ระบบ cache ไม่ทำงานอยากทราบว่าผิดตรงไหน ไม่เก็บไฟล์ cache เลยรันไม่ขึ้นช่วยด้วยครับ

<?php 
    header('Content-Type: application/json');
    header("Access-Control-Allow-Origin: *");
   

	$url = 'https://www.google.com';
	$sources = curl($url);

    $cache_active = true;
    $cache_time = 7200;
    $cache_path = 'cache/test.cac';
    if($cache_active && file_exists($cache_path) && (time() - filemtime($cache_path) < $cache_time)) {
        $data = @file_get_contents($cache_path);
        echo $data;
    } else {
        $data = @file_get_contents($sources);
        $json = json_decode($data,TRUE);

        if ($json['title'][0]['title'] != NULL) {
           @file_put_contents($cache_path, $data);
        }
        echo $data;
    }


function curl($url)
{
  $ch = @curl_init();
  curl_setopt($ch, CURLOPT_URL, $url);
  $head[] = "Connection: keep-alive";
  $head[] = "Keep-Alive: 300";
  $head[] = "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7";
  $head[] = "Accept-Language: en-us,en;q=0.5";
  curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.124 Safari/537.36');
  curl_setopt($ch, CURLOPT_ENCODING, 'gzip');
  curl_setopt($ch, CURLOPT_HTTPHEADER, $head);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
  curl_setopt($ch, CURLOPT_TIMEOUT, 15);
  curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 15);
  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);
  $page = curl_exec($ch);
  curl_close($ch);
  return $page;
}

?>