CodeIgniter - 如何有选择地缓存输出？

Question

我的应用程序允许注册用户发布内容。在顶部栏上，与许多社交应用程序一样，登录时可以看到他们的头像等。

我的问题是，当使用CodeIgniter的输出缓存时，标头中的用户特定内容会被缓存。

这是因为首先我通过MY_Controller加载用户特定的逻辑，然后由所有其他控制器扩展。

当我放置

$this->output->cache(MINUTES);

在加载我的主页的控制器中，它最终还会缓存生成该缓存页面的用户的头像和名称。

是否有人建议选择性地仅缓存公共内容的最佳方法是什么？很高兴在需要时发布更多代码。

Answer 1

我确信如果我错了，有人会纠正我，但我相信codeigniter缓存只允许缓存整页。还有一些额外的库可以实现部分页面缓存，请查看phil sturgeons的工作： http://getsparks.org/packages/cache/show

我个人的方法是不打扰页面缓存，只使用更具选择性的数据库缓存 - 但如果你想/需要页面缓存，那么我认为上面是唯一的方法

Answer 2

Codeigniter不会按访问者和经过身份验证的用户分开缓存。

否则，您可以通过覆盖输出类自行完成此操作。 在CI / application / core中创建MY_Output.php

这是我最新项目的代码。

class MY_Output extends CI_Output

{

/**
 * Write Cache
 *
 * @param   string  $output Output data to cache
 * @return  void
 */
public function _write_cache($output)
{
    $CI =& get_instance();

    //-XXX CUSTOM------------------------------------
    $cache_path = $this->cachePath();
    //-----------------------------------------------

    if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path))
    {
        log_message('error', 'Unable to write cache file: '.$cache_path);
        return;
    }

    $uri = $CI->config->item('base_url')
        .$CI->config->item('index_page')
        .$CI->uri->uri_string();

    if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
    {
        if (is_array($cache_query_string))
        {
            $uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
        }
        else
        {
            $uri .= '?'.$_SERVER['QUERY_STRING'];
        }
    }

    $cache_path .= md5($uri);

    if ( ! $fp = @fopen($cache_path, 'w+b'))
    {
        log_message('error', 'Unable to write cache file: '.$cache_path);
        return;
    }

    if ( ! flock($fp, LOCK_EX))
    {
        log_message('error', 'Unable to secure a file lock for file at: '.$cache_path);
        fclose($fp);
        return;
    }

    // If output compression is enabled, compress the cache
    // itself, so that we don't have to do that each time
    // we're serving it
    if ($this->_compress_output === TRUE)
    {
        $output = gzencode($output);

        if ($this->get_header('content-type') === NULL)
        {
            $this->set_content_type($this->mime_type);
        }
    }

    $expire = time() + ($this->cache_expiration * 60);

    // Put together our serialized info.
    $cache_info = serialize(array(
        'expire'    => $expire,
        'headers'   => $this->headers
    ));

    $output = $cache_info.'ENDCI--->'.$output;

    for ($written = 0, $length = self::strlen($output); $written < $length; $written += $result)
    {
        if (($result = fwrite($fp, self::substr($output, $written))) === FALSE)
        {
            break;
        }
    }

    flock($fp, LOCK_UN);
    fclose($fp);

    if ( ! is_int($result))
    {
        @unlink($cache_path);
        log_message('error', 'Unable to write the complete cache content at: '.$cache_path);
        return;
    }

    chmod($cache_path, 0640);
    log_message('debug', 'Cache file written: '.$cache_path);

    // Send HTTP cache-control headers to browser to match file cache settings.
    $this->set_cache_header($_SERVER['REQUEST_TIME'], $expire);
}

// --------------------------------------------------------------------

/**
 * Update/serve cached output
 *
 * @uses    CI_Config
 * @uses    CI_URI
 *
 * @param   object  &$CFG   CI_Config class instance
 * @param   object  &$URI   CI_URI class instance
 * @return  bool    TRUE on success or FALSE on failure
 */
public function _display_cache(&$CFG, &$URI)
{
    //-XXX CUSTOM------------------------------------
    $cache_path = $this->cachePath($CFG);
    //$cache_path = ($CFG->item('cache_path') === '') ? APPPATH.'cache/' : $CFG->item('cache_path');
    //-----------------------------------------------

