code: public function processJob(JobInterface $job, QueueInterface $queue)
      {
          if (!$queue instanceof MongoQueue) {
              return;
          }
  
          if ($job instanceOf QueueAwareInterface) {
              $job->setQueue($queue);
          }
  
          try {
              return $job->execute();
          } catch (\Exception $exception) {
              $this->getLogger()->err('Job execution thrown exception: ' . get_class($exception));
  
              if ($job instanceOf ResultProviderInterface) {
                  $job->setResult(JobResult::failure($exception->getMessage(), [$exception->getTraceAsString()]));
              } else {
                  $this->getLogger()->err($exception->getMessage(), [$exception->getTraceAsString()]);
              }
  
              return ProcessJobEvent::JOB_STATUS_FAILURE;
          }
      }
docs: Process job handler.
  
  @param JobInterface   $job
  @param QueueInterface $queue
  
  @return int|void