func downloadFile()

in s3plugin/restore.go [222:252]
29 lines of code
5 McCabe index (conditional complexity)

func downloadFile(sess *session.Session, config *PluginConfig, bucket string, fileKey string,
	file *os.File) (int64, time.Duration, error) {

	start := time.Now()
	downloader := s3manager.NewDownloader(sess, func(u *s3manager.Downloader) {
		u.PartSize = config.Options.DownloadChunkSize
	})

	totalBytes, err := getFileSize(downloader.S3, bucket, fileKey)
	if err != nil {
		return 0, -1, errors.Wrap(err, fmt.Sprintf("Error getting file size for %s in bucket %s", fileKey, bucket))
	}
	gplog.Verbose("File %s size = %d bytes", filepath.Base(fileKey), totalBytes)
	if totalBytes <= config.Options.DownloadChunkSize {
		buffer := &aws.WriteAtBuffer{}
		if _, err = downloader.Download(
			buffer,
			&s3.GetObjectInput{
				Bucket: aws.String(bucket),
				Key:    aws.String(fileKey),
			}); err != nil {
			return 0, -1, errors.Wrap(err, fmt.Sprintf("Error while downloading %s", fileKey))
		}
		if _, err = file.Write(buffer.Bytes()); err != nil {
			return 0, -1, err
		}
	} else {
		return downloadFileInParallel(sess, config.Options.DownloadConcurrency, config.Options.DownloadChunkSize, totalBytes, bucket, fileKey, file)
	}
	return totalBytes, time.Since(start), err
}