/**      * Parse a DSN string, which can have one of the following formats:      *      * - host:port      * - redis://user:pass@host:port/db?option1=val1&option2=val2      * - tcp://user:pass@host:port/db?option1=val1&option2=val2      *      * Note: the 'user' part of the DSN is not used.      *      * @param string $dsn A DSN string      * @return array An array of DSN compotnents, with 'false' values for any unknown components. e.g.      *               [host, port, db, user, pass, options]      */     public static function parseDsn($dsn)     {         if ($dsn == '') {             // Use a sensible default for an empty DNS string             $dsn = 'redis://' . self::DEFAULT_HOST;         }         $parts = parse_url($dsn);         // Check the URI scheme         $validSchemes = array('redis', 'tcp');         if (isset($parts['scheme']) && ! in_array($parts['scheme'], $validSchemes)) {             throw new \InvalidArgumentException("Invalid DSN. Supported schemes are " . implode(', ', $validSchemes));         }         // Allow simple 'hostname' format, which `parse_url` treats as a path, not host.         if ( ! isset($parts['host']) && isset($parts['path'])) {             $parts['host'] = $parts['path'];             unset($parts['path']);         }         // Extract the port number as an integer         $port = isset($parts['port']) ? intval($parts['port']) : self::DEFAULT_PORT;         // Get the database from the 'path' part of the URI         $database = false;         if (isset($parts['path'])) {             // Strip non-digit chars from path             $database = intval(preg_replace('/[^0-9]/', '', $parts['path']));         }         // Extract any 'user' and 'pass' values         $user = isset($parts['user']) ? $parts['user'] : false;         $pass = isset($parts['pass']) ? $parts['pass'] : false;         // Convert the query string into an associative array         $options = array();         if (isset($parts['query'])) {             // Parse the query string into an array             parse_str($parts['query'], $options);         }         return array(             $parts['host'],             $port,             $database,             $user,             $pass,             $options,         );     }