Golang : Command line ticker to show work in progress

Problem:

Your command line application is crunching data and you want your program to show the user that it is working. It is not a progress bar with percentage completion, but just a simple ticker to distract the user's attention. How to do that?

Solution:

Create an array of -,\,/' and -. Randomly selects one or iterates over the items in the array and display it.

Here you go!

 package main

 /*
  #include <stdio.h>
  #include <unistd.h>
  #include <termios.h>
  char getch(){
 char ch = 0;
 struct termios old = {0};
 fflush(stdout);
 if( tcgetattr(0, &old) < 0 ) perror("tcsetattr()");
 old.c_lflag &= ~ICANON;
 old.c_lflag &= ~ECHO;
 old.c_cc[VMIN] = 1;
 old.c_cc[VTIME] = 0;
 if( tcsetattr(0, TCSANOW, &old) < 0 ) perror("tcsetattr ICANON");
 if( read(0, &ch,1) < 0 ) perror("read()");
 old.c_lflag |= ICANON;
 old.c_lflag |= ECHO;
 if(tcsetattr(0, TCSADRAIN, &old) < 0) perror("tcsetattr ~ICANON");
 return ch;
  }
 */
 import "C"

 import (
 "fmt"
 "math/rand"
 "os"
 "time"
 )

 func main() {

 go func() {
 key := C.getch() // get single key hit without pressing Enter button
 fmt.Println()
 fmt.Println("Exiting ...")
 if key == 27 {
 os.Exit(0)
 }
 }()

 // recording in progress ticker. From good old DOS days.
 ticker := []string{
 "-",
 "\\",  //<--- need escape 
 "/",
 "|",
 }
 rand.Seed(time.Now().UnixNano())

 fmt.Println("Press ESC key to quit...")
 for {
 fmt.Printf("\rProcessing data now! [%v]", ticker[rand.Intn(len(ticker)-1)])
 }

 }

Run the code and you should see the ticker in action.

It is use in https://socketloop.com/tutorials/golang-save-webcamera-frames-to-video-file as well.

Happy coding!

References:

https://www.socketloop.com/tutorials/golang-overwrite-previous-output-with-count-down-timer

https://socketloop.com/tutorials/golang-randomly-pick-an-item-from-a-slice-array-example

http://stackoverflow.com/questions/14094190/golang-function-similar-to-getchar