src/core/DeCaptchaAbstract.php
protected function executionDelayed($delay = 0, $callback = null)
    {
        $time = microtime(true);
        $timePassed = $time - $this->lastRunTime;
        if ($timePassed < $delay) {
            usleep(($delay - $timePassed) * 1000000);
        }
        $this->lastRunTime = microtime(true);

        return $callback instanceof \Closure ? $callback($this) : $callback;
    }
protected function executionDelayed($delay = 0, $callback = null)
    {
        $time = microtime(true);
        $timePassed = $time - $this->lastRunTime;
        if ($timePassed < $delay) {
            usleep(($delay - $timePassed) * 1000000);
        }
        $this->lastRunTime = microtime(true);

        return $callback instanceof \Closure ? $callback($this) : $callback;
    }
Задержка выполнения.

@param int           $delay    Количество секунд
@param \Closure|null $callback

@return mixed