Add .Clear() to linked.Hashmap (#2917)

cache/lru_cache.go

@@ -92,7 +92,9 @@ func (c *LRU[K, _]) evict(key K) {
 }
 
 func (c *LRU[K, V]) flush() {
-	c.elements = linked.NewHashmap[K, V]()
+	if c.elements != nil {
+		c.elements.Clear()
+	}
 }
 
 func (c *LRU[_, _]) len() int {

cache/lru_sized_cache.go

@@ -113,7 +113,7 @@ func (c *sizedLRU[K, _]) evict(key K) {
 }
 
 func (c *sizedLRU[K, V]) flush() {
-	c.elements = linked.NewHashmap[K, V]()
+	c.elements.Clear()
 	c.currentSize = 0
 }
 

utils/linked/hashmap.go

@@ -63,14 +63,25 @@ func (lh *Hashmap[K, V]) Get(key K) (V, bool) {
 func (lh *Hashmap[K, V]) Delete(key K) bool {
 	e, ok := lh.entryMap[key]
 	if ok {
-		lh.entryList.Remove(e)
-		delete(lh.entryMap, key)
-		e.Value = keyValue[K, V]{} // Free the key value pair
-		lh.freeList = append(lh.freeList, e)
+		lh.remove(e)
 	}
 	return ok
 }
 
+func (lh *Hashmap[K, V]) Clear() {
+	for _, e := range lh.entryMap {
+		lh.remove(e)
+	}
+}
+
+// remove assumes that [e] is currently in the Hashmap.
+func (lh *Hashmap[K, V]) remove(e *ListElement[keyValue[K, V]]) {
+	delete(lh.entryMap, e.Value.key)
+	lh.entryList.Remove(e)
+	e.Value = keyValue[K, V]{} // Free the key value pair
+	lh.freeList = append(lh.freeList, e)
+}
+
 func (lh *Hashmap[K, V]) Len() int {
 	return len(lh.entryMap)
 }

utils/linked/hashmap_test.go

@@ -95,6 +95,23 @@ func TestHashmap(t *testing.T) {
 	require.Equal(1, val1, "wrong value")
 }
 
+func TestHashmapClear(t *testing.T) {
+	require := require.New(t)
+
+	lh := NewHashmap[int, int]()
+	lh.Put(1, 1)
+	lh.Put(2, 2)
+
+	lh.Clear()
+
+	require.Empty(lh.entryMap)
+	require.Zero(lh.entryList.Len())
+	require.Len(lh.freeList, 2)
+	for _, e := range lh.freeList {
+		require.Zero(e.Value) // Make sure the value is cleared
+	}
+}
+
 func TestIterator(t *testing.T) {
 	require := require.New(t)
 	id1, id2, id3 := ids.GenerateTestID(), ids.GenerateTestID(), ids.GenerateTestID()