552 lines
13 KiB
Go
552 lines
13 KiB
Go
package oss
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import (
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"crypto/md5"
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"encoding/base64"
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"encoding/json"
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"errors"
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"hash"
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"hash/crc64"
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"io"
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"io/ioutil"
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"os"
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"strconv"
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)
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//
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// DownloadFile 分片下载文件
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//
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// objectKey object key。
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// filePath 本地文件。objectKey下载到文件。
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// partSize 本次上传文件片的大小，字节数。比如100 * 1024为每片100KB。
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// options Object的属性限制项。详见GetObject。
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//
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// error 操作成功error为nil，非nil为错误信息。
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//
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func (bucket Bucket) DownloadFile(objectKey, filePath string, partSize int64, options ...Option) error {
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if partSize < 1 {
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return errors.New("oss: part size smaller than 1")
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}
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cpConf, err := getCpConfig(options, filePath)
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if err != nil {
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return err
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}
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uRange, err := getRangeConfig(options)
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if err != nil {
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return err
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}
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routines := getRoutines(options)
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if cpConf.IsEnable {
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return bucket.downloadFileWithCp(objectKey, filePath, partSize, options, cpConf.FilePath, routines, uRange)
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}
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return bucket.downloadFile(objectKey, filePath, partSize, options, routines, uRange)
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}
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// 获取下载范围
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func getRangeConfig(options []Option) (*unpackedRange, error) {
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rangeOpt, err := findOption(options, HTTPHeaderRange, nil)
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if err != nil || rangeOpt == nil {
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return nil, err
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}
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return parseRange(rangeOpt.(string))
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}
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// ----- 并发无断点的下载 -----
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// 工作协程参数
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type downloadWorkerArg struct {
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bucket *Bucket
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key string
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filePath string
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options []Option
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hook downloadPartHook
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enableCRC bool
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}
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// Hook用于测试
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type downloadPartHook func(part downloadPart) error
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var downloadPartHooker downloadPartHook = defaultDownloadPartHook
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func defaultDownloadPartHook(part downloadPart) error {
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return nil
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}
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// 默认ProgressListener，屏蔽GetObject的Options中ProgressListener
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type defaultDownloadProgressListener struct {
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}
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// ProgressChanged 静默处理
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func (listener *defaultDownloadProgressListener) ProgressChanged(event *ProgressEvent) {
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}
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// 工作协程
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func downloadWorker(id int, arg downloadWorkerArg, jobs <-chan downloadPart, results chan<- downloadPart, failed chan<- error, die <-chan bool) {
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for part := range jobs {
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if err := arg.hook(part); err != nil {
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failed <- err
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break
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}
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// resolve options
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r := Range(part.Start, part.End)
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p := Progress(&defaultDownloadProgressListener{})
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opts := make([]Option, len(arg.options)+2)
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// append orderly, can not be reversed!
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opts = append(opts, arg.options...)
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opts = append(opts, r, p)
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rd, err := arg.bucket.GetObject(arg.key, opts...)
