Yii分析3：Yii日志记录

Yii的自带组件有一个很实用的日志记录组件，使用方法可以参考Yii官方文档：http://www.yiiframework.com/doc/guide/1.1/zh_cn/topics.logging，在文档中提到，只要我们在应用程序配置文件中配置了log组件，那么就可以使用

 

Yii::log($msg, $level, $category);

进行日志记录了。
配置项示例如下：

array(
    ......
    'preload'=>array('log'),
    'components'=>array(
        ......
        'log'=>array(
            'class'=>'CLogRouter',
            'routes'=>array(
                array(
                    'class'=>'CFileLogRoute',
                    'levels'=>'trace, info',
                    'categories'=>'system.*',
                ),
                array(
                    'class'=>'CEmailLogRoute',
                    'levels'=>'error, warning',
                    'emails'=>'[e-mail]',
                ),
            ),
        ),
    ),
)

 log组件的核心是CLogRouter，如果想使用多种方式记录日志，就必须配置routes，可用的route有：
•    CDbLogRoute: 将信息保存到数据库的表中。
•    CEmailLogRoute: 发送信息到指定的 Email 地址。
•    CFileLogRoute: 保存信息到应用程序 runtime 目录中的一个文件中。
•    CWebLogRoute: 将 信息 显示在当前页面的底部。
•    CProfileLogRoute: 在页面的底部显示概述（profiling）信息。
下面分析一下log的实现：
首先看一下CLogRouter的代码：

   /**
     * Initializes this application component.
     * This method is required by the IApplicationComponent interface.
     */
    public function init()
    {
        parent::init();
        foreach($this->_routes as $name=>$route)
        {
			//初始化从配置文件读取的route，保存在成员变量里
            $route=Yii::createComponent($route);
            $route->init();
            $this->_routes[$name]=$route;
        }
		//绑定事件，如果触发了一个onFlush事件，则调用CLogRouter的collectLogs方法
        Yii::getLogger()->attachEventHandler('onFlush',array($this,'collectLogs'));
		//绑定事件，如果触发了一个onEndRequest事件，则调用ClogRouter的processLogs方法
        Yii::app()->attachEventHandler('onEndRequest',array($this,'processLogs'));
}
    /**
     * Collects log messages from a logger.
     * This method is an event handler to the {@link CLogger::onFlush} event.
     * @param CEvent $event event parameter
     */
    public function collectLogs($event)
    {
        $logger=Yii::getLogger();
		//调用每个route的collectLogs方法
        foreach($this->_routes as $route)
        {
            if($route->enabled)
                $route->collectLogs($logger,false);
        }
    }

 

接着，我们看一下在调用Yii::log();时，发生了什么：

 

    /**
     * Logs a message.
     * Messages logged by this method may be retrieved via {@link CLogger::getLogs}
     * and may be recorded in different media, such as file, email, database, using
     * {@link CLogRouter}.
     * @param string $msg message to be logged
     * @param string $level level of the message (e.g. 'trace', 'warning', 'error'). It is case-insensitive.
     * @param string $category category of the message (e.g. 'system.web'). It is case-insensitive.
     */
    public static function log($msg,$level=CLogger::LEVEL_INFO,$category='application')
    {
        if(self::$_logger===null)
            self::$_logger=new CLogger;
        if(YII_DEBUG && YII_TRACE_LEVEL>0 && $level!==CLogger::LEVEL_PROFILE)
        {
            $traces=debug_backtrace();
            $count=0;
            foreach($traces as $trace)
            {
                if(isset($trace['file'],$trace['line']) && strpos($trace['file'],YII_PATH)!==0)
                {
                    $msg.="\nin ".$trace['file'].' ('.$trace['line'].')';
                    if(++$count>=YII_TRACE_LEVEL)
                        break;
                }
            }
        }
		//调用CLogger的log方法
        self::$_logger->log($msg,$level,$category);
    }

 

继续看CLogger：

 

class CLogger extends CComponent
{
const LEVEL_TRACE='trace';
const LEVEL_WARNING='warning';
const LEVEL_ERROR='error';
const LEVEL_INFO='info';
const LEVEL_PROFILE='profile';
/**
     * @var integer how many messages should be logged before they are flushed to destinations.
     * Defaults to 10,000, meaning for every 10,000 messages, the {@link flush} method will be
     * automatically invoked once. If this is 0, it means messages will never be flushed automatically.
     * @since 1.1.0
     */
public $autoFlush=10000;
……
/**
     * Logs a message.
     * Messages logged by this method may be retrieved back via {@link getLogs}.
     * @param string $message message to be logged
     * @param string $level level of the message (e.g. 'Trace', 'Warning', 'Error'). It is case-insensitive.
     * @param string $category category of the message (e.g. 'system.web'). It is case-insensitive.
     * @see getLogs
     */
    public function log($message,$level='info',$category='application')
{
	//将日志信息保存在成员变量（数组）中
        $this->_logs[]=array($message,$level,$category,microtime(true));
        $this->_logCount++;
		//如果数组数量到了autoFlush定义的数量，那么调用flush方法
        if($this->autoFlush>0 && $this->_logCount>=$this->autoFlush)
            $this->flush();
}
/**
     * Removes all recorded messages from the memory.
     * This method will raise an {@link onFlush} event.
     * The attached event handlers can process the log messages before they are removed.
     * @since 1.1.0
     */
    public function flush()
    {
	//触发onflush方法，这时会触发CLogRouter的onflush事件
	//参见上面CLogRouter的代码，会调用collectLogs方法
        $this->onFlush(new CEvent($this));
		//清空日志数据
        $this->_logs=array();
        $this->_logCount=0;
    }

 

回到CLogRouter，调用collectLogs实际是调用配置中的每一个Route的collectlogs方法
，这个方法是所有route继承自CLogRoute（注意，不是CLogRouter）的：

 

/**
     * Retrieves filtered log messages from logger for further processing.
     * @param CLogger $logger logger instance
     * @param boolean $processLogs whether to process the logs after they are collected from the logger
     */
    public function collectLogs($logger, $processLogs=false)
{
	//获取日志记录
        $logs=$logger->getLogs($this->levels,$this->categories);
        $this->logs=empty($this->logs) ? $logs : array_merge($this->logs,$logs);
        if($processLogs && !empty($this->logs))
        {
            if($this->filter!==null)
                Yii::createComponent($this->filter)->filter($this->logs);
			//调用processlog方法
            $this->processLogs($this->logs);
        }
    }
    /**
     * Processes log messages and sends them to specific destination.
     * Derived child classes must implement this method.
     * @param array $logs list of messages.  Each array elements represents one message
     * with the following structure:
     * array(
     *   [0] => message (string)
     *   [1] => level (string)
     *   [2] => category (string)
     *   [3] => timestamp (float, obtained by microtime(true));
     */
    //processlog是由CLogRoute的各个route子类实现的
    //例如数据库route用数据库存储，文件route用文件存储……
    abstract protected function processLogs($logs);

 

至此，整个记录日志的过程就清楚了，下图是类关系：