实现open file cache

internal/utils/linkedlist/list.go

@@ -0,0 +1,93 @@
+// Copyright 2022 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package linkedlist
+
+type List struct {
+	head  *Item
+	end   *Item
+	count int
+}
+
+func NewList() *List {
+	return &List{}
+}
+
+func (this *List) Head() *Item {
+	return this.head
+}
+
+func (this *List) End() *Item {
+	return this.end
+}
+
+func (this *List) Push(item *Item) {
+	if item == nil {
+		return
+	}
+
+	// 如果已经在末尾了，则do nothing
+	if this.end == item {
+		return
+	}
+
+	if item.prev != nil || item.next != nil || this.head == item {
+		this.Remove(item)
+	}
+	this.add(item)
+}
+
+func (this *List) Remove(item *Item) {
+	if item == nil {
+		return
+	}
+	if item.prev != nil {
+		item.prev.next = item.next
+	}
+	if item.next != nil {
+		item.next.prev = item.prev
+	}
+	if item == this.head {
+		this.head = item.next
+	}
+	if item == this.end {
+		this.end = item.prev
+	}
+
+	item.prev = nil
+	item.next = nil
+	this.count--
+}
+
+func (this *List) Len() int {
+	return this.count
+}
+
+func (this *List) Range(f func(item *Item) (goNext bool)) {
+	for e := this.head; e != nil; e = e.next {
+		goNext := f(e)
+		if !goNext {
+			break
+		}
+	}
+}
+
+func (this *List) Reset() {
+	this.head = nil
+	this.end = nil
+}
+
+func (this *List) add(item *Item) {
+	if item == nil {
+		return
+	}
+	if this.end != nil {
+		this.end.next = item
+		item.prev = this.end
+		item.next = nil
+	}
+	this.end = item
+	if this.head == nil {
+		this.head = item
+	}
+	this.count++
+}