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if err != nil {
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failed <- err
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break
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}
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defer rd.Close()
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var crcCalc hash.Hash64
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if arg.enableCRC {
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crcCalc = crc64.New(crcTable())
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contentLen := part.End - part.Start + 1
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rd = ioutil.NopCloser(TeeReader(rd, crcCalc, contentLen, nil, nil))
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}
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defer rd.Close()
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select {
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case <-die:
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return
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default:
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}
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fd, err := os.OpenFile(arg.filePath, os.O_WRONLY, FilePermMode)
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if err != nil {
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failed <- err
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break
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}
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_, err = fd.Seek(part.Start-part.Offset, os.SEEK_SET)
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if err != nil {
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fd.Close()
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failed <- err
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break
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}
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_, err = io.Copy(fd, rd)
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if err != nil {
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fd.Close()
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failed <- err
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break
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}
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if arg.enableCRC {
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part.CRC64 = crcCalc.Sum64()
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}
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fd.Close()
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results <- part
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}
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}
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// 调度协程
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func downloadScheduler(jobs chan downloadPart, parts []downloadPart) {
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for _, part := range parts {
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jobs <- part
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}
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close(jobs)
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}
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// 下载片
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type downloadPart struct {
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Index int // 片序号，从0开始编号
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Start int64 // 片起始位置
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End int64 // 片结束位置
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Offset int64 // 文件中的偏移位置
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CRC64 uint64 // 片的校验值
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}
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// 文件分片
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func getDownloadParts(bucket *Bucket, objectKey string, partSize int64, uRange *unpackedRange) ([]downloadPart, bool, uint64, error) {
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meta, err := bucket.GetObjectDetailedMeta(objectKey)
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if err != nil {
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return nil, false, 0, err
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}
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parts := []downloadPart{}
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objectSize, err := strconv.ParseInt(meta.Get(HTTPHeaderContentLength), 10, 0)
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if err != nil {
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return nil, false, 0, err
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}
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enableCRC := false
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crcVal := (uint64)(0)
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if bucket.getConfig().IsEnableCRC && meta.Get(HTTPHeaderOssCRC64) != "" {
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if uRange == nil || (!uRange.hasStart && !uRange.hasEnd) {
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enableCRC = true
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crcVal, _ = strconv.ParseUint(meta.Get(HTTPHeaderOssCRC64), 10, 0)
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}
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}
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part := downloadPart{}
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i := 0
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start, end := adjustRange(uRange, objectSize)
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for offset := start; offset < end; offset += partSize {
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part.Index = i
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part.Start = offset
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part.End = GetPartEnd(offset, end, partSize)
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part.Offset = start
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part.CRC64 = 0
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parts = append(parts, part)
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i++
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}
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return parts, enableCRC, crcVal, nil
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}
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// 文件大小
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func getObjectBytes(parts []downloadPart) int64 {
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var ob int64
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for _, part := range parts {
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ob += (part.End - part.Start + 1)
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}
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return ob
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}
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// 计算连续分片总的CRC
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func combineCRCInParts(dps []downloadPart) uint64 {
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if dps == nil || len(dps) == 0 {
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return 0
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}
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crc := dps[0].CRC64
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for i := 1; i < len(dps); i++ {
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crc = CRC64Combine(crc, dps[i].CRC64, (uint64)(dps[i].End-dps[i].Start+1))
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}
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return crc
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}
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// 并发无断点续传的下载
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func (bucket Bucket) downloadFile(objectKey, filePath string, partSize int64, options []Option, routines int, uRange *unpackedRange) error {
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tempFilePath := filePath + TempFileSuffix
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listener := getProgressListener(options)
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// 如果文件不存在则创建，存在不清空，下载分片会重写文件内容
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fd, err := os.OpenFile(tempFilePath, os.O_WRONLY|os.O_CREATE, FilePermMode)
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if err != nil {
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return err
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}
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fd.Close()
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// 分割文件
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parts, enableCRC, expectedCRC, err := getDownloadParts(&bucket, objectKey, partSize, uRange)
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if err != nil {
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return err
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}
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jobs := make(chan downloadPart, len(parts))
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results := make(chan downloadPart, len(parts))
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failed := make(chan error)
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die := make(chan bool)
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var completedBytes int64
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totalBytes := getObjectBytes(parts)
