How to Get Number of CPU Cores using PHP Function (Platform Independent)

function getNumberOfCPUs() {
  $ans = 1;
  if (is_file('/proc/cpuinfo')) {
    $cpuinfo = file_get_contents('/proc/cpuinfo');
    preg_match_all('/^processor/m', $cpuinfo, $matches);
    $ans = count($matches[0]);
  } else if ('WIN' === strtoupper(substr(PHP_OS, 0, 3))) {
    $process = @popen('wmic cpu get NumberOfCores', 'rb');
    if (false !== $process) {
      fgets($process);
      $ans = intval(fgets($process));
      pclose($process);
    }
  } else {
    $ps = @popen('sysctl -a', 'rb');
    if (false !== $ps) {
      $output = stream_get_contents($ps);
      preg_match('/hw.ncpu: (\d+)/', $output, $matches);
      if ($matches) {
        $ans = intval($matches[1][0]);
      }
      pclose($ps);
    }
  }  
  return $ans;
}