feat(cache): store ContentType in FileEntry for cache hits

- Add ContentType field to FileEntry struct
- Update Set method signature to accept contentType parameter
- Use cached ContentType in static.go cache hit branches
- Update all test files to use new Set signature

This avoids redundant MIME type detection on cache hits,
reducing lock contention in mimeutil.DetectContentType.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/cache/cache_bench_test.go

@@ -35,7 +35,7 @@ func BenchmarkFileCacheGet(b *testing.B) {
 			for i := range size {
 				path := fmt.Sprintf("/file%d.txt", i)
 				data := []byte("cached data content")
-				_ = fc.Set(path, data, int64(len(data)), time.Now())
+				_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 			}
 
 			b.ResetTimer()
@@ -65,14 +65,14 @@ func BenchmarkFileCacheSet(b *testing.B) {
 			for i := range size {
 				path := fmt.Sprintf("/file%d.txt", i)
 				data := []byte("cached data content")
-				_ = fc.Set(path, data, int64(len(data)), time.Now())
+				_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 			}
 
 			b.ResetTimer()
 			for i := 0; b.Loop(); i++ {
 				path := fmt.Sprintf("/newfile%d.txt", i)
 				data := []byte("new cached data content")
-				_ = fc.Set(path, data, int64(len(data)), time.Now())
+				_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 			}
 		})
 	}
@@ -91,7 +91,7 @@ func BenchmarkFileCacheSet_Pooled(b *testing.B) {
 			for i := range size {
 				path := fmt.Sprintf("/file%d.txt", i)
 				data := []byte("cached data content")
-				_ = fc.Set(path, data, int64(len(data)), time.Now())
+				_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 			}
 
 			b.ReportAllocs()
@@ -99,7 +99,7 @@ func BenchmarkFileCacheSet_Pooled(b *testing.B) {
 			for i := 0; b.Loop(); i++ {
 				path := fmt.Sprintf("/newfile%d.txt", i)
 				data := []byte("new cached data content")
-				_ = fc.Set(path, data, int64(len(data)), time.Now())
+				_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 			}
 		})
 	}
@@ -114,7 +114,7 @@ func BenchmarkFileCacheSetNoEviction(b *testing.B) {
 	for i := 0; b.Loop(); i++ {
 		path := fmt.Sprintf("/file%d.txt", i)
 		data := []byte("cached data content")
-		_ = fc.Set(path, data, int64(len(data)), time.Now())
+		_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 	}
 }
 
@@ -131,7 +131,7 @@ func BenchmarkFileCacheConcurrent(b *testing.B) {
 			for i := range size {
 				path := fmt.Sprintf("/file%d.txt", i)
 				data := []byte("cached data content")
-				_ = fc.Set(path, data, int64(len(data)), time.Now())
+				_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 			}
 
 			b.ResetTimer()
@@ -142,7 +142,7 @@ func BenchmarkFileCacheConcurrent(b *testing.B) {
 					if i%10 == 0 {
 						path := fmt.Sprintf("/newfile%d.txt", i)
 						data := []byte("updated data content")
-						_ = fc.Set(path, data, int64(len(data)), time.Now())
+						_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 					} else {
 						path := fmt.Sprintf("/file%d.txt", i%size)
 						fc.Get(path)
@@ -163,7 +163,7 @@ func BenchmarkFileCacheGetOnly(b *testing.B) {
 	for i := range 1000 {
 		path := fmt.Sprintf("/static/file%d.css", i)
 		data := make([]byte, 1024) // 1KB 数据
-		_ = fc.Set(path, data, int64(len(data)), time.Now())
+		_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 	}
 
 	b.ResetTimer()
@@ -188,14 +188,14 @@ func BenchmarkFileCacheSizeEviction(b *testing.B) {
 	data := make([]byte, 1024) // 1KB 每条
 	for i := range 1000 {
 		path := fmt.Sprintf("/file%d.txt", i)
-		_ = fc.Set(path, data, int64(len(data)), time.Now())
+		_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 	}
 
 	b.ResetTimer()
 	for i := 0; b.Loop(); i++ {
 		path := fmt.Sprintf("/newfile%d.txt", i)
 		newData := make([]byte, 1024)
-		_ = fc.Set(path, newData, int64(len(newData)), time.Now())
+		_ = fc.Set(path, newData, int64(len(newData)), time.Now(), "text/plain")
 	}
 }
 
@@ -208,7 +208,7 @@ func BenchmarkFileCacheLRUTouch(b *testing.B) {
 	for i := range 100 {
 		path := fmt.Sprintf("/file%d.txt", i)
 		data := []byte("cached data")
-		_ = fc.Set(path, data, int64(len(data)), time.Now())
+		_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 	}
 
 	b.ResetTimer()

internal/cache/cache_test.go

@@ -36,7 +36,7 @@ func TestFileCacheSetGet(t *testing.T) {
 	path := "/test/file.txt"
 	data := []byte("Hello, World!")
 