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event := newProgressEvent(TransferStartedEvent, 0, totalBytes)
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publishProgress(listener, event)
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// 启动工作协程
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arg := downloadWorkerArg{&bucket, objectKey, tempFilePath, options, downloadPartHooker, enableCRC}
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for w := 1; w <= routines; w++ {
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go downloadWorker(w, arg, jobs, results, failed, die)
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}
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// 并发上传分片
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go downloadScheduler(jobs, parts)
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// 等待分片下载完成
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completed := 0
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for completed < len(parts) {
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select {
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case part := <-results:
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completed++
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completedBytes += (part.End - part.Start + 1)
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parts[part.Index].CRC64 = part.CRC64
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event = newProgressEvent(TransferDataEvent, completedBytes, totalBytes)
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publishProgress(listener, event)
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case err := <-failed:
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close(die)
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event = newProgressEvent(TransferFailedEvent, completedBytes, totalBytes)
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publishProgress(listener, event)
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return err
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}
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if completed >= len(parts) {
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break
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}
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}
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event = newProgressEvent(TransferCompletedEvent, completedBytes, totalBytes)
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publishProgress(listener, event)
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if enableCRC {
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actualCRC := combineCRCInParts(parts)
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err = checkDownloadCRC(actualCRC, expectedCRC)
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if err != nil {
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return err
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}
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}
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return os.Rename(tempFilePath, filePath)
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}
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// ----- 并发有断点的下载 -----
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const downloadCpMagic = "92611BED-89E2-46B6-89E5-72F273D4B0A3"
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type downloadCheckpoint struct {
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Magic string // magic
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MD5 string // cp内容的MD5
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FilePath string // 本地文件
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Object string // key
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ObjStat objectStat // 文件状态
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Parts []downloadPart // 全部分片
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PartStat []bool // 分片下载是否完成
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Start int64 // 起点
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End int64 // 终点
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enableCRC bool // 是否有CRC校验
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CRC uint64 // CRC校验值
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}
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type objectStat struct {
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Size int64 // 大小
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LastModified string // 最后修改时间
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Etag string // etag
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}
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// CP数据是否有效，CP有效且Object没有更新时有效
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func (cp downloadCheckpoint) isValid(bucket *Bucket, objectKey string, uRange *unpackedRange) (bool, error) {
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// 比较CP的Magic及MD5
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cpb := cp
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cpb.MD5 = ""
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js, _ := json.Marshal(cpb)
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sum := md5.Sum(js)
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b64 := base64.StdEncoding.EncodeToString(sum[:])
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if cp.Magic != downloadCpMagic || b64 != cp.MD5 {
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return false, nil
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}
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// 确认object没有更新
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meta, err := bucket.GetObjectDetailedMeta(objectKey)
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if err != nil {
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return false, err
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}
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objectSize, err := strconv.ParseInt(meta.Get(HTTPHeaderContentLength), 10, 0)
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if err != nil {
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return false, err
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}
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// 比较Object的大小/最后修改时间/etag
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if cp.ObjStat.Size != objectSize ||
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cp.ObjStat.LastModified != meta.Get(HTTPHeaderLastModified) ||
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cp.ObjStat.Etag != meta.Get(HTTPHeaderEtag) {
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return false, nil
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}
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// 确认下载范围是否变化
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if uRange != nil {
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start, end := adjustRange(uRange, objectSize)
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if start != cp.Start || end != cp.End {
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return false, nil
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}
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}
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return true, nil
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}
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// 从文件中load
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func (cp *downloadCheckpoint) load(filePath string) error {
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contents, err := ioutil.ReadFile(filePath)
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if err != nil {
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return err
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}
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err = json.Unmarshal(contents, cp)
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return err
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}
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// dump到文件
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func (cp *downloadCheckpoint) dump(filePath string) error {
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bcp := *cp
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// 计算MD5
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bcp.MD5 = ""
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js, err := json.Marshal(bcp)
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if err != nil {
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return err
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}
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sum := md5.Sum(js)
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b64 := base64.StdEncoding.EncodeToString(sum[:])
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bcp.MD5 = b64
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// 序列化
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js, err = json.Marshal(bcp)
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if err != nil {
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return err
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}
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// dump
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return ioutil.WriteFile(filePath, js, FilePermMode)
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}
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// 未完成的分片
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func (cp downloadCheckpoint) todoParts() []downloadPart {
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dps := []downloadPart{}
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for i, ps := range cp.PartStat {
