Function copyProgress

cli/command/container/cp.go:70–122

(ctx context.Context, dst io.Writer, header string, total *int64)

}

func copyProgress(ctx context.Context, dst io.Writer, header string, total *int64) (func(), <-chan struct{}) {
	done := make(chan struct{})
	if !streams.NewOut(dst).IsTerminal() {
		close(done)
		return func() {}, done
	}

	fmt.Fprint(dst, aec.Save)
	fmt.Fprint(dst, "Preparing to copy...")

	restore := func() {
		fmt.Fprint(dst, aec.Restore)
		fmt.Fprint(dst, aec.EraseLine(aec.EraseModes.All))
	}

	go func() {
		defer close(done)
		fmt.Fprint(dst, aec.Hide)
		defer fmt.Fprint(dst, aec.Show)

		fmt.Fprint(dst, aec.Restore)
		fmt.Fprint(dst, aec.EraseLine(aec.EraseModes.All))
		fmt.Fprint(dst, header)

		var last int64
		fmt.Fprint(dst, progressHumanSize(last))

		buf := bytes.NewBuffer(nil)
		ticker := time.NewTicker(copyProgressUpdateThreshold)
		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				n := atomic.LoadInt64(total)
				if n == last {
					// Don't write to the terminal, if we don't need to.
					continue
				}

				// Write to the buffer first to avoid flickering and context switching
				fmt.Fprint(buf, aec.Column(uint(len(header)+1)))
				fmt.Fprint(buf, aec.EraseLine(aec.EraseModes.Tail))
				fmt.Fprint(buf, progressHumanSize(n))

				buf.WriteTo(dst)
				buf.Reset()
				last += n
			}
		}
	}()
	return restore, done
}

// newCopyCommand creates a new `docker cp` command
func newCopyCommand(dockerCLI command.Cli) *cobra.Command {