-	err := fc.Set(path, data, int64(len(data)), time.Now())
+	err := fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 	if err != nil {
 		t.Errorf("Set() error: %v", err)
 	}
@@ -53,7 +53,7 @@ func TestFileCacheSetGet(t *testing.T) {
 func TestFileCacheDelete(t *testing.T) {
 	fc := NewFileCache(10, 1024, 1*time.Hour)
 
-	_ = fc.Set("/test.txt", []byte("data"), 4, time.Now())
+	_ = fc.Set("/test.txt", []byte("data"), 4, time.Now(), "text/plain")
 
 	fc.Delete("/test.txt")
 
@@ -67,12 +67,12 @@ func TestFileCacheLRUEviction(t *testing.T) {
 	// 最大 3 个条目
 	fc := NewFileCache(3, 0, 1*time.Hour)
 
-	_ = fc.Set("/a", []byte("a"), 1, time.Now())
+	_ = fc.Set("/a", []byte("a"), 1, time.Now(), "text/plain")
-	_ = fc.Set("/b", []byte("b"), 1, time.Now())
+	_ = fc.Set("/b", []byte("b"), 1, time.Now(), "text/plain")
-	_ = fc.Set("/c", []byte("c"), 1, time.Now())
+	_ = fc.Set("/c", []byte("c"), 1, time.Now(), "text/plain")
 
 	// 再添加一个，应该淘汰 /a
-	_ = fc.Set("/d", []byte("d"), 1, time.Now())
+	_ = fc.Set("/d", []byte("d"), 1, time.Now(), "text/plain")
 
 	_, ok := fc.Get("/a")
 	if ok {
@@ -216,11 +216,11 @@ func TestFileCacheSizeEviction(t *testing.T) {
 	// 最大 10 字节
 	fc := NewFileCache(0, 10, 1*time.Hour)
 
-	_ = fc.Set("/a", []byte("12345"), 5, time.Now())
+	_ = fc.Set("/a", []byte("12345"), 5, time.Now(), "text/plain")
-	_ = fc.Set("/b", []byte("12345"), 5, time.Now())
+	_ = fc.Set("/b", []byte("12345"), 5, time.Now(), "text/plain")
 
 	// 再添加 6 字节，应该淘汰一个
-	_ = fc.Set("/c", []byte("123456"), 6, time.Now())
+	_ = fc.Set("/c", []byte("123456"), 6, time.Now(), "text/plain")
 
 	stats := fc.Stats()
 	if stats.Size > 10 {
@@ -231,7 +231,7 @@ func TestFileCacheSizeEviction(t *testing.T) {
 func TestFileCacheInactiveEviction(t *testing.T) {
 	fc := NewFileCache(10, 1024, 100*time.Millisecond)
 
-	_ = fc.Set("/test", []byte("data"), 4, time.Now())
+	_ = fc.Set("/test", []byte("data"), 4, time.Now(), "text/plain")
 
 	// 立即获取应该成功
 	_, ok := fc.Get("/test")
@@ -252,8 +252,8 @@ func TestFileCacheInactiveEviction(t *testing.T) {
 func TestFileCacheClear(t *testing.T) {
 	fc := NewFileCache(10, 1024, 1*time.Hour)
 
-	_ = fc.Set("/a", []byte("a"), 1, time.Now())
+	_ = fc.Set("/a", []byte("a"), 1, time.Now(), "text/plain")
-	_ = fc.Set("/b", []byte("b"), 1, time.Now())
+	_ = fc.Set("/b", []byte("b"), 1, time.Now(), "text/plain")
 
 	fc.Clear()
 
@@ -266,8 +266,8 @@ func TestFileCacheClear(t *testing.T) {
 func TestFileCacheStats(t *testing.T) {
 	fc := NewFileCache(100, 1024, 1*time.Hour)
 
-	_ = fc.Set("/a", []byte("12345"), 5, time.Now())
+	_ = fc.Set("/a", []byte("12345"), 5, time.Now(), "text/plain")
-	_ = fc.Set("/b", []byte("12345"), 5, time.Now())
+	_ = fc.Set("/b", []byte("12345"), 5, time.Now(), "text/plain")
 
 	stats := fc.Stats()
 	if stats.Entries != 2 {
@@ -569,7 +569,7 @@ func TestFileCacheRefreshCachedAt(t *testing.T) {
 	data := []byte("test data")
 
