Core/Toolbox/Date/Timer.php
public function start()
    {
        if ($this->running) {
            Throw new \RuntimeException('Timer is already running.');
        }

        $this->start = microtime(true);
        $this->checkpoints['start'] = $this->start;
        $this->running = true;

        return $this;
    }
public function start()
    {
        if ($this->running) {
            Throw new \RuntimeException('Timer is already running.');
        }

        $this->start = microtime(true);
        $this->checkpoints['start'] = $this->start;
        $this->running = true;

        return $this;
    }
Starts timer and creates first checkpoint

@throws \RuntimeException

@return Timer