SlightPHP\Cache_File::get PHP Method

    function get($key)
    {
        $realFile = $this->_getDir($key);
        if (!$realFile || !is_file($realFile)) {
            return false;
        }
        $fp = fopen($realFile, "r");
        if (!$fp) {
            return false;
        }
        flock($fp, LOCK_SH);
        $timeout = trim(fgets($fp));
        if (!empty($timeout)) {
            $timenow = time();
            if ($timeout == -1 || $timenow < $timeout) {
                $data = fread($fp, filesize($realFile));
                flock($fp, LOCK_UN);
                fclose($fp);
                return unserialize($data);
            } else {
                //过期了，应该删除这个文件，但为了性能考虑，不删除
            }
        }
        flock($fp, LOCK_UN);
        fclose($fp);
        return false;
    }