 	// 设置缓存
-	_ = fc.Set(path, data, int64(len(data)), time.Now())
+	_ = fc.Set(path, data, int64(len(data)), time.Now(), "text/plain")
 
 	// 获取原始 CachedAt 时间
 	entry, ok := fc.Get(path)

internal/cache/file_cache.go

@@ -29,14 +29,15 @@ import (
 
 // FileEntry 文件缓存条目，存储单个文件的缓存信息。
 type FileEntry struct {
-	ModTime    time.Time
+	ModTime     time.Time
-	CachedAt   time.Time // 缓存时间，用于 TTL 验证（新鲜度）
+	CachedAt    time.Time // 缓存时间，用于 TTL 验证（新鲜度）
-	LastAccess time.Time
+	LastAccess  time.Time
-	element    *list.Element
+	element     *list.Element
-	Path       string
+	Path        string
-	Data       []byte
+	Data        []byte
-	Size       int64
+	Size        int64
-	ETag       string // 预计算的 ETag，避免每次请求重新计算
+	ETag        string // 预计算的 ETag，避免每次请求重新计算
+	ContentType string // 预计算的 MIME 类型，避免每次请求重新检测
 }
 
 // generateETag 基于 ModTime 和 Size 生成 ETag。
@@ -173,10 +174,11 @@ func (c *FileCache) Get(path string) (*FileEntry, bool) {
 //   - data: 文件内容字节
 //   - size: 文件大小（字节）
 //   - modTime: 文件最后修改时间
+//   - contentType: MIME 类型
 //
 // 返回值：
 //   - error: 当前实现始终返回 nil
-func (c *FileCache) Set(path string, data []byte, size int64, modTime time.Time) error {
+func (c *FileCache) Set(path string, data []byte, size int64, modTime time.Time, contentType string) error {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -190,6 +192,7 @@ func (c *FileCache) Set(path string, data []byte, size int64, modTime time.Time)
 		entry.Size = size
 		entry.ModTime = modTime
 		entry.ETag = etag
+		entry.ContentType = contentType
 		entry.CachedAt = time.Now() // 更新缓存时间
 		entry.LastAccess = time.Now()
 		c.currentSize += size
@@ -205,6 +208,7 @@ func (c *FileCache) Set(path string, data []byte, size int64, modTime time.Time)
 	entry.Size = size
 	entry.ModTime = modTime
 	entry.ETag = etag
+	entry.ContentType = contentType
 	entry.CachedAt = time.Now()
 	entry.LastAccess = time.Now()
 	entry.element = c.lruList.PushFront(entry)
@@ -266,6 +270,7 @@ func (c *FileCache) removeEntry(entry *FileEntry) {
 	entry.CachedAt = time.Time{}
 	entry.LastAccess = time.Time{}
 	entry.ETag = ""
+	entry.ContentType = ""
 	entry.element = nil
 	c.entryPool.Put(entry)
 }

internal/cache/file_cache_allocation_test.go

@@ -37,7 +37,7 @@ func BenchmarkFileCacheSetAllocation_New(b *testing.B) {
 
 	for i := 0; b.Loop(); i++ {
 		path := fmt.Sprintf("/new/file%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 }
 
@@ -52,7 +52,7 @@ func BenchmarkFileCacheSetAllocation_Update(b *testing.B) {
 	size := int64(len(data))
 	for i := range 1000 {
 		path := fmt.Sprintf("/update/file%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 
 	b.ReportAllocs()
@@ -61,7 +61,7 @@ func BenchmarkFileCacheSetAllocation_Update(b *testing.B) {
 	for i := 0; b.Loop(); i++ {
 		// 循环更新已有条目
 		path := fmt.Sprintf("/update/file%d.txt", i%1000)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 }
 
@@ -80,7 +80,7 @@ func BenchmarkFileCacheSetAllocation_Eviction(b *testing.B) {
 	size := int64(len(data))
 	for i := range 100 {
 		path := fmt.Sprintf("/evict/file%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 
 	b.ReportAllocs()
@@ -89,7 +89,7 @@ func BenchmarkFileCacheSetAllocation_Eviction(b *testing.B) {
 	for i := 0; b.Loop(); i++ {
 		// 每个 Set 都触发淘汰
 		path := fmt.Sprintf("/evict/new%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 }
 
@@ -105,7 +105,7 @@ func BenchmarkFileCacheSetAllocation_EvictionWithPool(b *testing.B) {
 	// 预填充
 	for i := range 100 {
 		path := fmt.Sprintf("/pool/file%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 
 	b.ReportAllocs()
@@ -113,7 +113,7 @@ func BenchmarkFileCacheSetAllocation_EvictionWithPool(b *testing.B) {
 
 	for i := 0; b.Loop(); i++ {
 		path := fmt.Sprintf("/pool/new%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 }
 
