| package future |
| |
| import ( |
| "bytes" |
| "crypto/sha256" |
| "errors" |
| "fmt" |
| "io" |
| "math/rand" |
| "net/http" |
| "time" |
| ) |
| |
| func Seed() { |
| rand.Seed(time.Now().UTC().UnixNano()) |
| } |
| |
| func ComputeId(content io.Reader) (string, error) { |
| h := sha256.New() |
| if _, err := io.Copy(h, content); err != nil { |
| return "", err |
| } |
| return fmt.Sprintf("%x", h.Sum(nil)[:8]), nil |
| } |
| |
| func HumanDuration(d time.Duration) string { |
| if seconds := int(d.Seconds()); seconds < 1 { |
| return "Less than a second" |
| } else if seconds < 60 { |
| return fmt.Sprintf("%d seconds", seconds) |
| } else if minutes := int(d.Minutes()); minutes == 1 { |
| return "About a minute" |
| } else if minutes < 60 { |
| return fmt.Sprintf("%d minutes", minutes) |
| } else if hours := int(d.Hours()); hours == 1 { |
| return "About an hour" |
| } else if hours < 48 { |
| return fmt.Sprintf("%d hours", hours) |
| } else if hours < 24*7*2 { |
| return fmt.Sprintf("%d days", hours/24) |
| } else if hours < 24*30*3 { |
| return fmt.Sprintf("%d weeks", hours/24/7) |
| } else if hours < 24*365*2 { |
| return fmt.Sprintf("%d months", hours/24/30) |
| } |
| return fmt.Sprintf("%d years", d.Hours()/24/365) |
| } |
| |
| func randomBytes() io.Reader { |
| return bytes.NewBuffer([]byte(fmt.Sprintf("%x", rand.Int()))) |
| } |
| |
| func RandomId() string { |
| id, _ := ComputeId(randomBytes()) // can't fail |
| return id |
| } |
| |
| func Go(f func() error) chan error { |
| ch := make(chan error) |
| go func() { |
| ch <- f() |
| }() |
| return ch |
| } |
| |
| // Pv wraps an io.Reader such that it is passed through unchanged, |
| // but logs the number of bytes copied (comparable to the unix command pv) |
| func Pv(src io.Reader, info io.Writer) io.Reader { |
| var totalBytes int |
| data := make([]byte, 2048) |
| r, w := io.Pipe() |
| go func() { |
| for { |
| if n, err := src.Read(data); err != nil { |
| w.CloseWithError(err) |
| return |
| } else { |
| totalBytes += n |
| fmt.Fprintf(info, "--> %d bytes\n", totalBytes) |
| if _, err = w.Write(data[:n]); err != nil { |
| return |
| } |
| } |
| } |
| }() |
| return r |
| } |
| |
| // Request a given URL and return an io.Reader |
| func Download(url string, stderr io.Writer) (*http.Response, error) { |
| var resp *http.Response |
| var err error = nil |
| if resp, err = http.Get(url); err != nil { |
| return nil, err |
| } |
| if resp.StatusCode >= 400 { |
| return nil, errors.New("Got HTTP status code >= 400: " + resp.Status) |
| } |
| return resp, nil |
| } |
| |
| // Reader with progress bar |
| type progressReader struct { |
| reader io.ReadCloser // Stream to read from |
| output io.Writer // Where to send progress bar to |
| read_total int // Expected stream length (bytes) |
| read_progress int // How much has been read so far (bytes) |
| last_update int // How many bytes read at least update |
| } |
| |
| func (r *progressReader) Read(p []byte) (n int, err error) { |
| read, err := io.ReadCloser(r.reader).Read(p) |
| r.read_progress += read |
| |
| // Only update progress for every 1% read |
| update_every := int(0.01 * float64(r.read_total)) |
| if r.read_progress-r.last_update > update_every || r.read_progress == r.read_total { |
| fmt.Fprintf(r.output, "%d/%d (%.0f%%)\r", |
| r.read_progress, |
| r.read_total, |
| float64(r.read_progress)/float64(r.read_total)*100) |
| r.last_update = r.read_progress |
| } |
| // Send newline when complete |
| if err == io.EOF { |
| fmt.Fprintf(r.output, "\n") |
| } |
| |
| return read, err |
| } |
| func (r *progressReader) Close() error { |
| return io.ReadCloser(r.reader).Close() |
| } |
| func ProgressReader(r io.ReadCloser, size int, output io.Writer) *progressReader { |
| return &progressReader{r, output, size, 0, 0} |
| } |