新增: SFTP直连+网站预览+OSS区域嗅探+热键+BGM播放
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187
internal/storage/download_cache.go
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187
internal/storage/download_cache.go
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package storage
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import (
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"crypto/sha256"
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"fmt"
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"os"
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"path/filepath"
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"time"
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"u-desk/internal/storage/models"
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"gorm.io/gorm"
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)
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const downloadCacheTTL = 24 * time.Hour
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// cacheTempDir 确定性临时目录
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var cacheTempDir = filepath.Join(os.TempDir(), "u-desk-cache")
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// GetCachedPath 查询缓存，验证文件存在后返回本地路径
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func GetCachedPath(transport, connID, remotePath string, fileSize int64, modTime string) (string, bool) {
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db := GetDB()
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if db == nil {
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return "", false
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}
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var entry models.DownloadCache
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err := db.Where("transport = ? AND conn_id = ? AND remote_path = ? AND file_size = ? AND mod_time = ?",
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transport, connID, remotePath, fileSize, modTime).First(&entry).Error
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if err != nil {
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return "", false
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}
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// 检查文件是否仍然存在于磁盘
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if _, err := os.Stat(entry.LocalPath); err != nil {
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// 文件已丢失，清理过期记录
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db.Delete(&entry)
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return "", false
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}
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// 检查是否过期
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if time.Since(entry.DownloadedAt) > downloadCacheTTL {
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os.Remove(entry.LocalPath)
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db.Delete(&entry)
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return "", false
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}
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return entry.LocalPath, true
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}
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// SaveCache 保存或更新缓存记录
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func SaveCache(transport, connID, remotePath string, fileSize int64, modTime, localPath string) {
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db := GetDB()
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if db == nil {
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return
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}
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var existing models.DownloadCache
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err := db.Where("transport = ? AND conn_id = ? AND remote_path = ? AND file_size = ? AND mod_time = ?",
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transport, connID, remotePath, fileSize, modTime).First(&existing).Error
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if err == gorm.ErrRecordNotFound {
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db.Create(&models.DownloadCache{
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Transport: transport,
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ConnID: connID,
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RemotePath: remotePath,
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FileSize: fileSize,
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ModTime: modTime,
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LocalPath: localPath,
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DownloadedAt: time.Now(),
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})
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} else if err == nil {
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db.Model(&existing).Updates(map[string]any{
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"local_path": localPath,
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"downloaded_at": time.Now(),
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})
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}
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}
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// CleanupExpiredCache 清理超过 24h 的缓存记录并删除对应临时文件
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func CleanupExpiredCache() {
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db := GetDB()
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if db == nil {
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return
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}
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cutoff := time.Now().Add(-downloadCacheTTL)
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var expired []models.DownloadCache
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db.Where("downloaded_at < ?", cutoff).Find(&expired)
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for _, entry := range expired {
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os.Remove(entry.LocalPath)
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db.Delete(&entry)
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}
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if len(expired) > 0 {
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fmt.Printf("[下载缓存] 清理 %d 条过期记录\n", len(expired))
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}
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}
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// DownloadToTempCached 带缓存的下载：命中返回本地路径，未命中调用 downloadFn 后缓存结果
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func DownloadToTempCached(transport, connID, remotePath string, fileSize int64, modTime string, downloadFn func() (string, error)) (string, error) {
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// 1. 查缓存
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if localPath, hit := GetCachedPath(transport, connID, remotePath, fileSize, modTime); hit {
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return localPath, nil
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}
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// 2. 缓存未命中，执行下载
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tempPath, err := downloadFn()
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if err != nil {
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return "", err
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}
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// 3. 生成确定性路径并移动文件
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deterministicPath, err := deterministicCachePath(transport, connID, remotePath, fileSize, modTime)
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if err != nil {
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// 降级：直接使用 downloadFn 返回的路径，仍然缓存
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SaveCache(transport, connID, remotePath, fileSize, modTime, tempPath)
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return tempPath, nil
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}
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// 确保目录存在
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if err := os.MkdirAll(filepath.Dir(deterministicPath), 0755); err != nil {
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SaveCache(transport, connID, remotePath, fileSize, modTime, tempPath)
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return tempPath, nil
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}
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// 移动文件到确定性路径
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if err := os.Rename(tempPath, deterministicPath); err != nil {
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// Rename 可能跨卷失败，尝试 Copy+Delete
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if copyFile(tempPath, deterministicPath) != nil {
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SaveCache(transport, connID, remotePath, fileSize, modTime, tempPath)
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return tempPath, nil
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}
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os.Remove(tempPath)
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}
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SaveCache(transport, connID, remotePath, fileSize, modTime, deterministicPath)
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return deterministicPath, nil
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}
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// deterministicCachePath 根据文件信息生成确定性的缓存路径
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func deterministicCachePath(transport, connID, remotePath string, fileSize int64, modTime string) (string, error) {
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h := sha256.New()
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h.Write([]byte(fmt.Sprintf("%s:%s:%s:%d:%s", transport, connID, remotePath, fileSize, modTime)))
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hash := fmt.Sprintf("%x", h.Sum(nil))[:16]
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baseName := filepath.Base(remotePath)
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if baseName == "" || baseName == "." || baseName == "/" {
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baseName = "file"
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}
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// 截断过长的文件名
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if len(baseName) > 64 {
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ext := filepath.Ext(baseName)
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maxName := 64 - len(ext)
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if maxName <= 0 {
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maxName = 1
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ext = ext[:63]
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}
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baseName = baseName[:maxName] + ext
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}
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fileName := fmt.Sprintf("%s_%s", hash, baseName)
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return filepath.Join(cacheTempDir, fileName), nil
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}
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// copyFile 复制文件内容
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func copyFile(src, dst string) error {
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in, err := os.Open(src)
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if err != nil {
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return err
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}
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defer in.Close()
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out, err := os.Create(dst)
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if err != nil {
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return err
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}
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defer out.Close()
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if _, err := out.ReadFrom(in); err != nil {
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os.Remove(dst)
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return err
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}
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return nil
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}
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