~~~
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
* 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 能夠 you to mark points and calculate 計算 the time difference 差異
* 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
* 用來存儲基準測試類標記的數組
* @var array
*/
var $marker = array();
// --------------------------------------------------------------------
/**
* Set a benchmark marker
* 設置一個標記點
* 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)
{
// 在程序的任意地方調用方法時，會記錄當前的時間點。
$this->marker[$name] = microtime();
}
// --------------------------------------------------------------------
/**
* Calculates the time difference between two marked points.
* 計算出兩個時間點之間的時間。
* If the first parameter is empty this function instead returns the
* {elapsed_time} pseudo-variable 虛假變量. This permits 許可 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 = '', $decimals = 4)
{
/*
* 如果沒有給出明確的時間點，那么會計算出整個程序運行的時間。
* 怎么可以做到計算出整個程序的運行時間的呢？其實執行此計算的是Output組件。
* 而調用Benchmark::elapsed_time();（無參數）的時候，實質上先返回的并不是
* 整個程序運行的時間，也不可能做到，實質返回的是一個{elapsed_time}標簽，然后
* Output在處理輸出的時候，再計算出整個程序運行時間，因為處理輸出階段程序可以視
* 為處于最后階段，于是可以近似計算出總時間，然后把輸出中的{elapsed_time}替換掉。
* 下面的memory_usage()原理相同。
*/
if ($point1 == '')
{
return '{elapsed_time}';
}
if ( ! isset($this->marker[$point1]))
{
return '';
}
if ( ! isset($this->marker[$point2]))
{
$this->marker[$point2] = microtime();
}
//這里為什么要用到list，是因為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.
*
* @access public
* @return string
*/
function memory_usage()
{
return '{memory_usage}';
}
}
// END CI_Benchmark class
/* End of file Benchmark.php */
/* Location: ./system/core/Benchmark.php */
~~~
