314 lines
7.0 KiB
Go
314 lines
7.0 KiB
Go
package cache
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import (
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"container/list"
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"sync"
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"time"
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)
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// CacheOptions 缓存配置选项
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type CacheOptions struct {
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Enabled bool // 是否启用缓存
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Size int // 缓存大小，0表示无限制
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Expiration time.Duration // 缓存项过期时间，0表示永不过期
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EvictionType string // 缓存淘汰策略，支持"lru"(最近最少使用)和"fifo"(先进先出)
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Compression CompressOptions // 压缩选项
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Monitoring MonitorOptions // 监控选项
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}
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// DefaultCacheOptions 默认缓存配置
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var DefaultCacheOptions = CacheOptions{
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Enabled: true,
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Size: 100, // 默认缓存100个SVG
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Expiration: time.Hour, // 默认缓存项过期时间为1小时
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EvictionType: "lru", // 默认使用LRU淘汰策略
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Compression: DefaultCompressOptions, // 默认压缩选项
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Monitoring: DefaultMonitorOptions, // 默认监控选项
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}
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// CacheKey 缓存键结构
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type CacheKey struct {
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Id string
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SansEnv bool
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Theme int
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Part int
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}
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// CacheItem 缓存项结构
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type CacheItem struct {
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SVG string // SVG内容
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Compressed []byte // 压缩后的SVG数据
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IsCompressed bool // 是否已压缩
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CreatedAt time.Time // 创建时间
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LastUsed time.Time // 最后使用时间
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}
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// PNCache SVG缓存结构
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type PNCache struct {
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Options CacheOptions
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Items map[CacheKey]*list.Element // 存储缓存项的映射
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EvictionList *list.List // 用于实现LRU/FIFO的双向链表
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Mutex sync.RWMutex
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Hits int // 缓存命中次数
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Misses int // 缓存未命中次数
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Monitor *Monitor // 缓存监控器
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}
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// NewCache 创建一个新的缓存实例
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func NewCache(options CacheOptions) *PNCache {
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cache := &PNCache{
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Options: options,
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Items: make(map[CacheKey]*list.Element),
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EvictionList: list.New(),
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Hits: 0,
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Misses: 0,
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}
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// 如果启用了监控，创建并启动监控器
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if options.Monitoring.Enabled {
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cache.Monitor = NewMonitor(cache, options.Monitoring)
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cache.Monitor.Start()
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}
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return cache
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}
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// NewDefaultCache 使用默认配置创建一个新的缓存实例
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func NewDefaultCache() *PNCache {
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return NewCache(DefaultCacheOptions)
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}
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// Get 从缓存中获取SVG
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func (c *PNCache) Get(key CacheKey) (string, bool) {
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if !c.Options.Enabled {
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c.Misses++
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return "", false
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}
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c.Mutex.Lock() // 使用写锁以便更新LRU信息
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defer c.Mutex.Unlock()
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element, found := c.Items[key]
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if !found {
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c.Misses++
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return "", false
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}
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// 获取缓存项
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cacheItem := element.Value.(*CacheItem)
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// 检查是否过期
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if c.Options.Expiration > 0 {
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if time.Since(cacheItem.CreatedAt) > c.Options.Expiration {
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// 删除过期项
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c.EvictionList.Remove(element)
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delete(c.Items, key)
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c.Misses++
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return "", false
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}
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}
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// 更新LRU信息
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if c.Options.EvictionType == "lru" {
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cacheItem.LastUsed = time.Now()
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c.EvictionList.MoveToFront(element)
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}
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c.Hits++
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// 如果数据已压缩，需要解压缩
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if cacheItem.IsCompressed {
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svg, err := DecompressSVG(cacheItem.Compressed, true)
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if err != nil {
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// 解压失败，返回未压缩的原始数据
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return cacheItem.SVG, true
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}
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return svg, true
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}
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return cacheItem.SVG, true
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}
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// Set 将SVG存入缓存
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func (c *PNCache) Set(key CacheKey, svg string) {
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if !c.Options.Enabled {
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return
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}
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c.Mutex.Lock()
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defer c.Mutex.Unlock()
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// 尝试压缩SVG数据
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var compressed []byte
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var isCompressed bool
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// 如果启用了压缩，尝试压缩SVG
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if c.Options.Compression.Enabled {
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// 首先优化SVG
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optimizedSVG := OptimizeSVG(svg)
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// 然后压缩
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compressed, isCompressed = CompressSVG(optimizedSVG, c.Options.Compression)
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// 如果压缩成功，使用优化后的SVG
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if isCompressed {
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svg = optimizedSVG
