src/Tracker.php
public function start($msg = null, array $extraInfo = [])
    {
        if ($this->status != self::NOT_STARTED) {
            throw new TrackerException("Cannot start tracker that was already started");
        }

        $this->status = self::RUNNING;
        $this->startTime = microtime(true);

        $tick = new Tick($this, Tick::SUCCESS, $msg, $extraInfo, 0);
        $this->dispatcher->dispatch(Events::TRACKER_START, $tick);
        $this->lastTick = $tick;
    }
public function start($msg = null, array $extraInfo = [])
    {
        if ($this->status != self::NOT_STARTED) {
            throw new TrackerException("Cannot start tracker that was already started");
        }

        $this->status = self::RUNNING;
        $this->startTime = microtime(true);

        $tick = new Tick($this, Tick::SUCCESS, $msg, $extraInfo, 0);
        $this->dispatcher->dispatch(Events::TRACKER_START, $tick);
        $this->lastTick = $tick;
    }
Start processing

If this method is not called explicitely, it will automatically
be called upon first tick

@param string $msg Optional message to include
@param array  $extraInfo