src/Queue.php
public function push($job)
    {
        $event = new PushEvent([
            'job' => $job,
            'ttr' => $this->pushTtr ?: (
                $job instanceof RetryableJobInterface
                    ? $job->getTtr()
                    : $this->ttr
            ),
            'delay' => $this->pushDelay ?: 0,
            'priority' => $this->pushPriority,
        ]);
        $this->pushTtr = null;
        $this->pushDelay = null;
        $this->pushPriority = null;

        $this->trigger(self::EVENT_BEFORE_PUSH, $event);
        if ($event->handled) {
            return null;
        }

        if ($this->strictJobType && !($event->job instanceof JobInterface)) {
            throw new InvalidArgumentException('Job must be instance of JobInterface.');
        }

        if (!is_numeric($event->ttr)) {
            throw new InvalidArgumentException('Job TTR must be integer.');
        }
        $event->ttr = (int) $event->ttr;
        if ($event->ttr <= 0) {
            throw new InvalidArgumentException('Job TTR must be greater that zero.');
        }

        if (!is_numeric($event->delay)) {
            throw new InvalidArgumentException('Job delay must be integer.');
        }
        $event->delay = (int) $event->delay;
        if ($event->delay < 0) {
            throw new InvalidArgumentException('Job delay must be positive.');
        }

        $message = $this->serializer->serialize($event->job);
        $event->id = $this->pushMessage($message, $event->ttr, $event->delay, $event->priority);
        $this->trigger(self::EVENT_AFTER_PUSH, $event);

        return $event->id;
    }
public function push($job)
    {
        $event = new PushEvent([
            'job' => $job,
            'ttr' => $this->pushTtr ?: (
                $job instanceof RetryableJobInterface
                    ? $job->getTtr()
                    : $this->ttr
            ),
            'delay' => $this->pushDelay ?: 0,
            'priority' => $this->pushPriority,
        ]);
        $this->pushTtr = null;
        $this->pushDelay = null;
        $this->pushPriority = null;

        $this->trigger(self::EVENT_BEFORE_PUSH, $event);
        if ($event->handled) {
            return null;
        }

        if ($this->strictJobType && !($event->job instanceof JobInterface)) {
            throw new InvalidArgumentException('Job must be instance of JobInterface.');
        }

        if (!is_numeric($event->ttr)) {
            throw new InvalidArgumentException('Job TTR must be integer.');
        }
        $event->ttr = (int) $event->ttr;
        if ($event->ttr <= 0) {
            throw new InvalidArgumentException('Job TTR must be greater that zero.');
        }

        if (!is_numeric($event->delay)) {
            throw new InvalidArgumentException('Job delay must be integer.');
        }
        $event->delay = (int) $event->delay;
        if ($event->delay < 0) {
            throw new InvalidArgumentException('Job delay must be positive.');
        }

        $message = $this->serializer->serialize($event->job);
        $event->id = $this->pushMessage($message, $event->ttr, $event->delay, $event->priority);
        $this->trigger(self::EVENT_AFTER_PUSH, $event);

        return $event->id;
    }
Pushes job into queue.

@param JobInterface|mixed $job
@return string|null id of a job message