mirror of
https://github.com/putyy/res-downloader.git
synced 2026-01-12 14:14:55 +08:00
378 lines
9.3 KiB
Go
378 lines
9.3 KiB
Go
package core
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import (
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"errors"
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"fmt"
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"io"
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"net/http"
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"net/url"
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"os"
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"path/filepath"
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"strings"
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"sync"
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"time"
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)
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// 定义常量
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const (
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MaxRetries = 3 // 最大重试次数
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RetryDelay = 3 * time.Second // 重试延迟
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MinPartSize = 1 * 1024 * 1024 // 最小分片大小（1MB）
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)
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// 错误定义
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var (
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ErrInvalidFileSize = errors.New("invalid file size")
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ErrTaskFailed = errors.New("download task failed")
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ErrIncompleteDownload = errors.New("incomplete download")
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)
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// 进度回调函数
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type ProgressCallback func(totalDownloaded float64, totalSize float64, taskID int, taskProgress float64)
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// 进度通道
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type ProgressChan struct {
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taskID int
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bytes int64
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}
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// 下载任务
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type DownloadTask struct {
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taskID int
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rangeStart int64
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rangeEnd int64
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downloadedSize int64
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isCompleted bool
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err error
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}
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type FileDownloader struct {
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Url string
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Referer string
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ProxyUrl *url.URL
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FileName string
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File *os.File
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totalTasks int
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TotalSize int64
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IsMultiPart bool
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Headers map[string]string
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DownloadTaskList []*DownloadTask
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progressCallback ProgressCallback
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}
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func NewFileDownloader(url, filename string, totalTasks int, headers map[string]string) *FileDownloader {
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return &FileDownloader{
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Url: url,
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FileName: filename,
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totalTasks: totalTasks,
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IsMultiPart: false,
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TotalSize: 0,
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Headers: headers,
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DownloadTaskList: make([]*DownloadTask, 0),
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}
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}
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func (fd *FileDownloader) buildClient() *http.Client {
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transport := &http.Transport{
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MaxIdleConnsPerHost: 100,
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IdleConnTimeout: 90 * time.Second,
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}
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if fd.ProxyUrl != nil {
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transport.Proxy = http.ProxyURL(fd.ProxyUrl)
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}
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return &http.Client{
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Transport: transport,
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Timeout: 60 * time.Second,
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}
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}
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func (fd *FileDownloader) setHeaders(request *http.Request) {
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for key, value := range fd.Headers {
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if strings.Contains(globalConfig.UseHeaders, key) {
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request.Header.Set(key, value)
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}
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}
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}
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func (fd *FileDownloader) init() error {
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parsedURL, err := url.Parse(fd.Url)
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if err != nil {
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return fmt.Errorf("parse URL failed: %w", err)
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}
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if parsedURL.Scheme != "" && parsedURL.Host != "" {
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fd.Referer = parsedURL.Scheme + "://" + parsedURL.Host + "/"
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}
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if globalConfig.DownloadProxy && globalConfig.UpstreamProxy != "" && !strings.Contains(globalConfig.UpstreamProxy, globalConfig.Port) {
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proxyURL, err := url.Parse(globalConfig.UpstreamProxy)
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if err == nil {
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fd.ProxyUrl = proxyURL
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}
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}
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request, err := http.NewRequest("HEAD", fd.Url, nil)
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if err != nil {
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return fmt.Errorf("create HEAD request failed: %w", err)
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}
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if _, ok := fd.Headers["User-Agent"]; !ok {
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fd.Headers["User-Agent"] = globalConfig.UserAgent
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}
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if _, ok := fd.Headers["Referer"]; !ok {
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fd.Headers["Referer"] = fd.Referer
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}
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fd.setHeaders(request)
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var resp *http.Response
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for retries := 0; retries < MaxRetries; retries++ {
