Module and page caching for better performance

	function display($tpl = null,$params=array()){
		$this->paramBase = HIKASHOP_COMPONENT.'.'.$this->getName();
		$function = $this->getLayout();
		$this->params = $params;

		$config =& hikashop_config();
		$this->assignRef('config',$config);
		$module = hikashop_get('helper.module');
		$module->initialize($this);
		$this->paramBase.='_'.$this->params->get('main_div_name');
    
    $cid = $id = JRequest::getInt("cid",$this->params->get('selectparentlisting'));
    if ($cid == "12" || $cid == "35")
    {
      $cache_id = "hika" . $cid;
      if (!ds_use_cache($cache_id ,strtotime('-1 hour')))
      {
        ob_start();

        if(method_exists($this,$function)) $this->$function();
        parent::display($tpl);
        
        $html = ob_get_clean();
        echo ($html);

        ds_create_cache($cache_id, $html);  
      }
    }
    else
    {
		  if(method_exists($this,$function)) $this->$function();
		  parent::display($tpl);
    }
}

function ds_use_cache($cache_id, $ts=0) {
  $file = DS_CACHE.$cache_id;
  
  if(file_exists($file)){
    // and the file is readable
    if(is_readable($file)){
    
      $stale = false;
      $filets = filemtime($file);
      if ($ts) {
        if ($filets < $ts) {
          $stale = true;
        }
      }
      else if (date('Ymd', $filets) != date('Ymd')) {  
        $stale = true;
      }
    
      if ($stale == false) {
        // open the file for reading
        if($fp=@fopen($file,'r')){
          if(flock($fp, LOCK_SH))
          fpassthru($fp);
          flock($fp, LOCK_UN); 
          fclose($fp);
          return true;
        }
        fclose($fp);
      }
    }
  }
  return false;
}

function ds_create_cache($cache_id, $html)
{
  $file = DS_CACHE.$cache_id;
  if (file_exists($file)) {
    $fp=@fopen($file,'r+');
  } else {
    $fp=@fopen($file,'w');
  }
  if ($fp) {
    if(flock($fp, LOCK_EX)) {
      ftruncate($fp, 0);
      fwrite($fp,$html);
      flock($fp, LOCK_UN); 
    }
    fclose($fp);
  }
}