izzum\statemachine\persistence\PDO::getEntityIds PHP Method

    public function getEntityIds($machine, $state = null)
    {
        $connection = $this->getConnection();
        $prefix = $this->getPrefix();
        $query = 'SELECT se.entity_id FROM ' . $prefix . 'statemachine_entities AS se
                JOIN ' . $prefix . 'statemachine_states AS ss ON (se.state = ss.state AND
                se.machine = ss.machine) WHERE se.machine = :machine';
        $output = array();
        try {
            if ($state != null) {
                $query .= ' AND se.state = :state';
            }
            $statement = $connection->prepare($query);
            $statement->bindParam(":machine", $machine);
            if ($state != null) {
                $statement->bindParam(":state", $state);
            }
            $result = $statement->execute();
            if ($result === false) {
                throw new Exception($this->getErrorInfo($statement));
            }
            $rows = $statement->fetchAll();
            if ($rows === false) {
                throw new Exception("failed getting rows: " . $this->getErrorInfo($statement));
            }
            foreach ($rows as $row) {
                $output[] = $row['entity_id'];
            }
        } catch (\Exception $e) {
            throw new Exception($e->getMessage(), Exception::PERSISTENCE_LAYER_EXCEPTION, $e);
        }
        return $output;
    }