CI框架源码翻阅-基准测试类Benchmark.php

<?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.	 *	 * @access	public	 * @return	string	 */	function memory_usage()	{		return '{memory_usage}';	}}// END CI_Benchmark class/* End of file Benchmark.php *//* Location: ./system/core/Benchmark.php */