CI源码分析-Output.php


CodeIgniter.php 引入的第七个核心文件($OUT)。输出类是个核心类,它的功能只有一个:发送 Web 页面内容到请求的浏览器。 如果你开启缓存,它也负责 缓存 你的 Web 页面。

缓存机制

通过源码可知,写在controller方法用的echo等输出内容是无法缓存下来的。因为Output只缓存参数 public $final_output; 存储的内容。而该参数只能由append_output参数(该参数在 load->view时调用。)

zlib.output_compression

对页面尽兴Gzip压缩

一般而言,页面文件开启gzip压缩以后,其体积可以减小60%~90%,对于文字类站点,可以节省下大量的带宽与用户等待时间。但是不论是iis还是apache默认都只压缩html类静态文件,对于php文件需要模块配置才可支持(iis7.5中开启动态+静态压缩也可以),于是利用php自身功能到达gzip的效果也成为一项合理的诉求。参考地址

Mime types

参考连接

字符串操作

字符串比较

strcmp strncmp strcasecmp strncasecmp

字符串解析

mixed sscanf ( string $str , string $format [, mixed &$... ] )

数组操作

mixed current ( array &$array )

array array_map ( callable $callback , array $arr1 [, array $... ] )

array_map() 返回一个数组,该数组包含了 arr1 中的所有单元经过 callback 作用过之后的单元。callback
接受的参数数目应该和传递给 array_map() 函数的数组数目一致。

mixed array_shift ( array &$array )

array_shift() 将 array 的第一个单元移出并作为结果返回,将 array
的长度减一并将所有其它单元向前移动一位。所有的数字键名将改为从零开始计数,文字键名将不变。

array headers_list ( void )

headers_list() will return a list of headers to be sent to the browser
/ client. To determine whether or not these headers have been sent
yet, use headers_sent().

array array_merge ( array $array1 [, array $... ] )

array_merge() 将一个或多个数组的单元合并起来,一个数组中的值附加在前一个数组的后面。返回作为结果的数组。

如果输入的数组中有相同的字符串键名,则该键名后面的值将覆盖前一个值。然而,如果数组包含数字键名,后面的值将不会覆盖原来的值,而是附加到后面。

如果只给了一个数组并且该数组是数字索引的,则键名会以连续方式重新索引。

bool ob_start ([ callback $output_callback [, int $chunk_size [, bool $erase ]]] )

此函数将打开输出缓冲。当输出缓冲激活后,脚本将不会输出内容(除http标头外),相反需要输出的内容被存储在内部缓冲区中。

参考地址

string ob_gzhandler ( string $buffer , int $mode )

ob_gzhandler()目的是用在ob_start()中作回调函数,以方便将gz
编码的数据发送到支持压缩页面的浏览器。在ob_gzhandler()真正发送压缩过的数据之前,该
函数会确定(判定)浏览器可以接受哪种类型内容编码(”gzip”,”deflate”,或者根本什么都不支持),然后 返回相应的输出。
所有可以发送正确头信息表明他自己可以接受压缩的网页的浏览器,都可以支持。 All browsers are supported since
it’s up to the browser to send the correct header saying that it
accepts compressed web pages. 如果一个浏览器不支持压缩过的页面,此函数返回FALSE。

bool flock ( resource $handle , int $operation [, int &$wouldblock ] )

flock() 允许执行一个简单的可以在任何平台中使用的读取/写入模型(包括大部分的 Unix 派生版和甚至是 Windows)。

array array_intersect_key ( array $array1 , array $array2 [, array $ ... ] )

array_intersect_key() 返回一个数组,该数组包含了所有出现在 array1 中并同时出现在所有其它参数数组中的键名的值。

array array_flip ( array $trans )

array_flip() 返回一个反转后的 array,例如 trans 中的键名变成了值,而 trans 中的值成了键名。

注意 trans 中的值需要能够作为合法的键名,例如需要是 integer 或者
string。如果值的类型不对将发出一个警告,并且有问题的键/值对将不会反转。

如果同一个值出现了多次,则最后一个键名将作为它的值,所有其它的都丢失了。

_zlib_oc = (bool) ini_get('zlib.output_compression');
        $this->_compress_output = (
            $this->_zlib_oc === FALSE
            && config_item('compress_output') === TRUE
            && extension_loaded('zlib')
        );

