Elapsed Timing - Class

<?php
namespace app\system;

use app\system\MicroTime;

class ElapsedTiming {

    public $break;

    private $startTime = null;

    private $stopTime = null;

    // Constructor for Timing class
    public function __construct($break = "<br />") {
        $this->break = $break;
        // Set timezone
        date_default_timezone_set('UTC');
    }

    // Set start time
    public function start() {
        $this->startTime = new MicroTime();
    }

    // Set stop/end time
    public function stop() {
        $this->stopTime = new MicroTime();
    }

    // Returns time elapsed from start
    public function getElapsedTime($when = null) {
        $nowMT = new MicroTime($when);
        $diff = $nowMT->diff($this->startTime);
        return number_format($diff->elapsedTime(), 3);

    }

    // Returns total execution time
    public function getTotalExecutionTime() {
        if (!$this->stopTime) {
            return false;
        }
        $diff = $this->stopTime->diff($this->startTime);
        return $diff->elapsedTime();
    }

    // Returns start time, stop time and total execution time
    public function getFullStats() {
        if (!$this->stopTime) {
            return false;
        }

        $stats = array();
        $stats['startTime'] = $this->startTime->asDateTimeStr();
        $stats['stopTime'] = $this->stopTime->asDateTimeStr();
        $stats['total_execution_time'] = $this->getTotalExecutionTime();

        return $stats;
    }

    // Prints time elapsed from start
    public function printElapsedTime($prompt = '') {
        echo $this->break . $this->break;
        echo "Elapsed time: " . $this->getElapsedTime();
        echo $this->break . $this->break;
    }

    // Prints total execution time
    public function printTotalExecutionTime() {
        if (!$this->stopTime) {
            return false;
        }

        echo $this->break . $this->break;
        echo "Total execution time: " . $this->getTotalExecutionTime();
        echo $this->break . $this->break;
    }

    // Prints start time, stop time and total execution time
    public function printFullStats($prompt = '') {
        if (!$this->stopTime) {
            return false;
        }

        echo $this->break . $this->break;
        if (!empty($prompt)) {
              echo $prompt;
              echo $this->break;
        }
        echo "Script start date and time   : " . $this->startTime->asDateTimeStr();
        echo $this->break;
        echo "Script stop end date and time: " . $this->stopTime->asDateTimeStr();
        echo $this->break;
        echo "Total execution time         : " . $this->getTotalExecutionTime();
        echo $this->break . $this->break;
    }

    /*
     * return MicroTime objects
     */
    public function startTime()
    {
        return $this->startTime;
    }

    public function stopTime()
    {
        return $this->stopTime;
    }

    /*
    public function elapsedTime()
    {
        $nowMT = new MicroTime();
        return $nowMT->diff($this->startTime)->elapsedTime();
    }
     *
     */
}