/// <summary>
/// 清空缓存中的所有对象。
/// </summary>
public void Clear()
{
LruNormalNode <TKey, TValue> oldHead;
lock (cacheLock)
{
cacheDict.Clear();
oldHead = head;
head = null;
count = 0;
}
if (IsDisposable)
{
// 释放对象资源。
LruNormalNode <TKey, TValue> node = oldHead;
do
{
IDisposable disposable = node.Value as IDisposable;
if (disposable != null)
{
disposable.Dispose();
}
node = node.Next;
} while (node != oldHead);
}
}
/// <summary>
/// 将指定的链表节点移动到链表的头部。
/// </summary>
/// <param name="node">要移动的链表节点。</param>
private void MoveToFirst(LruNormalNode <TKey, TValue> node)
{
if (node != this.head)
{
Remove(node);
AddFirst(node);
}
}
/// <summary>
/// 将指定的节点添加到链表的头部。
/// </summary>
/// <param name="node">要添加的节点。</param>
private void AddFirst(LruNormalNode <TKey, TValue> node)
{
if (this.head == null)
{
node.Next = node.Previous = node;
}
else
{
node.Next = this.head;
node.Previous = this.head.Previous;
this.head.Previous.Next = node;
this.head.Previous = node;
}
this.head = node;
}
/// <summary>
/// 从链表中移除指定的节点。
/// </summary>
/// <param name="node">要移除的节点。</param>
private void Remove(LruNormalNode <TKey, TValue> node)
{
if (node.Next == node)
{
this.head = null;
}
else
{
node.Next.Previous = node.Previous;
node.Previous.Next = node.Next;
if (this.head == node)
{
this.head = node.Next;
}
}
}
/// <summary>
/// 将指定的键和对象添加到缓存中，并返回添加的节点。
/// </summary>
/// <param name="key">要添加的对象的键。</param>
/// <param name="value">要添加的对象。</param>
private void AddInternal(TKey key, TValue value)
{
LruNormalNode <TKey, TValue> node;
IDisposable disposable = null;
lock (cacheLock)
{
if (cacheDict.TryGetValue(key, out node))
{
// 移动旧节点。
MoveToFirst(node);
node.Value = value;
}
else
{
if (count >= maxSize)
{
// 淘汰旧节点。
node = this.head.Previous;
cacheDict.Remove(node.Key);
disposable = node.Value as IDisposable;
Remove(node);
node.Key = key;
node.Value = value;
}
else
{
node = new LruNormalNode <TKey, TValue>(key, value);
count++;
}
AddFirst(node);
cacheDict.Add(key, node);
}
}
if (disposable != null)
{
disposable.Dispose();
}
}