progress

io.Reader and io.Writer with progress and remaining time estimation.

Usage

ctx := context.Background()

// get a reader and the total expected number of bytes
s := `Now that's what I call progress`
size := len(s)
r := progress.NewReader(strings.NewReader(s))

// Start a goroutine printing progress
go func() {
	ctx := context.Background()
	progressChan := progress.NewTicker(ctx, r, size, 1*time.Second)
	for p := range progressChan {
		fmt.Printf("\r%v remaining...", p.Remaining().Round(time.Second))
	}
	fmt.Println("\rdownload is completed")
}()

// use the Reader as normal
if _, err := io.Copy(dest, r); err != nil {
	log.Fatalln(err)
}

1. Wrap an io.Reader or io.Writer with NewReader and NewWriter respectively
2. Capture the total number of expected bytes
3. Use progress.NewTicker to get a channel on which progress updates will be sent
4. Start a Goroutine to periodically check the progress, and do something with it - like log it
5. Use the readers and writers as normal