        // Get mime types for later
        $this->mimes =& get_mimes();

        log_message('info', 'Output Class Initialized');
    }

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

    /**
     * Get Output
     *
     * Returns the current output string.
     *
     * @return    string
     */
    public function get_output()
    {
        return $this->final_output;
    }

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

    /**
     * Set Output
     *
     * Sets the output string.
     *
     * @param    string    $output    Output data
     * @return    CI_Output
     */
    public function set_output($output)
    {
        $this->final_output = $output;
        return $this;
    }

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

    /**
     * Append Output
     *
     * Appends data onto the output string.
     *
     * @param    string    $output    Data to append
     * @return    CI_Output
     */
    public function append_output($output)
    {
        $this->final_output .= $output;
        return $this;
    }

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

    /**
     * Set Header
     *
     * Lets you set a server header which will be sent with the final output.
     *
     * Note: If a file is cached, headers will not be sent.
     * @todo    We need to figure out how to permit headers to be cached.
     *
     * @param    string    $header        Header
     * @param    bool    $replace    Whether to replace the old header value, if already set
     * @return    CI_Output
     */
    public function set_header($header, $replace = TRUE)
    {
        // 不再对 content-length 进行设置(如果开启了 zlib.output_compression)
        // If zlib.output_compression is enabled it will compress the output,
        // but it will not modify the content-length header to compensate for
        // the reduction, causing the browser to hang waiting for more data.
        // We'll just skip content-length in those cases.
        if ($this->_zlib_oc && strncasecmp($header, 'content-length', 14) === 0)
        {
            return $this;
        }

        $this->headers[] = array($header, $replace);
        return $this;
    }

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

    /**
     * Set Content-Type Header
     * 设置 mime type (Content-Type)
     *
     * @param    string    $mime_type    Extension of the file we're outputting
     * @param    string    $charset    Character set (default: NULL)
     * @return    CI_Output
     */
    public function set_content_type($mime_type, $charset = NULL)
    {
        if (strpos($mime_type, '/') === FALSE)
        {
            //.txt => text/plain 
            $extension = ltrim($mime_type, '.');

            // Is this extension supported?
            if (isset($this->mimes[$extension]))
            {
                $mime_type =& $this->mimes[$extension];

                //取出数组第一个
                if (is_array($mime_type))
                {
                    $mime_type = current($mime_type);
                }
            }
        }

        $this->mime_type = $mime_type;

        if (empty($charset))
        {
            $charset = config_item('charset');
        }

        $header = 'Content-Type: '.$mime_type
            .(empty($charset) ? '' : '; charset='.$charset);

        $this->headers[] = array($header, TRUE);
        return $this;
    }

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

    /**
     * Get Current Content-Type Header
     * 从$this->headers取出content-type
     *
     * @return    string    'text/html', if not already set
     */
    public function get_content_type()
    {
        for ($i = 0, $c = count($this->headers); $i < $c; $i++)
        {
            if (sscanf($this->headers[$i][0], 'Content-Type: %[^;]', $content_type) === 1)
            {
                return $content_type;
            }
        }

        return 'text/html';
    }

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

    /**
     * Get Header
     *
     * @param    string    $header_name
     * @return    string
     */
    public function get_header($header)
    {
        // Combine headers already sent with our batched headers
        // 合并重复后者合并前者
        $headers = array_merge(
            // We only need [x][0] from our multi-dimensional array
            // 取出 aaa: true 的 aaa
            array_map('array_shift', $this->headers),
            headers_list()
        );

        if (empty($headers) OR empty($header))
        {
            return NULL;
        }

        for ($i = 0, $c = count($headers); $i < $c; $i++)
        {
            if (strncasecmp($header, $headers[$i], $l = strlen($header)) === 0)
            {
                return trim(substr($headers[$i], $l+1));
            }
        }

        return NULL;
    }

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

    /**
     * Set HTTP Status Header
     *
     * As of version 1.7.2, this is an alias for common function
     * set_status_header().
     *
     * @param    int    $code    Status code (default: 200)
     * @param    string    $text    Optional message
     * @return    CI_Output
     */
    public function set_status_header($code = 200, $text = '')
    {
        set_status_header($code, $text);
        return $this;
    }

