172 lines
3.4 KiB
Go
172 lines
3.4 KiB
Go
package cache
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import (
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"sync"
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"time"
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)
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const (
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// maxItems 是L1Cache的最大条目数
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// 超过此限制后将淘汰最久未使用的条目
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maxItems = 10000
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)
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// CacheItem 缓存项
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type CacheItem struct {
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Value interface{}
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Expiration int64
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}
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// Expired 判断缓存项是否过期
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func (item *CacheItem) Expired() bool {
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return item.Expiration > 0 && time.Now().UnixNano() > item.Expiration
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}
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// L1Cache L1本地缓存（支持LRU淘汰策略）
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type L1Cache struct {
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items map[string]*CacheItem
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mu sync.RWMutex
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// accessOrder 记录key的访问顺序，用于LRU淘汰
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// 第一个是最久未使用的，最后一个是最近使用的
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accessOrder []string
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}
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// NewL1Cache 创建L1缓存
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func NewL1Cache() *L1Cache {
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return &L1Cache{
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items: make(map[string]*CacheItem),
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}
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}
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// Set 设置缓存
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func (c *L1Cache) Set(key string, value interface{}, ttl time.Duration) {
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c.mu.Lock()
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defer c.mu.Unlock()
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var expiration int64
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if ttl > 0 {
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expiration = time.Now().Add(ttl).UnixNano()
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}
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// 如果key已存在，更新访问顺序
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if _, exists := c.items[key]; exists {
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c.items[key] = &CacheItem{
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Value: value,
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Expiration: expiration,
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}
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c.updateAccessOrder(key)
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return
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}
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// 检查是否超过最大容量，进行LRU淘汰
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if len(c.items) >= maxItems {
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c.evictLRU()
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}
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c.items[key] = &CacheItem{
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Value: value,
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Expiration: expiration,
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}
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c.accessOrder = append(c.accessOrder, key)
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}
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// evictLRU 淘汰最久未使用的条目
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func (c *L1Cache) evictLRU() {
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if len(c.accessOrder) == 0 {
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return
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}
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// 淘汰最久未使用的（第一个）
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oldest := c.accessOrder[0]
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delete(c.items, oldest)
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c.accessOrder = c.accessOrder[1:]
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}
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// removeFromAccessOrder 从访问顺序中移除key
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func (c *L1Cache) removeFromAccessOrder(key string) {
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for i, k := range c.accessOrder {
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if k == key {
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c.accessOrder = append(c.accessOrder[:i], c.accessOrder[i+1:]...)
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return
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}
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}
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}
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// updateAccessOrder 更新访问顺序，将key移到最后（最近使用）
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func (c *L1Cache) updateAccessOrder(key string) {
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for i, k := range c.accessOrder {
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if k == key {
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// 移除当前位置
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c.accessOrder = append(c.accessOrder[:i], c.accessOrder[i+1:]...)
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// 添加到末尾
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c.accessOrder = append(c.accessOrder, key)
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return
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}
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}
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}
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// Get 获取缓存
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func (c *L1Cache) Get(key string) (interface{}, bool) {
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c.mu.Lock()
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defer c.mu.Unlock()
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item, ok := c.items[key]
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if !ok {
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return nil, false
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}
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if item.Expired() {
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delete(c.items, key)
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c.removeFromAccessOrder(key)
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return nil, false
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}
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// 更新访问顺序
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c.updateAccessOrder(key)
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return item.Value, true
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}
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// Delete 删除缓存
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func (c *L1Cache) Delete(key string) {
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c.mu.Lock()
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defer c.mu.Unlock()
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delete(c.items, key)
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c.removeFromAccessOrder(key)
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}
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// Clear 清空缓存
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func (c *L1Cache) Clear() {
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c.mu.Lock()
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defer c.mu.Unlock()
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c.items = make(map[string]*CacheItem)
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c.accessOrder = make([]string, 0)
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}
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// Size 获取缓存大小
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func (c *L1Cache) Size() int {
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c.mu.RLock()
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defer c.mu.RUnlock()
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return len(c.items)
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}
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// Cleanup 清理过期缓存
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func (c *L1Cache) Cleanup() {
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c.mu.Lock()
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defer c.mu.Unlock()
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now := time.Now().UnixNano()
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keysToDelete := make([]string, 0)
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for key, item := range c.items {
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if item.Expiration > 0 && now > item.Expiration {
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keysToDelete = append(keysToDelete, key)
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}
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}
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for _, key := range keysToDelete {
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delete(c.items, key)
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c.removeFromAccessOrder(key)
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}
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}
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