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}
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}
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// 检查是否已存在
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if element, exists := c.Items[key]; exists {
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// 更新现有项
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cacheItem := element.Value.(*CacheItem)
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cacheItem.SVG = svg
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cacheItem.Compressed = compressed
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cacheItem.IsCompressed = isCompressed
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cacheItem.LastUsed = time.Now()
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cacheItem.CreatedAt = time.Now()
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// 如果使用LRU策略，将项移到链表前端
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if c.Options.EvictionType == "lru" {
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c.EvictionList.MoveToFront(element)
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}
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return
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}
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// 如果达到大小限制，需要淘汰一个项
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if c.Options.Size > 0 && len(c.Items) >= c.Options.Size {
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c.evictItem()
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}
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// 创建新的缓存项
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now := time.Now()
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cacheItem := &CacheItem{
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SVG: svg,
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Compressed: compressed,
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IsCompressed: isCompressed,
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CreatedAt: now,
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LastUsed: now,
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}
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// 添加到链表和映射
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element := c.EvictionList.PushFront(cacheItem)
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c.Items[key] = element
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}
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// evictItem 根据淘汰策略移除一个缓存项
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func (c *PNCache) evictItem() {
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if c.EvictionList.Len() == 0 {
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return
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}
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// 获取要淘汰的元素
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var element *list.Element
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switch c.Options.EvictionType {
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case "lru":
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// LRU策略：移除链表尾部元素（最近最少使用）
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element = c.EvictionList.Back()
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default:
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// 默认使用FIFO策略：移除链表尾部元素（最先添加）
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element = c.EvictionList.Back()
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}
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if element != nil {
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// 从链表中移除
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c.EvictionList.Remove(element)
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// 从映射中找到并删除对应的键
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for k, v := range c.Items {
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if v == element {
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delete(c.Items, k)
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break
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}
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}
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}
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}
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// Clear 清空缓存
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func (c *PNCache) Clear() {
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c.Mutex.Lock()
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defer c.Mutex.Unlock()
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c.Items = make(map[CacheKey]*list.Element)
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c.EvictionList = list.New()
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c.Hits = 0
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c.Misses = 0
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}
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// Size 返回当前缓存项数量
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func (c *PNCache) Size() int {
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c.Mutex.RLock()
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defer c.Mutex.RUnlock()
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return len(c.Items)
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}
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// Stats 返回缓存统计信息
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func (c *PNCache) Stats() (Hits, Misses int, hitRate float64) {
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c.Mutex.RLock()
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defer c.Mutex.RUnlock()
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Hits = c.Hits
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Misses = c.Misses
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total := Hits + Misses
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if total > 0 {
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hitRate = float64(Hits) / float64(total)
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}
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return
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}
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// RemoveExpired 移除所有过期的缓存项
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func (c *PNCache) RemoveExpired() int {
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if c.Options.Expiration <= 0 {
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return 0
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}
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c.Mutex.Lock()
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defer c.Mutex.Unlock()
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count := 0
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now := time.Now()
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// 遍历所有缓存项，检查是否过期
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for key, element := range c.Items {
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cacheItem := element.Value.(*CacheItem)
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if now.Sub(cacheItem.CreatedAt) > c.Options.Expiration {
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// 从链表中移除
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c.EvictionList.Remove(element)
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// 从映射中删除
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delete(c.Items, key)
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count++
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}
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}
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return count
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}
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// GetOptions 获取当前缓存选项
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func (c *PNCache) GetOptions() CacheOptions {
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c.Mutex.RLock()
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defer c.Mutex.RUnlock()
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return c.Options
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}
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// UpdateOptions 更新缓存选项
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func (c *PNCache) UpdateOptions(options CacheOptions) {
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c.Mutex.Lock()
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defer c.Mutex.Unlock()
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// 更新选项
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c.Options = options
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// 如果新的缓存大小小于当前项数，需要淘汰一些项
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if c.Options.Size > 0 && c.Options.Size < len(c.Items) {
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// 计算需要淘汰的项数
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toEvict := len(c.Items) - c.Options.Size
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// 淘汰多余的项
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for i := 0; i < toEvict; i++ {
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c.evictItem()
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}
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}
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}
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