| package future |
| |
| import ( |
| "bytes" |
| "crypto/sha256" |
| "fmt" |
| "io" |
| "math/rand" |
| "os/exec" |
| "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 |
| } |
| |
| // Curl makes an http request by executing the unix command 'curl', and returns |
| // the body of the response. If `stderr` is not nil, a progress bar will be |
| // written to it. |
| func Curl(url string, stderr io.Writer) (io.Reader, error) { |
| curl := exec.Command("curl", "-#", "-L", url) |
| output, err := curl.StdoutPipe() |
| if err != nil { |
| return nil, err |
| } |
| curl.Stderr = stderr |
| if err := curl.Start(); err != nil { |
| return nil, err |
| } |
| return output, nil |
| } |