gistfile1.txt

<?php
global $interface;
global $mesurements;
global $file;
$interface = "br-fftr:";
$mesurements = 120;
$file = "/var/www/html/realtime-stats/bandwidth.json";

function data_add(&$array, $value) {
	global $mesurements;
	array_push($array, $value);
	while(sizeof($array) > $mesurements)
		array_shift($array);
}


function getMesurement() {
	global $interface;
	$raw = file_get_contents("/proc/net/dev");
	$time = time();
	$lines = explode("\n", $raw);
	foreach($lines as $line) {
		$line = trim($line);
		$line = preg_replace("/ +/", " ", $line);
		$columns = explode(" ", $line);

		if($columns[0] === $interface) {
			$in = $columns[1];
			$out = $columns[9];
			return array($time, $in, $out);
		}
	}
}

function doDelta($previous, $current) {
	return array(
		$current[0],
		$current[1]-$previous[1],
		$current[2]-$previous[2]
	);
}

function save($data) {
	global $file;
	$content = json_encode($data);
	file_put_contents($file,$content);
}


$data = array();
$previous = getMesurement();
while (true) {
	$current = getMesurement();
	$dataPoint = doDelta($previous, $current);
	$previous = $current;

	data_add($data, $dataPoint);
	save($data);

	print_r($dataPoint);
	sleep (1);
}