dejurin/index.html

## index.html
<!DOCTYPE html>

<html>
<head>
  <meta http-equiv="Content-type" content="text/html; charset=utf-8">
  <title>Pinger test</title>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js" type="text/javascript" charset="utf-8"></script>
</head>
<body>

<h1>Online user counter</h1>


<p id="counter">Users online: <span id="userCount">loading…</span></p>

<script type="text/javascript" charset="utf-8">
$().ready(function (){
  var token = '';
  var pinger = setInterval(function (){

    $.ajax({
      cache: false,
      data: {
        token: token,
      },
      timeout: 2500,
      type: 'GET',
      url: 'pinger.php',
      dataType: 'json',
      success: function (data, status, jqXHR){
        $('#userCount').text(data.userCount);
        token = data.token;
      }
    });

  }, 5000);
});
</script>


</body>
</html>

## pinger.php
<?php

// Look for token
$token = (isset($_GET['token']) && preg_match('/^[0-9a-f]{8}$/', $_GET['token'])) ? $_GET['token'] : false;

if (!$token) {
  $token = sprintf('%08x', crc32(microtime()));
}

// get current minute, build APC key
$quadrant = ceil(date_create()->format('s') / 15); // between 1-4
$previousQuadrant = $quadrant - 1 < 1 ? 4 : $quadrant - 1;
$key = 'pinger_'.$quadrant;
$previousKey = 'pinger_'.$previousQuadrant;

// get tokens for the last 30 seconds
$current = apc_fetch($key);
$previous = apc_fetch($previousKey);

if (!is_array($current)) {
  $current = array();
}

if (!is_array($previous)) {
  $previous = array();
}

// Add current token if not found
if (count($current) < 250 && !in_array($token, $current)) {
  $current[] = $token;
  apc_store($key, $current, 31);
}


// Build return object: userCount, token
$output = array(
  'userCount' => count($current) > 250 ? '250+' : count(array_unique(array_merge($current, $previous))),
  'token' => $token,
);

header('Content-Type: application/json');
print json_encode($output);
exit;
	<!DOCTYPE html>

	<html>
	<head>
	<meta http-equiv="Content-type" content="text/html; charset=utf-8">
	<title>Pinger test</title>
	<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js" type="text/javascript" charset="utf-8"></script>
	</head>
	<body>

	<h1>Online user counter</h1>


	<p id="counter">Users online: <span id="userCount">loading…</span></p>

	<script type="text/javascript" charset="utf-8">
	$().ready(function (){
	var token = '';
	var pinger = setInterval(function (){

	$.ajax({
	cache: false,
	data: {
	token: token,
	},
	timeout: 2500,
	type: 'GET',
	url: 'pinger.php',
	dataType: 'json',
	success: function (data, status, jqXHR){
	$('#userCount').text(data.userCount);
	token = data.token;
	}
	});

	}, 5000);
	});
	</script>


	</body>
	</html>
	<?php

	// Look for token
	$token = (isset($_GET['token']) && preg_match('/^[0-9a-f]{8}$/', $_GET['token'])) ? $_GET['token'] : false;

	if (!$token) {
	$token = sprintf('%08x', crc32(microtime()));
	}

	// get current minute, build APC key
	$quadrant = ceil(date_create()->format('s') / 15); // between 1-4
	$previousQuadrant = $quadrant - 1 < 1 ? 4 : $quadrant - 1;
	$key = 'pinger_'.$quadrant;
	$previousKey = 'pinger_'.$previousQuadrant;

	// get tokens for the last 30 seconds
	$current = apc_fetch($key);
	$previous = apc_fetch($previousKey);

	if (!is_array($current)) {
	$current = array();
	}

	if (!is_array($previous)) {
	$previous = array();
	}

	// Add current token if not found
	if (count($current) < 250 && !in_array($token, $current)) {
	$current[] = $token;
	apc_store($key, $current, 31);
	}


	// Build return object: userCount, token
	$output = array(
	'userCount' => count($current) > 250 ? '250+' : count(array_unique(array_merge($current, $previous))),
	'token' => $token,
	);

	header('Content-Type: application/json');
	print json_encode($output);
	exit;