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resp, err = fd.buildClient().Do(request)
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if err == nil {
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break
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}
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if retries < MaxRetries-1 {
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time.Sleep(RetryDelay)
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globalLogger.Warn().Msgf("HEAD request failed, retrying (%d/%d): %v", retries+1, MaxRetries, err)
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}
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}
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if err != nil {
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return fmt.Errorf("HEAD request failed after %d retries: %w", MaxRetries, err)
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}
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defer resp.Body.Close()
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fd.TotalSize = resp.ContentLength
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if fd.TotalSize <= 0 {
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return ErrInvalidFileSize
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}
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if resp.Header.Get("Accept-Ranges") == "bytes" && fd.TotalSize > MinPartSize {
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fd.IsMultiPart = true
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}
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dir := filepath.Dir(fd.FileName)
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if err := os.MkdirAll(dir, os.ModePerm); err != nil {
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return fmt.Errorf("create directory failed: %w", err)
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}
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fd.File, err = os.OpenFile(fd.FileName, os.O_RDWR|os.O_CREATE, 0644)
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if err != nil {
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return fmt.Errorf("file open failed: %w", err)
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}
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if err := fd.File.Truncate(fd.TotalSize); err != nil {
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fd.File.Close()
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return fmt.Errorf("file truncate failed: %w", err)
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}
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return nil
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}
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func (fd *FileDownloader) createDownloadTasks() {
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if fd.IsMultiPart {
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if fd.totalTasks <= 0 {
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fd.totalTasks = 4
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}
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eachSize := fd.TotalSize / int64(fd.totalTasks)
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if eachSize < MinPartSize {
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fd.totalTasks = int(fd.TotalSize / MinPartSize)
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if fd.totalTasks < 1 {
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fd.totalTasks = 1
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}
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eachSize = fd.TotalSize / int64(fd.totalTasks)
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}
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for i := 0; i < fd.totalTasks; i++ {
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start := eachSize * int64(i)
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end := eachSize*int64(i+1) - 1
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if i == fd.totalTasks-1 {
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end = fd.TotalSize - 1
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}
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fd.DownloadTaskList = append(fd.DownloadTaskList, &DownloadTask{
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taskID: i,
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rangeStart: start,
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rangeEnd: end,
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})
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}
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} else {
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fd.totalTasks = 1
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fd.DownloadTaskList = append(fd.DownloadTaskList, &DownloadTask{
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taskID: 0,
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rangeStart: 0,
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rangeEnd: fd.TotalSize - 1,
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})
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}
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}
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func (fd *FileDownloader) startDownload() error {
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wg := &sync.WaitGroup{}
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progressChan := make(chan ProgressChan, len(fd.DownloadTaskList))
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errorChan := make(chan error, len(fd.DownloadTaskList))
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for _, task := range fd.DownloadTaskList {
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wg.Add(1)
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go fd.startDownloadTask(wg, progressChan, errorChan, task)
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}
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go func() {
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taskProgress := make([]int64, len(fd.DownloadTaskList))
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totalDownloaded := int64(0)
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for progress := range progressChan {
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taskProgress[progress.taskID] += progress.bytes
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totalDownloaded += progress.bytes
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if fd.progressCallback != nil {
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taskPercentage := float64(0)
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if task := fd.DownloadTaskList[progress.taskID]; task != nil {
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taskSize := task.rangeEnd - task.rangeStart + 1
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if taskSize > 0 {
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taskPercentage = float64(taskProgress[progress.taskID]) / float64(taskSize) * 100
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}
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}
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fd.progressCallback(float64(totalDownloaded), float64(fd.TotalSize), progress.taskID, taskPercentage)
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}
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}
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}()
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go func() {
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wg.Wait()
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close(progressChan)
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close(errorChan)
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}()
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var errArr []error
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for err := range errorChan {
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errArr = append(errArr, err)
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}
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if len(errArr) > 0 {
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return fmt.Errorf("download failed with %d errors: %v", len(errArr), errArr[0])
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}
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if err := fd.verifyDownload(); err != nil {
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return err
