From 3b2360162cfa774c4724246aefcbc606586dc6c6 Mon Sep 17 00:00:00 2001
From: xfy <i@rua.plus>
Date: Fri, 8 May 2026 18:06:13 +0800
Subject: [PATCH] refactor(utils): add unified ETag generation function

Extract duplicate generateETag function from handler/static.go and
cache/file_cache.go into internal/utils/etag.go. Both functions were
identical, using strconv.AppendInt for zero-allocation ETag generation.

- Create utils.GenerateETag(modTime, size) as the unified implementation
- Update handler/static.go to call utils.GenerateETag
- Update cache/file_cache.go to call utils.GenerateETag
- Remove unused strconv import from static.go

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 internal/cache/file_cache.go | 12 +++---------
 internal/handler/static.go   | 10 +---------
 internal/utils/etag.go       | 20 ++++++++++++++++++++
 3 files changed, 24 insertions(+), 18 deletions(-)
 create mode 100644 internal/utils/etag.go

diff --git a/internal/cache/file_cache.go b/internal/cache/file_cache.go
index 1494b5f..2e954eb 100644
--- a/internal/cache/file_cache.go
+++ b/internal/cache/file_cache.go
@@ -20,11 +20,12 @@ package cache
 import (
 	"container/list"
 	"slices"
-	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
+
+	"rua.plus/lolly/internal/utils"
 )
 
 // FileEntry 文件缓存条目，存储单个文件的缓存信息。
@@ -43,14 +44,7 @@ type FileEntry struct {
 // generateETag 基于 ModTime 和 Size 生成 ETag。
 // 使用 strconv.AppendInt 避免 fmt.Sprintf 分配。
 func generateETag(modTime time.Time, size int64) string {
-	var buf [32]byte
-	b := buf[:0]
-	b = append(b, '"')
-	b = strconv.AppendInt(b, modTime.Unix(), 16)
-	b = append(b, '-')
-	b = strconv.AppendInt(b, size, 16)
-	b = append(b, '"')
-	return string(b)
+	return utils.GenerateETag(modTime, size)
 }
 
 // FileCache 文件缓存，支持 LRU 淘汰策略。
diff --git a/internal/handler/static.go b/internal/handler/static.go
index 2b5ce90..e8810f0 100644
--- a/internal/handler/static.go
+++ b/internal/handler/static.go
@@ -22,7 +22,6 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"strconv"
 	"strings"
 	"time"
 
@@ -913,14 +912,7 @@ func (h *StaticHandler) validateSymlink(filePath string) error {
 // generateETag 基于 ModTime 和 Size 生成 ETag。
 // 使用 strconv.AppendInt 避免 fmt.Sprintf 分配。
 func generateETag(modTime time.Time, size int64) string {
-	var buf [32]byte
-	b := buf[:0]
-	b = append(b, '"')
-	b = strconv.AppendInt(b, modTime.Unix(), 16)
-	b = append(b, '-')
-	b = strconv.AppendInt(b, size, 16)
-	b = append(b, '"')
-	return string(b)
+	return utils.GenerateETag(modTime, size)
 }
 
 // isNotModified 检查条件请求是否匹配（返回 true 表示应返回 304）。
diff --git a/internal/utils/etag.go b/internal/utils/etag.go
new file mode 100644
index 0000000..3385b15
--- /dev/null
+++ b/internal/utils/etag.go
@@ -0,0 +1,20 @@
+package utils
+
+import (
+	"strconv"
+	"time"
+)
+
+// GenerateETag 基于 ModTime 和 Size 生成 ETag。
+// 使用 strconv.AppendInt 避免 fmt.Sprintf 分配。
+// 格式: "<modtime-unix-hex>-<size-hex>"
+func GenerateETag(modTime time.Time, size int64) string {
+	var buf [32]byte
+	b := buf[:0]
+	b = append(b, '"')
+	b = strconv.AppendInt(b, modTime.Unix(), 16)
+	b = append(b, '-')
+	b = strconv.AppendInt(b, size, 16)
+	b = append(b, '"')
+	return string(b)
+}