Stopwatch.php

<?php

class Stopwatch
{
    /**
     * @var array[]
     */
    private $marks = [];

    /**
     * @var float|null
     */
    private $lastMark = null;

    /**
     * Mark point in time
     *
     * @param string $label
     *
     * @return float
     */
    public function mark(string $label = ""): float
    {
        $now = microtime(true);
        $this->marks[] = ["time" => $now, "label" => $label];
        $diff = null !== $this->lastMark ? $now - $this->lastMark : 0;
        $this->lastMark = $now;
        return $diff;
    }

    /**
     * Get all marks
     *
     * @return array[] ["total" => float, "split" => float, "label" => string][]
     */
    public function getMarks(): array
    {
        $marks = [];
        $first = $last = reset($this->marks)["time"];
        foreach ($this->marks as $mark) {
            $marks[] = ["total" => $mark["time"] - $first, "split" => $mark["time"] - $last, "label" => $mark["label"]];
            $last = $mark["time"];
        }
        return $marks;
    }

    /**
     * Get time elapsed between first and last mark
     *
     * @return float
     */
    public function elapsed(): float
    {
        return null !== $this->lastMark ? $this->lastMark - $this->marks[0]["time"] : 0;
    }

}