public function calculateRetryDelay($retry_iteration)
{
if ($retry_iteration > 0) {
$retry_delay = $retry_iteration * $this->initial_retry_delay * $this->retry_delay_coefficient;
// Since $retry_delay is in milliseconds multiply it by 1000 to return microseconds
return $retry_delay * 1000;
} else {
return 0;
}
}