protected function setReadPreferenceFromSlaveOkay($ok = true)
{
$result = $this->getSlaveOkayFromReadPreference();
$readPreference = new \MongoDB\Driver\ReadPreference($ok ? \MongoDB\Driver\ReadPreference::RP_SECONDARY_PREFERRED : \MongoDB\Driver\ReadPreference::RP_PRIMARY, $ok ? $this->readPreference->getTagSets() : []);
$this->readPreference = $readPreference;
return $result;
}