php class to get singlton sqlite connection

Sqliter.php

namespace Manny;

/**
 * SQLite Connection Manager
 *
*/

class Sqliter
{
    protected $sqlite = null;

    /**
     * @param $dbname
     * @param $path
     */
    public function __construct($dbname,$path)
    {
        $this->dbname = $dbname;
        $this->dirpath = $path;
    }

    public function close()
    {
        try {
            $this->sqlite->close();
            $this->sqlite = null;
        } catch (\Exception $e){
            $this->sqlite = null;
        }
        return true;
    }

    public function getConn(){

        $allowed_memory = ini_get('memory_limit');
        if($allowed_memory != -1){
            $lastChar = strtoupper(substr($allowed_memory,'-1'));
            if(in_array($lastChar,['K','M','G'])){
                $allowed_memory = (int) $allowed_memory;
                switch ($lastChar){
                    case 'K': $allowed_memory *= 1024;break;
                    case 'M': $allowed_memory *= 1024*1024;break;
                    case 'G': $allowed_memory *= 1024*1024*1024;
                }
            }
            $current_memory = memory_get_usage(true);
            $mem_ratio = $current_memory / $allowed_memory;
            if($mem_ratio > 0.9) throw new \Exception('REACHED_MEMORY_LIMIT');
        }

        try {
            if(is_object($this->sqlite)){
                $this->sqlite->query('select 1');
            } else {
                $dbfile = $this->dirpath.'/'.$this->dbname.'.db';
                if(! is_file($dbfile)){
                    exec('touch '.$dbfile.';chmod 777 '.$dbfile);
                }
                $sqlite = new \SQLite3($dbfile, SQLITE3_OPEN_READWRITE | SQLITE3_OPEN_CREATE);
                $sqlite->enableExceptions(true);
                $sqlite->exec('PRAGMA journal_mode =WAL;'); // FOR PERFORMANCE, CONCURRENCY
                $this->sqlite = $sqlite;
            }
            return $this->sqlite;
        } catch (\Exception $e){
            $this->sqlite = null;
            time_nanosleep(0,10000000);
            return $this->getConn();
        }
    }

}