private void AddNode(LFUNode node)
{
if (Head == null)
{
Head = node;
Tail = node;
Count++;
return;
}
if (Count == Capacity)
{
Set.Remove(Tail.Key);
if (Head == Tail)
{
Head = node;
Tail = node;
return;
}
Tail.Left.Right = null;
Tail = Tail.Left;
}
else
{
Count++;
}
Tail.Right = node;
node.Left = Tail;
Tail = node;
}
public void Put(int key, int value)
{
if (Capacity <= 0)
{
return;
}
if (Set.TryGetValue(key, out LFUNode node))
{
node.Value = value;
}
else
{
node = new LFUNode(key, value);
if (Capacity == 1)
{
Set.Clear();
node = new LFUNode(key, value);
Set.Add(node.Key, node);
return;
}
else
{
AddNode(node);
}
Set.Add(node.Key, node);
}
Touch(node);
}
private void Touch(LFUNode node)
{
node.Frequency++;
LFUNode parent = node.Left;
if (parent == null || parent.Frequency > node.Frequency)
{
return;
}
while (parent != null && parent.Frequency <= node.Frequency)
{
parent = parent.Left;
}
//cutoff node from its position
node.Left.Right = node.Right;
if (node.Right != null)
{
node.Right.Left = node.Left;
}
else
{
Tail = node.Left;
}
//insert node after parent
node.Left = parent;
if (parent != null)
{
node.Right = parent.Right;
parent.Right.Left = node;
parent.Right = node;
}
else
{
node.Right = Head;
Head.Left = node;
Head = node;
}
}