feat: 首页增加内存缓存（30s TTL）

- 新增 internal/cache/home_cache.go，实现带 TTL 的首页文章列表内存缓存
- frontend.go 首页 handler 优先读取缓存，未命中/过期时查询 DB 并回填
- PostService 注入失效回调，在 Create/Update/Delete/Approve 后自动失效缓存
- 减少首页每次请求都查 DB 的开销

internal/cache/home_cache.go

@@ -0,0 +1,55 @@
+package cache
+
+import (
+	"sync"
+	"time"
+
+	"metazone.cc/metalab/internal/model"
+)
+
+// HomePageCache 首页内存缓存，30 秒 TTL，创建/更新/删除/审核通过时失效
+type HomePageCache struct {
+	mu      sync.RWMutex
+	posts   []model.Post
+	total   int64
+	expires time.Time
+	ttl     time.Duration
+}
+
+// NewHomePageCache 创建首页缓存，ttl 为缓存有效期
+func NewHomePageCache(ttl time.Duration) *HomePageCache {
+	return &HomePageCache{ttl: ttl}
+}
+
+// Get 返回缓存数据，ok=false 表示缓存未命中或已过期
+func (c *HomePageCache) Get() (posts []model.Post, total int64, ok bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	if time.Now().After(c.expires) {
+		return nil, 0, false
+	}
+	// 返回浅拷贝以防止调用方修改缓存内部数据
+	copied := make([]model.Post, len(c.posts))
+	copy(copied, c.posts)
+	return copied, c.total, true
+}
+
+// Set 写入缓存数据
+func (c *HomePageCache) Set(posts []model.Post, total int64) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	// 深拷贝一份避免外部修改影响缓存
+	c.posts = make([]model.Post, len(posts))
+	copy(c.posts, posts)
+	c.total = total
+	c.expires = time.Now().Add(c.ttl)
+}
+
+// Invalidate 主动失效缓存
+func (c *HomePageCache) Invalidate() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.posts = nil
+	c.total = 0
+	c.expires = time.Time{}
+}

internal/router/deps_core.go

@@ -4,6 +4,7 @@ import (
 	"log"
 	"time"
 
+	"metazone.cc/metalab/internal/cache"
 	"metazone.cc/metalab/internal/config"
 	"metazone.cc/metalab/internal/controller"
 	adminCtrl "metazone.cc/metalab/internal/controller/admin"
@@ -42,6 +43,7 @@ type dependencies struct {
 	favoriteCtrl    *controller.FavoriteController
 	favoriteService *service.FavoriteService
 	trendsService   *service.TrendsService
+	homeCache       *cache.HomePageCache
 }
 
 func buildDepsCore(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings, redisClient *redis.Client) (

internal/router/deps_extra.go

@@ -1,6 +1,9 @@
 package router
 
 import (
+	"time"
+
+	"metazone.cc/metalab/internal/cache"
 	"metazone.cc/metalab/internal/config"
 	"metazone.cc/metalab/internal/controller"
 	adminCtrl "metazone.cc/metalab/internal/controller/admin"
@@ -99,6 +102,10 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 
 	maintenanceMdw := middleware.NewMaintenanceMiddleware(cfg, siteSettings, sessionMgr)
 
+	// 首页内存缓存（30s TTL），文章变更时失效
+	homeCache := cache.NewHomePageCache(30 * time.Second)
+	postService.WithHomePageInvalidator(func() { homeCache.Invalidate() })
+
 	return &dependencies{
 		authCtrl: authCtrl, authMdw: authMdw, maintenanceMdw: maintenanceMdw,
 		settingsCtrl: settingsCtrl,
@@ -119,5 +126,6 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 		favoriteCtrl:    favoriteCtrl,
 		favoriteService: favoriteService,
 		trendsService:   trendsService,
+		homeCache:       homeCache,
 	}
 }