@@ -130,7 +130,7 @@ func BenchmarkFileCacheSetAllocation_MemoryLimit(b *testing.B) {
 	// 预填充到接近上限
 	for i := range 900 {
 		path := fmt.Sprintf("/mem/file%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 
 	b.ReportAllocs()
@@ -138,7 +138,7 @@ func BenchmarkFileCacheSetAllocation_MemoryLimit(b *testing.B) {
 
 	for i := 0; b.Loop(); i++ {
 		path := fmt.Sprintf("/mem/new%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 }
 
@@ -158,7 +158,7 @@ func BenchmarkFileCacheSetAllocation_Concurrent(b *testing.B) {
 		i := 0
 		for pb.Next() {
 			path := fmt.Sprintf("/conc/file%d.txt", i)
-			fc.Set(path, data, size, time.Now())
+			fc.Set(path, data, size, time.Now(), "text/plain")
 			i++
 		}
 	})
@@ -174,7 +174,7 @@ func BenchmarkFileCacheSetAllocation_ConcurrentEviction(b *testing.B) {
 	// 预填充
 	for i := range 100 {
 		path := fmt.Sprintf("/concevict/file%d.txt", i)
-		fc.Set(path, data, size, time.Now())
+		fc.Set(path, data, size, time.Now(), "text/plain")
 	}
 
 	b.ReportAllocs()
@@ -184,7 +184,7 @@ func BenchmarkFileCacheSetAllocation_ConcurrentEviction(b *testing.B) {
 		i := 0
 		for pb.Next() {
 			path := fmt.Sprintf("/concevict/new%d.txt", i)
-			fc.Set(path, data, size, time.Now())
+			fc.Set(path, data, size, time.Now(), "text/plain")
 			i++
 		}
 	})

internal/handler/static.go

@@ -660,7 +660,7 @@ func (h *StaticHandler) handleStandard(ctx *fasthttp.RequestCtx, reqPath string)
 					return
 				}
 				ctx.Response.SetBody(entry.Data)
-				ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
+				ctx.Response.Header.SetContentType(entry.ContentType)
 				ctx.Response.Header.Set("ETag", entry.ETag)
 				ctx.Response.Header.Set("Last-Modified", info.ModTime().UTC().Format(httpTimeFormat))
 				return
@@ -681,7 +681,7 @@ func (h *StaticHandler) handleStandard(ctx *fasthttp.RequestCtx, reqPath string)
 					h.fileCache.RefreshCachedAt(filePath)
 				}
 				ctx.Response.SetBody(entry.Data)
-				ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
+				ctx.Response.Header.SetContentType(entry.ContentType)
 				ctx.Response.Header.Set("ETag", entry.ETag)
 				ctx.Response.Header.Set("Last-Modified", info.ModTime().UTC().Format(httpTimeFormat))
 				return
@@ -734,9 +734,9 @@ func (h *StaticHandler) serveFile(ctx *fasthttp.RequestCtx, filePath string, inf
 			// 检查文件是否被修改
 			if entry.ModTime.Equal(info.ModTime()) {
 				// 缓存命中且文件未修改
-				// 使用缓存的 ETag，避免重新生成
+				// 使用缓存的 ETag 和 ContentType，避免重新生成
 				ctx.Response.SetBody(entry.Data)
-				ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
+				ctx.Response.Header.SetContentType(entry.ContentType)
 				ctx.Response.Header.Set("ETag", entry.ETag)
 				ctx.Response.Header.Set("Last-Modified", info.ModTime().UTC().Format(httpTimeFormat))
 				h.setCacheHeaders(ctx)
@@ -776,12 +776,13 @@ func (h *StaticHandler) serveFile(ctx *fasthttp.RequestCtx, filePath string, inf
 	}
 
 	// 存入缓存（仅对小文件缓存）
+	contentType := mimeutil.DetectContentType(filePath)
 	if h.fileCache != nil && info.Size() < 1024*1024 { // < 1MB
-		_ = h.fileCache.Set(filePath, data, info.Size(), info.ModTime())
+		_ = h.fileCache.Set(filePath, data, info.Size(), info.ModTime(), contentType)
 	}
 
 	ctx.Response.SetBody(data)
-	ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
+	ctx.Response.Header.SetContentType(contentType)
 	ctx.Response.Header.Set("ETag", etag)
 	ctx.Response.Header.Set("Last-Modified", info.ModTime().UTC().Format(httpTimeFormat))
 	h.setCacheHeaders(ctx)