/**
* Checks if workers are still valid.
*
* @param string $heartbeatAt
* @return mixed|string
*/
public function validateQueue($heartbeatAt)
{
if (microtime(true) > $heartbeatAt) {
$this->queue->rewind();
while ($this->queue->valid()) {
$message = new MultipartMessage($this->workerChannel);
$message->setBody("HEARTBEAT");
$message->wrap($this->queue->key(), null);
$message->send();
$this->queue->next();
}
$heartbeatAt = microtime(true) + $this->config->getInterval();
}
$this->queue->purgeQueue();
return $heartbeatAt;
}