internal/router/frontend.go

@@ -22,10 +22,16 @@ func setupFrontendRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 	})
 	{
 		pages.GET("/", func(c *gin.Context) {
-			posts, total, err := d.postService.List("", 1, 6)
+			posts, total, ok := d.homeCache.Get()
-			if err != nil {
+			if !ok {
-				posts = nil
+				var err error
-				total = 0
+				posts, total, err = d.postService.List("", 1, 6)
+				if err != nil {
+					posts = nil
+					total = 0
+				} else {
+					d.homeCache.Set(posts, total)
+				}
 			}
 			c.HTML(http.StatusOK, "home/index.html", common.BuildPageData(c, gin.H{
 				"Title":     "首页",

internal/service/post_audit_service.go

@@ -21,7 +21,11 @@ func (s *PostService) Update(postID uint, title, body string) error {
 		post.PendingTitle = title
 		post.PendingBody = body
 		post.RejectReason = "" // 清空旧退回理由
-		return s.repo.Update(post)
+		err := s.repo.Update(post)
+		if err == nil {
+			s.invalidateHomeCache()
+		}
+		return err
 	}
 
 	// 草稿/已退回：直接修改原文（现有逻辑）
@@ -34,12 +38,20 @@ func (s *PostService) Update(postID uint, title, body string) error {
 		post.RejectReason = ""
 	}
 
-	return s.repo.Update(post)
+	err = s.repo.Update(post)
+	if err == nil {
+		s.invalidateHomeCache()
+	}
+	return err
 }
 
 // Delete 软删除（权限在 controller 层检查）
 func (s *PostService) Delete(postID uint) error {
-	return s.repo.SoftDelete(postID)
+	if err := s.repo.SoftDelete(postID); err != nil {
+		return err
+	}
+	s.invalidateHomeCache()
+	return nil
 }
 
 // SubmitForAudit 提交审核：draft → pending
@@ -79,6 +91,7 @@ func (s *PostService) Approve(postID uint) error {
 		if err := s.repo.Update(post); err != nil {
 			return err
 		}
+		s.invalidateHomeCache()
 		// 通知作者修订审核通过
 		if s.notifier != nil {
 			s.notifier.NotifyPostApproved(post.UserID, post.Title, post.ID)
@@ -95,6 +108,7 @@ func (s *PostService) Approve(postID uint) error {
 	if err := s.repo.Update(post); err != nil {
 		return err
 	}
+	s.invalidateHomeCache()
 	// 通知作者审核通过
 	if s.notifier != nil {
 		s.notifier.NotifyPostApproved(post.UserID, post.Title, post.ID)

internal/service/post_service.go

@@ -13,10 +13,11 @@ import (
 
 // PostService 帖子业务逻辑
 type PostService struct {
-	repo     postStore
+	repo                postStore
-	ss       *config.SiteSettings
+	ss                  *config.SiteSettings
-	notifier postNotifier
+	notifier            postNotifier
-	userRepo userExpReader
+	userRepo            userExpReader
+	onHomePageChanged   func()
 }
 
 // NewPostService 构造函数
@@ -29,6 +30,11 @@ func NewPostService(repo postStore, ss *config.SiteSettings, notifier postNotifi
 	}
 }
 
+// WithHomePageInvalidator 注入首页缓存失效回调（文章变更时触发）
+func (s *PostService) WithHomePageInvalidator(fn func()) {
+	s.onHomePageChanged = fn
+}
+
 // auditEnabled 审核是否开启
 func (s *PostService) auditEnabled() bool {
 	return s.ss.IsAuditEnabled()
@@ -78,6 +84,7 @@ func (s *PostService) Create(userID uint, title, body string) (*model.Post, erro
 	if err := s.repo.Create(post); err != nil {
 		return nil, err
 	}
+	s.invalidateHomeCache()
 	return post, nil
 }
 
@@ -156,6 +163,13 @@ func (s *PostService) CanCreatePost(userID uint) bool {
 	return user.Exp >= 1
 }
 
+// invalidateHomeCache 失效首页缓存（异步安全调用）
+func (s *PostService) invalidateHomeCache() {
+	if s.onHomePageChanged != nil {
+		s.onHomePageChanged()
+	}
+}
+
 // RecordRead 记录已登录用户阅读文章（已登录去重 + 防刷冷却）
 func (s *PostService) RecordRead(userID, postID uint) {
 	firstRead, err := s.repo.RecordRead(userID, postID)