLRU(list *list.List[*entry[K, V]]) {
+	e.detach()
+	e.ll = list
+	e.el = e.ll.PushBack(e)
+}
+
+func (e *entry[K, V]) setMRU(list *list.List[*entry[K, V]]) {
+	e.detach()
+	e.ll = list
+	e.el = e.ll.PushFront(e)
+}
+
+func (e *entry[K, V]) detach() {
+	if e.ll != nil {
+		e.ll.Remove(e.el)
+	}
+}