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

[Ries van Twisk]

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...


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.....


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.


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



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
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			regards, Ries van Twisk

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