system/Database/Query.php
public function setDuration(float $start, float $end = null)
	{
		$this->startTime = $start;

		if (is_null($end))
		{
			$end = microtime(true);
		}

		$this->endTime = $end;

		return $this;
	}
public function setDuration(float $start, float $end = null)
	{
		$this->startTime = $start;

		if (is_null($end))
		{
			$end = microtime(true);
		}

		$this->endTime = $end;

		return $this;
	}
Records the execution time of the statement using microtime(true)
for it's start and end values. If no end value is present, will
use the current time to determine total duration.

@param float $start
@param float $end

@return $this