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

    /**
     * Enable/disable Profiler
     *
     * @param    bool    $val    TRUE to enable or FALSE to disable
     * @return    CI_Output
     */
    public function enable_profiler($val = TRUE)
    {
        $this->enable_profiler = is_bool($val) ? $val : TRUE;
        return $this;
    }

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

    /**
     * Set Profiler Sections
     * 程序分析器
     *
     * Allows override of default/config settings for
     * Profiler section display.
     *
     * @param    array    $sections    Profiler sections
     * @return    CI_Output
     */
    public function set_profiler_sections($sections)
    {
        if (isset($sections['query_toggle_count']))
        {
            $this->_profiler_sections['query_toggle_count'] = (int) $sections['query_toggle_count'];
            unset($sections['query_toggle_count']);
        }

        foreach ($sections as $section => $enable)
        {
            $this->_profiler_sections[$section] = ($enable !== FALSE);
        }

        return $this;
    }

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

    /**
     * Set Cache
     *
     * @param    int    $time    Cache expiration time in seconds
     * @return    CI_Output
     */
    public function cache($time)
    {
        $this->cache_expiration = is_numeric($time) ? $time : 0;
        return $this;
    }

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

    /**
     * Display Output
     *
     * Processes and sends finalized output data to the browser along
     * with any server headers and profile data. It also stops benchmark
     * timers so the page rendering(显示) speed and memory usage can be shown.
     *
     * Note: All "view" data is automatically put into $this->final_output
     *     by controller class.
     *
     * @uses    CI_Output::$final_output
     * @param    string    $output    Output data override
     * @return    void
     */
    public function _display($output = '')
    {
        // Note:  We use load_class() because we can't use $CI =& get_instance()
        // since this function is sometimes called by the caching mechanism,
        // which happens before the CI super object is available.
        $BM =& load_class('Benchmark', 'core');
        $CFG =& load_class('Config', 'core');

        // Grab the super object if we can.
        if (class_exists('CI_Controller', FALSE))
        {
            $CI =& get_instance();
        }

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

        // Set the output data
        if ($output === '')
        {
            $output =& $this->final_output;
        }

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

        // Do we need to write a cache file? Only if the controller does not have its
        // own _output() method and we are not dealing with a cache file, which we
        // can determine by the existence of the $CI object above
        if ($this->cache_expiration > 0 && isset($CI) && ! method_exists($CI, '_output'))
        {
            $this->_write_cache($output);
        }

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

        // Parse out the elapsed time and memory usage,
        // then swap the pseudo-variables with the data
        // 统计时间
        $elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');

        //渲染模版
        if ($this->parse_exec_vars === TRUE)
        {
            $memory    = round(memory_get_usage() / 1024 / 1024, 2).'MB';
            $output = str_replace(array('{elapsed_time}', '{memory_usage}'), array($elapsed, $memory), $output);
        }

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

        // Is compression requested?
        if (isset($CI) // This means that we're not serving a cache file, if we were, it would already be compressed
            && $this->_compress_output === TRUE
            && isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
        {
            //打开输出缓冲区,此时没有将内容发送到客户端
            ob_start('ob_gzhandler');
        }

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

        // Are there any server headers to send?
        // 设置头部
        if (count($this->headers) > 0)
        {
            foreach ($this->headers as $header)
            {
                @header($header[0], $header[1]);
            }
        }

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

        // Does the $CI object exist?
        // If not we know we are dealing with a cache file so we'll
        // simply echo out the data and exit.
        if ( ! isset($CI))
        {
            if ($this->_compress_output === TRUE)
            {
                if (isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
                {
                    header('Content-Encoding: gzip');
                    header('Content-Length: '.strlen($output));
                }
                else
                {
                    // User agent doesn't support gzip compression,
                    // so we'll have to decompress our cache
                    $output = gzinflate(substr($output, 10, -8));
                }
            }

            echo $output;
            log_message('info', 'Final output sent to browser');
            log_message('debug', 'Total execution time: '.$elapsed);
            return;
        }

