Qfyilyi

I'm trying to send a packet from my server to ping a client every few seconds in an infinite loop at all times.

This is the code I am running:

const dgram = require('dgram');

const message = Buffer.from('Some bytes');

const clientPing = dgram.createSocket('udp4');



const pinging = true;



function ping() {

  clientPing.send("Hi Uno", 8888, 'XXX.XX.XX.XXX', (err) => {

    clientPing.close();

  });

}



function sleep(time, callback) {

    var stop = new Date().getTime();

    while(new Date().getTime() < stop + time) {

        ;

    }

    callback();

}



function loop() {

  while(pinging == true) {

    sleep(3000, function() {

      ping();

      console.log('ping');

    });

  }

}



loop();

What's weird is that the console logs the string ping just fine at the given interval but the packet is never sent and never reaches my client. But when I run just ping(); outside of the loop the packet hits the client.

Udp isn't supposed to wait for a response after it sends the packet and doesn't wait for a response. What am I missing here?

As @tkausl says, you're blocking the event loop. Don't use that sleep() function. Try something like this instead:

function loop() {

  if (!pinging) {

    return;

  }

  ping();

  console.log('ping');

  setTimeout(loop, 3000);

}



loop();

So I finally got it behave properly using this:

function loop() {



  setInterval(() => {

    clientPing.send("Hi Uno", 8888, 'XXX.XX.XX.XXX', (err) => {

    });

  }, 5000);



}



loop();

So now the Pi running this pings my arduino client successfully every 5s, the arduino then replies with temp and humidity data, the Pi server then catches it and pushes that to mongo.