Method Do

parallel_download.go:219–274

(ctx ...context.Context)

}

func (pd *ParallelDownload) Do(ctx ...context.Context) error {
	err := pd.ensure()
	if err != nil {
		return err
	}
	for i := 0; i < pd.concurrency; i++ {
		go pd.startWorker(ctx...)
	}
	resp := pd.client.Head(pd.url).Do(ctx...)
	if resp.Err != nil {
		return resp.Err
	}
	if resp.ContentLength <= 0 {
		return fmt.Errorf("bad content length: %d", resp.ContentLength)
	}
	pd.lastIndex = int(math.Ceil(float64(resp.ContentLength)/float64(pd.segmentSize))) - 1
	pd.wg.Add(1)
	go pd.mergeFile()
	go func() {
		pd.wg.Wait()
		close(pd.wgDoneCh)
	}()
	totalBytes := resp.ContentLength
	start := int64(0)
	for i := 0; ; i++ {
		end := start + (pd.segmentSize - 1)
		if end > (totalBytes - 1) {
			end = totalBytes - 1
		}
		task := &downloadTask{
			index:      i,
			rangeStart: start,
			rangeEnd:   end,
		}
		pd.taskCh <- task
		if end < (totalBytes - 1) {
			start = end + 1
			continue
		}
		break
	}
	select {
	case <-pd.wgDoneCh:
		if pd.client.DebugLog {
			if pd.filename != "" {
				pd.client.log.Debugf("download completed from %s to %s", pd.url, pd.filename)
			} else {
				pd.client.log.Debugf("download completed for %s", pd.url)
			}
		}
		close(pd.doneCh)
	case err := <-pd.errCh:
		return err
	}
	return nil
}

func (pd *ParallelDownload) getOutputFile() (io.Writer, error) {