CI框架源码阅读---------基准测试类Benchmark.php

[php]

/**

* CodeIgniter

*

* An open source application development framework for PHP 5.1.6 or newer

*

* @package CodeIgniter

* @author ExpressionEngine Dev Team

* @copyright Copyright (c) 2008 - 2011, EllisLab, Inc.

* @license http://codeigniter.com/user_guide/license.html

* @link http://codeigniter.com

* @since Version 1.0

* @filesource

*/

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

/**

* CodeIgniter Benchmark Class

*

* This class enables 能够 you to mark points and calculate 计算 the time difference 差异

* between them. Memory consumption can also be displayed.

*

* @package CodeIgniter

* @subpackage Libraries

* @category Libraries

* @author ExpressionEngine Dev Team

* @link http://codeigniter.com/user_guide/libraries/benchmark.html

*/

class CI_Benchmark {

/**

* List of all benchmark markers and when they were added

* 用来存储基准测试类标记的数组

* @var array

*/

var $marker = array();

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

/**

* Set a benchmark marker

* 设置一个标记点

* Multiple calls to this function can be made so that several

* execution points can be timed

*

* @access public

* @param string $name name of the marker

* @return void

*/

function mark($name)

{

// 在程序的任意地方调用方法时，会记录当前的时间点。

$this->marker[$name] = microtime();

}

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

/**

* Calculates the time difference between two marked points.

* 计算出两个时间点之间的时间。

* If the first parameter is empty this function instead returns the

* {elapsed_time} pseudo-variable 虚假变量. This permits 许可 the full system

* execution time to be shown in a template. The output class will

* swap the real value for this variable.

*

* @access public

* @param string a particular marked point

* @param string a particular marked point

* @param integer the number of decimal places

* @return mixed

*/

function elapsed_time($point1 = '', $point2 = '', $decimals = 4)

{

/*

* 如果没有给出明确的时间点，那么会计算出整个程序运行的时间。

* 怎么可以做到计算出整个程序的运行时间的呢？其实执行此计算的是Output组件。

* 而调用Benchmark::elapsed_time();（无参数）的时候，实质上先返回的并不是

* 整个程序运行的时间，也不可能做到，实质返回的是一个{elapsed_time}标签，然后

* Output在处理输出的时候，再计算出整个程序运行时间，因为处理输出阶段程序可以视

* 为处于最后阶段，于是可以近似计算出总时间，然后把输出中的{elapsed_time}替换掉。

* 下面的memory_usage()原理相同。

*/

if ($point1 == '')

{

return '{elapsed_time}';

}

if ( ! isset($this->marker[$point1]))

{

return '';

}

if ( ! isset($this->marker[$point2]))

{

$this->marker[$point2] = microtime();

}

//这里为什么要用到list，是因为microtime();返回值是“msec sec”的格式。

list($sm, $ss) = explode(' ', $this->marker[$point1]);

list($em, $es) = explode(' ', $this->marker[$point2]);

return number_format(($em + $es) - ($sm + $ss), $decimals);

}

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

/**

* Memory Usage

*

* This function returns the {memory_usage} pseudo-variable.

* This permits it to be put it anywhere in a template

* without the memory being calculated until the end.

* The output class will swap the real value for this variable.

* www.2cto.com

* @access public

* @return string

*/

function memory_usage()

{

return '{memory_usage}';

}

}

// END CI_Benchmark class

/* End of file Benchmark.php */

/* Location: ./system/core/Benchmark.php */