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

        // Do we need to generate profile data?
        // If so, load the Profile class and run it.
        if ($this->enable_profiler === TRUE)
        {
            $CI->load->library('profiler');
            if ( ! empty($this->_profiler_sections))
            {
                $CI->profiler->set_sections($this->_profiler_sections);
            }

            // If the output data contains closing  and  tags
            // we will remove them and add them back after we insert the profile data
            $output = preg_replace('|.*?|is', '', $output, -1, $count).$CI->profiler->run();
            if ($count > 0)
            {
                $output .= '';
            }
        }

        // Does the controller contain a function named _output()?
        // If so send the output there.  Otherwise, echo it.
        if (method_exists($CI, '_output'))
        {
            $CI->_output($output);
        }
        else
        {
            echo $output; // Send it to the browser!
        }

        log_message('info', 'Final output sent to browser');
        log_message('debug', 'Total execution time: '.$elapsed);
    }

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

    /**
     * Write Cache
     *
     * @param    string    $output    Output data to cache
     * @return    void
     */
    public function _write_cache($output)
    {
        $CI =& get_instance();
        $path = $CI->config->item('cache_path');
        $cache_path = ($path === '') ? APPPATH.'cache/' : $path;

        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($fp, LOCK_EX))
        {
            // If output compression is enabled, compress the cache
            // itself, so that we don't have to do that each time
            // we're serving it
            if ($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, $length = strlen($output); $written < $length; $written += $result)
            {
                if (($result = fwrite($fp, substr($output, $written))) === FALSE)
                {
                    break;
                }
            }

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

        fclose($fp);

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

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

    /**
     * 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)
    {
        $cache_path = ($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?
        // 过期
        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;
        }
        else
        {
            // Or else 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]);
        }

        // Display the cache
        $this->_display(substr($cache, 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();
        $cache_path = $CI->config->item('cache_path');
        if ($cache_path === '')
        {
            $cache_path = APPPATH.'cache/';
        }

        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();

            // get 参数是否会影响缓存
            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'];
                }
            }
        }

        $cache_path .= md5($CI->config->item('base_url').$CI->config->item('index_page').ltrim($uri, '/'));

        if ( ! @unlink($cache_path))
        {
            log_message('error', 'Unable to delete cache file for '.$uri);
            return FALSE;
        }

        return TRUE;
    }

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

    /**
     * Set Cache Header
     *
     * Set the HTTP headers to match the server-side file cache settings
     * in order to reduce bandwidth.
     * 
     * 最后一次缓存时间  过期时间(dead_line)
     *
     * @param    int    $last_modified    Timestamp of when the page was last modified
     * @param    int    $expiration    Timestamp of when should the requested page expire from cache
     * @return    void
     */
    public function set_cache_header($last_modified, $expiration)
    {
        //生存时间
        $max_age = $expiration - $_SERVER['REQUEST_TIME'];

        //如果时间一致,那么返回HTTP状态码304(不返回文件内容),客户端接到之后,就直接把本地缓存文件显示到浏览器中。 如果时间不一致,就返回HTTP状态码200和新的文件内容,客户端接到之后,会丢弃旧文件,把新文件缓存起来,并显示到浏览器中。
        if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && $last_modified <= strtotime($_server['http_if_modified_since'])) { 客户端已经执行了get,但文件未变化 $this->set_status_header(304);
            exit;
        }
        else
        {
            //过期了
            header('Pragma: public');
            //指示客户机可以接收生存期不大于指定时间(以秒为单位)的响应。
            header('Cache-Control: max-age='.$max_age.', public');
            //过期时间
            header('Expires: '.gmdate('D, d M Y H:i:s', $expiration).' GMT');
            //最后更新时间
            header('Last-modified: '.gmdate('D, d M Y H:i:s', $last_modified).' GMT');
        }
    }

}

文章作者: Fengit
版权声明: 本博客所有文章除特別声明外,均采用 CC BY 4.0 许可协议。转载请注明来源 Fengit !
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