In case someone would like to use this solrClient with solr v.4.0 and higher i've prepared my own commit function
class solr {
public function delete($query ) {
$this->_client->deleteByQuery($query);
$this->commit();
}
public function commit() {
$solrConfig= // array with solr host, port, path to collection (/solr/my_collection),
$solrAddress = $solrConfig['hostname'] . ':' . $solrConfig['port'] . $solrConfig['path'];
$output = array();
$response = exec('curl ' . $solrAddress . '/update?commit=true', $output);
return $output;
}
}