Re: review of patch for Bug#25615, "Status command doesn't report anymore the Queries per second avg"

[Jocelyn Fournier]

Hi Chad,

Ok, I'll try to implement it through the use of double2decimal / 
decimal2string.
Just curious : what kind of OS / Debugger are you used to use inside MySQL ?
At work I'm using solaris 10 + workshop/sunstudio (dbx) on SPARC 
hardware which is fine, but at home I'm trying to use kubuntu + KDbg 
(gdb), and unfortunately I'm not happy with the result...

Thanks !
   Jocelyn

Chad MILLER a écrit :
> [add CC jimw]
> 
> On 20 Mar 2007, at 11:32, joce@stripped wrote:
>> I assume implementing %f is linked to WL#2934 ?
> 
> Hi Jocelyn.
> 
> No, I don't think there's a dependent relationship.  It would be nice to 
> have WL#2934 implemented, but clever use of mundane sprintf() could 
> solve this specific case well enough until it is.  We'll want to put a 
> note in that worklog to refactor my_snprintf() later.  We're obviously 
> not using "%f" in many places, and here it's not something that would 
> trigger the platform-specific variances in values.
> 
>> What's the status of the functions in decimal.c ?
>> (especially double2decimal and decimal2string)
> 
> Heh, I didn't know until I just now looked.   double2decimal() uses 
> sprintf(s, "%.16G", from) to get to a string, and then converts that 
> string to the internal decimal type.  That's somewhere we'll eventually 
> refactor when WL#2934 is implemented.  So, if you think you'd like to 
> use that, I imagine it's okay.
> 
> - chad
> 
> 
> 
>>>
>>>> --- sql_parse.cc.old    2007-03-03 17:53:15.000000000 +0100
>>>> +++ sql_parse.cc    2007-03-03 17:53:31.000000000 +0100
>>>> @@ -2119,7 +2119,7 @@
>>>>             &LOCK_status);
>>>>      calc_sum_of_all_status(&current_global_status_var);
>>>>      uptime= (ulong) (thd->start_time - start_time);
>>>> -    length= my_snprintf((char*) buff, buff_len - 1,
>>>> +    length= snprintf((char*) buff, buff_len - 1,
>>>>                          "Uptime: %lu  Threads: %d  Questions: %lu  "
>>>>                          "Slow queries: %lu  Opens: %lu  Flush
>>>> tables: %lu  "
>>>>                          "Open tables: %u  Queries per second avg:
>>>> %.3f",
>>>
>>>
>>> In addition to Sergei's comment that we should never use snprintf()
>>> outside the check for HAVE_SNPRINTF, the return value of snprintf()
>>> varies across implementations, so we should never even trust "length"
>>> in this case.  Thus, another reason we can't accept this approach.
>>> You're right, that adding floating-point decoding to my_snprintf() is
>>> the right approach.
>>>
>>> Jocelyn, are you comfortable implementing "%f"?
>>>
>>> - chad
> 
> 
> -- 
> Chad Miller, Software Developer                         chad@stripped
> MySQL Inc., www.mysql.com
> Orlando, Florida, USA                                13-20z,  UTC-0400
> Office: [phone]                         sip:6740@stripped
> 
>