    // 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;

    if (($cache_query_string = $CFG->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
    {
        if (is_array($cache_query_string))
        {
            $uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
        }
        else
        {
            $uri .= '?'.$_SERVER['QUERY_STRING'];
        }
    }

    $filepath = $cache_path.md5($uri);

    if ( ! file_exists($filepath) OR ! $fp = @fopen($filepath, 'rb'))
    {
        return FALSE;
    }

    flock($fp, LOCK_SH);

    $cache = (filesize($filepath) > 0) ? fread($fp, filesize($filepath)) : '';

    flock($fp, LOCK_UN);
    fclose($fp);

    // Look for embedded serialized file info.
    if ( ! preg_match('/^(.*)ENDCI--->/', $cache, $match))
    {
        return FALSE;
    }

    $cache_info = unserialize($match[1]);
    $expire = $cache_info['expire'];

    $last_modified = filemtime($filepath);

    // Has the file expired?
    if ($_SERVER['REQUEST_TIME'] >= $expire && is_really_writable($cache_path))
    {
        // If so we'll delete it.
        @unlink($filepath);
        log_message('debug', 'Cache file has expired. File deleted.');
        return FALSE;
    }

    // Send the HTTP cache control headers
    $this->set_cache_header($last_modified, $expire);

    // Add headers from cache file.
    foreach ($cache_info['headers'] as $header)
    {
        $this->set_header($header[0], $header[1]);
    }

    //-XXX CUSTOM------------------------------------
    $exTime = $this->executionTime();
    setcookie('exe_time', "$exTime", time()+120, '/');
    //-----------------------------------------------

    // Display the cache
    $this->_display(self::substr($cache, self::strlen($match[0])));
    log_message('debug', 'Cache file is current. Sending it to browser.');
    return TRUE;
}

// --------------------------------------------------------------------

/**
 * Delete cache
 *
 * @param   string  $uri    URI string
 * @return  bool
 */
public function delete_cache($uri = '')
{
    $CI =& get_instance();
    //-XXX CUSTOM------------------------------------
    $cache_path = $CI->config->item('cache_path');
    $cache_path = ($cache_path === '') ? APPPATH.'cache/' : $cache_path;
    //-----------------------------------------------


    if ( ! is_dir($cache_path))
    {
        log_message('error', 'Unable to find cache path: '.$cache_path);
        return FALSE;
    }

    if (empty($uri))
    {
        $uri = $CI->uri->uri_string();

        if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
        {
            if (is_array($cache_query_string))
            {
                $uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
            }
            else
            {
                $uri .= '?'.$_SERVER['QUERY_STRING'];
            }
        }
    }


    //-XXX CUSTOM------------------------------------
    $passed = TRUE;
    $path1 = $cache_path.'xmember/'.md5($CI->config->item('base_url').$CI->config->item('index_page').ltrim($uri, '/'));
    if ( ! @unlink($path1))
    {
        log_message('error', 'Unable to delete cache file for '.$uri);
        $passed = FALSE;
    }

    $path2 = $cache_path.'xvisitor/'.md5($CI->config->item('base_url').$CI->config->item('index_page').ltrim($uri, '/'));
    if ( ! @unlink($path2))
    {
        log_message('error', 'Unable to delete cache file for '.$uri);
        $passed = FALSE;
    }
    //-----------------------------------------------

    return $passed;
}


private function cachePath(&$CFG=false)
{
    $hasSession = !empty($_COOKIE[COOKIE_CUSTOMER_SESSION_ID]);

    if(empty($CFG)) {
        $CI =& get_instance();
        $CFG = $CI->config;
    }
    $path = $CFG->item('cache_path');
    $path = empty($path) ? APPPATH.'cache/' : $path;
    $path .= $hasSession?'xmember/':'xvisitor/';

    return $path;
}

function executionTime()
{
    $time = microtime();
    $time = explode(' ', $time);
    $time = $time[1] + $time[0];
    $total_time = round(($time - LOAD_PAGE_START), 4); //second unit
    return $total_time;
}

}