LogMemoryUsage.php

<?php
	/**
	 * Log memory usage.
	 * 
	 * Makes use of {@link https://gist.github.com/1849563 _log} and {@link https://gist.github.com/2880386 formatMemory}.
	 *
	 * @author Craig Anderson <craiga@craiga.id.au>
	 * @link https://gist.github.com/3336985
	 */
	protected function _logMemoryUsage()
	{
		$memoryUsage = memory_get_usage();

		if(is_null($this->_lastMemoryUsage))
		{
			$this->_log("Memory usage: %s", formatMemory($memoryUsage));
		}
		else
		{
			$change = $memoryUsage - $this->_lastMemoryUsage;
			$change_time = microtime(true) - $this->_lastMemoryUsageTime;
			$rate = $change_time == 0 ? 0 : $change / $change_time;
			$this->_log("Memory usage: %s; change since last time: %s; rate: %s per second", formatMemory($memoryUsage), formatMemory($change), formatMemory($rate));
		}
		$this->_lastMemoryUsage = $memoryUsage;
		$this->_lastMemoryUsageTime = microtime(true);
	}
	
	/**
	 * Last recorded memory usage.
	 */
	protected $_lastMemoryUsage = null;
	
	/**
	 * Last recorded memory usgae time.
	 */
	protected $_lastMemoryUsageTime = null;