Caching and headers

[eluser]narkaT[/eluser]
Nice idea

I have a small suggestion to reduce the code-redundancy with the CI-core and reduce overhead.
we can determinate if a file is expired without first run unserialze:

Code:

class MY_Output extends CI_Output {

    /**
     * Write a Cache File
     *
     * @access    public
     * @return    void
     */    
    function _write_cache($output)
    {
        parent::_write_cache( serialize(array('headers' => $this->headers, 'output' => $output)) );
    }

    /**
     * Update/serve a cached file
     *
     * @access    public
     * @return    void
     */    
    function _display_cache(&$CFG, &$URI)
    {
        $cache_path = ($CFG->item('cache_path') == '') ? BASEPATH.'cache/' : $CFG->item('cache_path');
            
        if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path))
        {
            return FALSE;
        }
        
        // Build the file path.  The file name is an MD5 hash of the full URI
        $uri =    $CFG->item('base_url').
                $CFG->item('index_page').
                $URI->uri_string;
                
        $filepath = $cache_path.md5($uri);
        
        if ( ! @file_exists($filepath))
        {
            return FALSE;
        }
    
        if ( ! $fp = @fopen($filepath, FOPEN_READ))
        {
            return FALSE;
        }
            
        flock($fp, LOCK_SH);
        
        $cache = '';
        if (filesize($filepath) > 0)
        {
            $cache = fread($fp, filesize($filepath));
        }
    
        flock($fp, LOCK_UN);
        fclose($fp);
                    
        // Strip out the embedded timestamp        
        if ( ! preg_match("/(\d+TS--->)/", $cache, $match))
        {
            return FALSE;
        }
        
        // Has the file expired? If so we'll delete it.
        if (time() >= trim(str_replace('TS--->', '', $match['1'])))
        {        
            @unlink($filepath);
            log_message('debug', "Cache file has expired. File deleted");
            return FALSE;
        }

        // Display the cache
        $cache = unserialize(str_replace($match['0'], '', $cache));
        $this->headers = $cache['headers'];
        $this->_display($cache['output']);
        log_message('debug', "Cache file is current. Sending it to browser.");        
        return TRUE;
    }
}

I've tested the code with some gziped js/css and images fetched from a DB