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}
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return nil
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}
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func (fd *FileDownloader) startDownloadTask(wg *sync.WaitGroup, progressChan chan ProgressChan, errorChan chan error, task *DownloadTask) {
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defer wg.Done()
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for retries := 0; retries < MaxRetries; retries++ {
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err := fd.doDownloadTask(progressChan, task)
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if err == nil {
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task.isCompleted = true
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return
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}
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task.err = err
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globalLogger.Warn().Msgf("Task %d failed (attempt %d/%d): %v", task.taskID, retries+1, MaxRetries, err)
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if retries < MaxRetries-1 {
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time.Sleep(RetryDelay)
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}
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}
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errorChan <- fmt.Errorf("task %d failed after %d attempts: %v", task.taskID, MaxRetries, task.err)
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}
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func (fd *FileDownloader) doDownloadTask(progressChan chan ProgressChan, task *DownloadTask) error {
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request, err := http.NewRequest("GET", fd.Url, nil)
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if err != nil {
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return fmt.Errorf("create request failed: %w", err)
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}
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fd.setHeaders(request)
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if fd.IsMultiPart {
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rangeStart := task.rangeStart + task.downloadedSize
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rangeHeader := fmt.Sprintf("bytes=%d-%d", rangeStart, task.rangeEnd)
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request.Header.Set("Range", rangeHeader)
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}
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client := fd.buildClient()
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resp, err := client.Do(request)
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if err != nil {
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return fmt.Errorf("send request failed: %w", err)
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}
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defer resp.Body.Close()
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if fd.IsMultiPart && resp.StatusCode != http.StatusPartialContent {
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return fmt.Errorf("server does not support range requests, status: %d", resp.StatusCode)
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} else if !fd.IsMultiPart && resp.StatusCode != http.StatusOK {
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return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
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}
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buf := make([]byte, 32*1024)
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for {
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n, err := resp.Body.Read(buf)
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if n > 0 {
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remain := task.rangeEnd - (task.rangeStart + task.downloadedSize) + 1
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writeSize := int64(n)
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if writeSize > remain {
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writeSize = remain
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}
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_, writeErr := fd.File.WriteAt(buf[:writeSize], task.rangeStart+task.downloadedSize)
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if writeErr != nil {
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return fmt.Errorf("write file failed at offset %d: %w", task.rangeStart+task.downloadedSize, writeErr)
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}
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task.downloadedSize += writeSize
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progressChan <- ProgressChan{taskID: task.taskID, bytes: writeSize}
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if task.rangeStart+task.downloadedSize-1 >= task.rangeEnd {
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return nil
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}
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}
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if err != nil {
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if err == io.EOF {
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expectedSize := task.rangeEnd - task.rangeStart + 1
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if task.downloadedSize < expectedSize {
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return fmt.Errorf("incomplete download: got %d bytes, expected %d", task.downloadedSize, expectedSize)
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}
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return nil
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}
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return fmt.Errorf("read response failed: %w", err)
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}
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}
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}
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func (fd *FileDownloader) verifyDownload() error {
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for _, task := range fd.DownloadTaskList {
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if !task.isCompleted {
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return fmt.Errorf("task %d not completed", task.taskID)
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}
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expectedSize := task.rangeEnd - task.rangeStart + 1
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if task.downloadedSize != expectedSize {
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return fmt.Errorf("task %d size mismatch: got %d, expected %d", task.taskID, task.downloadedSize, expectedSize)
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}
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}
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info, err := fd.File.Stat()
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if err != nil {
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return fmt.Errorf("get file info failed: %w", err)
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}
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if info.Size() != fd.TotalSize {
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return fmt.Errorf("file size mismatch: got %d, expected %d", info.Size(), fd.TotalSize)
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}
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return nil
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}
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func (fd *FileDownloader) Start() error {
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if err := fd.init(); err != nil {
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return err
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}
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fd.createDownloadTasks()
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err := fd.startDownload()
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if fd.File != nil {
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fd.File.Close()
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}
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return err
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}
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