[TYPO3-core] RFC #11770: Feature: mysql_ping wrapper

[Dan Osipov]

Ries van Twisk wrote:
> Looking at class.ux_t3lib_db.php,
> 
> in the case of DBAL you can connect to multiple database so you might 
> want to test all connected databases and
> do something appropriate OR at least log a message that this function 
> does not support DBAL and
> only will ONYL ping a native mysql DB.
> 
> However just returning TRUE might lead to incorrect decisions for a 
> programmer when using this function and DBAL with non-mysql databases,
> or one native DB and a non-native DB...

The PHPDoc comment to the function in DBAL basically states that. I 
don't think there is a better alternative - do you?

> 
> 
> One potential problem I see with this function is that mysql_ping can 
> reconnect!!!! (really stupid decission of these people.....)
> 
> "Checks whether or not the connection to the server is working. If it 
> has gone down, an automatic reconnection is attempted. This function can 
> be used by scripts that remain idle for a long while, to check whether 
> or not the server has closed the connection and reconnect if necessary."
> 
> that means that the function sql_ping does a double connect!!!! THis 
> doesn't sounds right to me.....

I think the manual is wrong. I've used the function on several versions 
of MySQL, and it returns FALSE instead of reconnecting. That's why I 
implemented a reconnection procedure.

> 
> 
> One suggestion  is just to execute a 'SELECT 1;' to the database and see 
> if that results in a proper row (some timing issues might appear)
> doing a 'SELECT 1;' will also work for adodb connected databases.
> 

That might work... I'm not sure. I think there might be other reasons a 
query could fail...

> 
> Just come to think of it... doesn't mysql/php not have a keep alive 
> setting?? PostgreSQL has one.....

AFAIK, It doesn't. Things would be much simpler...

> 
> 
> 
> Ries
> 
> 
> On Aug 24, 2009, at 12:13 PM, Dan Osipov wrote:
> 
>> Thanks,
>> Attached is the CGL modified patch
>>
>> Dan Osipov
>> Calkins Media
>> http://danosipov.com/blog/
>>
>> Xavier Perseguers wrote:
>>> Hi,
>>> Dan Osipov wrote:
>>>> Attached is the updated patch that includes the DBAL implementation. 
>>>> Since nothing equivalent to mysql_ping exists in adodb, the function 
>>>> will return true for all other handlers.
>>> I'm OK with this solution as it is what I suggested in the mail I 
>>> sent you.
>>> However, I would like CGL to be applied (no tab before {, string 
>>> comparison with === instead of ==, boolean false as FALSE, just as 
>>> typed in comment)
>>> Regards
>> Index: t3lib/class.t3lib_db.php
>> ===================================================================
>> --- t3lib/class.t3lib_db.php    (revision 5810)
>> +++ t3lib/class.t3lib_db.php    (working copy)
>> @@ -981,6 +981,22 @@
>>     }
>>         return $ret;
>>     }
>> +   
>> +    /**
>> +    * Ping MySQL database to check if the connection is still alive. 
>> Reconnect if necessary
>> +    * mysql_ping() wrapper function
>> +    *
>> +    * @param    bool    TRUE if reconnect should be attempted
>> +    * @return    mixed    Either result of mysql_ping, or new 
>> connection ID if asked to reconnect.
>> +    */
>> +    function sql_ping($reconnect = FALSE) {
>> +        $pingResult = mysql_ping($this->link);
>> +        if (!$pingResult && $reconnect) {
>> +            return $this->sql_pconnect(TYPO3_db_host, 
>> TYPO3_db_username, TYPO3_db_password);
>> +        }
>> +       
>> +        return $pingResult;
>> +    }
>>
>>
>>
>> Index: typo3/sysext/dbal/class.ux_t3lib_db.php
>> ===================================================================
>> --- typo3/sysext/dbal/class.ux_t3lib_db.php    (revision 5810)
>> +++ typo3/sysext/dbal/class.ux_t3lib_db.php    (working copy)
>> @@ -1651,6 +1651,27 @@
>>     function sql_select_db($TYPO3_db)    {
>>         return TRUE;
>>     }
>> +   
>> +    /**
>> +    * Ping the database to check if the connection is still alive. 
>> Reconnect if necessary
>> +    * Only _DEFAULT handler is supported. Returns TRUE for other 
>> handlers
>> +    *
>> +    * @param    bool    TRUE if reconnect should be attempted
>> +    * @return    mixed    Either result of mysql_ping, or new 
>> connection ID if asked to reconnect.
>> +    */   
>> +    function sql_ping($reconnect = FALSE) {
>> +        if ($this->handlerCfg['_DEFAULT']['type'] === 'native')    {
>> +            $pingResult = mysql_ping($this->link);
>> +            if (!$pingResult && $reconnect) {
>> +                return $this->sql_pconnect(TYPO3_db_host, 
>> TYPO3_db_username, TYPO3_db_password);
>> +            }
>> +           
>> +            return $pingResult;
>> +        }
>> +        else {
>> +            return TRUE;
>> +        }
>> +    }
>>
>>
>>
>> @@ -1665,7 +1686,6 @@
>>
>>
>>
>> -
>>     /**************************************
>>     *
>>     * SQL admin functions
>> _______________________________________________
>> Before posting to this list, please have a look to the posting rules
>> on the following websites:
>>
>> http://typo3.org/teams/core/core-mailinglist-rules/
>> http://typo3.org/development/bug-fixing/diff-and-patch/
>> _______________________________________________
>> TYPO3-team-core mailing list
>> TYPO3-team-core at lists.netfielders.de
>> http://lists.netfielders.de/cgi-bin/mailman/listinfo/typo3-team-core
> 
> 
>             regards, Ries van Twisk
> 
> ------------------------------------------------------------------------------------------------- 
> 
> tags: Freelance TYPO3 Glassfish JasperReports JasperETL Flex Blaze-DS 
> WebORB PostgreSQL DB-Architect
> email: ries at vantwisk.nl        web:   http://www.rvantwisk.nl/    skype: 
> callto://r.vantwisk
> Phone: +1-810-476-4196    Cell: +593 9901 7694                   SIP: 
> +1-747-690-5133
> 
> 
> 
> 
> 
> 
>