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if !ps {
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dps = append(dps, cp.Parts[i])
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}
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}
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return dps
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}
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// 完成的字节数
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func (cp downloadCheckpoint) getCompletedBytes() int64 {
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var completedBytes int64
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for i, part := range cp.Parts {
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if cp.PartStat[i] {
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completedBytes += (part.End - part.Start + 1)
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}
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}
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return completedBytes
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}
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// 初始化下载任务
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func (cp *downloadCheckpoint) prepare(bucket *Bucket, objectKey, filePath string, partSize int64, uRange *unpackedRange) error {
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// cp
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cp.Magic = downloadCpMagic
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cp.FilePath = filePath
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cp.Object = objectKey
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// object
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meta, err := bucket.GetObjectDetailedMeta(objectKey)
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if err != nil {
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return err
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}
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objectSize, err := strconv.ParseInt(meta.Get(HTTPHeaderContentLength), 10, 0)
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if err != nil {
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return err
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}
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cp.ObjStat.Size = objectSize
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cp.ObjStat.LastModified = meta.Get(HTTPHeaderLastModified)
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cp.ObjStat.Etag = meta.Get(HTTPHeaderEtag)
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// parts
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cp.Parts, cp.enableCRC, cp.CRC, err = getDownloadParts(bucket, objectKey, partSize, uRange)
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if err != nil {
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return err
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}
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cp.PartStat = make([]bool, len(cp.Parts))
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for i := range cp.PartStat {
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cp.PartStat[i] = false
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}
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return nil
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}
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func (cp *downloadCheckpoint) complete(cpFilePath, downFilepath string) error {
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os.Remove(cpFilePath)
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return os.Rename(downFilepath, cp.FilePath)
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}
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// 并发带断点的下载
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func (bucket Bucket) downloadFileWithCp(objectKey, filePath string, partSize int64, options []Option, cpFilePath string, routines int, uRange *unpackedRange) error {
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tempFilePath := filePath + TempFileSuffix
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listener := getProgressListener(options)
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// LOAD CP数据
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dcp := downloadCheckpoint{}
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err := dcp.load(cpFilePath)
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if err != nil {
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os.Remove(cpFilePath)
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}
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// LOAD出错或数据无效重新初始化下载
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valid, err := dcp.isValid(&bucket, objectKey, uRange)
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if err != nil || !valid {
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if err = dcp.prepare(&bucket, objectKey, filePath, partSize, uRange); err != nil {
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return err
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}
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os.Remove(cpFilePath)
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}
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// 如果文件不存在则创建，存在不清空，下载分片会重写文件内容
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fd, err := os.OpenFile(tempFilePath, os.O_WRONLY|os.O_CREATE, FilePermMode)
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if err != nil {
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return err
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}
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fd.Close()
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// 未完成的分片
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parts := dcp.todoParts()
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jobs := make(chan downloadPart, len(parts))
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results := make(chan downloadPart, len(parts))
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failed := make(chan error)
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die := make(chan bool)
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completedBytes := dcp.getCompletedBytes()
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event := newProgressEvent(TransferStartedEvent, completedBytes, dcp.ObjStat.Size)
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publishProgress(listener, event)
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// 启动工作协程
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arg := downloadWorkerArg{&bucket, objectKey, tempFilePath, options, downloadPartHooker, dcp.enableCRC}
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for w := 1; w <= routines; w++ {
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go downloadWorker(w, arg, jobs, results, failed, die)
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}
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// 并发下载分片
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go downloadScheduler(jobs, parts)
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// 等待分片下载完成
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completed := 0
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for completed < len(parts) {
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select {
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case part := <-results:
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completed++
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dcp.PartStat[part.Index] = true
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dcp.Parts[part.Index].CRC64 = part.CRC64
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dcp.dump(cpFilePath)
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completedBytes += (part.End - part.Start + 1)
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event = newProgressEvent(TransferDataEvent, completedBytes, dcp.ObjStat.Size)
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publishProgress(listener, event)
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case err := <-failed:
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close(die)
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event = newProgressEvent(TransferFailedEvent, completedBytes, dcp.ObjStat.Size)
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publishProgress(listener, event)
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return err
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}
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if completed >= len(parts) {
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break
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}
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}
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event = newProgressEvent(TransferCompletedEvent, completedBytes, dcp.ObjStat.Size)
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publishProgress(listener, event)
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if dcp.enableCRC {
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actualCRC := combineCRCInParts(dcp.Parts)
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err = checkDownloadCRC(actualCRC, dcp.CRC)
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if err != nil {
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return err
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}
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}
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return dcp.complete(cpFilePath, tempFilePath)
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}
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