Re: Apache::DBI connect

I only looked at Apache::DBI not DBI document.

My test program works. It reconnects to database OK. I ran it multiple times and every time it reconnects OK. But Apache::DBI doesn't work. You saw the previous debugging info. Where is the problem?

- xinhuan

From: Perrin Harkins <[email protected]<mailto:[email protected]>>
Date: Thursday, November 7, 2013 1:00 PM
To: Xinhuan Zheng <[email protected]<mailto:[email protected]>>
Cc: Adam Prime <[email protected]<mailto:[email protected]>>, "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>
Subject: Re: Apache::DBI connect

It is in the DBI documentation.  Search for "0E0".

- Perrin


On Thu, Nov 7, 2013 at 12:41 PM, Xinhuan Zheng <[email protected]<mailto:[email protected]>> wrote:
So it returns string '0E0'? The document didn't say that.

- xinhuan

On 11/7/13 11:44 AM, "Adam Prime" <[email protected]<mailto:[email protected]>> wrote:

>perl -e "if ('0E0') { print qq[hi\n] }"
>hi
>
>OE0 as a string evaluates to true.  If you use it as a bareword /
>numeric then it's false, which is what your eval example below is doing.
>
>Adam
>
>
>On 13-11-07 11:29 AM, Xinhuan Zheng wrote:
>> one correct - In both cases, the return value is evaluated to false.
>>
>> How do you distinguish?
>>
>> - xinhuan
>>
>> From: Xinhuan Zheng <[email protected]<mailto:[email protected]>
>> <mailto:[email protected]<mailto:[email protected]>>>
>> Date: Thursday, November 7, 2013 11:12 AM
>> To: Perrin Harkins <[email protected]<mailto:[email protected]> <mailto:[email protected]<mailto:[email protected]>>>
>> Cc: mod_perl list <[email protected]<mailto:[email protected]>
>><mailto:[email protected]<mailto:[email protected]>>>
>> Subject: Re: Apache::DBI connect
>>
>>> I don't actually understand why you did that.  What was wrong with the
>>>normal ping?
>>
>> With Oracle DRCP, even though ping succeeds, the connection to the
>> server process is actually terminated. Or ora_ping() may return 0E0
>> "zero but true" and undef. I don't know. ora_ping() is foreign to me. I
>> made the change based on what Apache::DBI the document said.
>>
>>> In any case, there's no need to change the Apache::DBI code, even with
>>>your "select 1 from dual" test.   It returns a true value (0E0) if it
>>>succeeds and a false value (undef) if it fails.
>>
>> In both cases, the return value is evaluated to true:
>>
>> 200: if ($Connected{$Idx} and (!$needping or
>>eval{$Connected{$Idx}->ping}))
>>
>> eval{0E0} and eval{undef} both return true. I did test that. How do you
>> distinguish?
>>
>>> Did your script succeed in reconnecting after it lost the connection?
>>
>> Yes.
>>
>>> Yes, I haven't forgotten about that, but I haven't had time to work on
>>>it yet.  You can try fixing it yourself by looking at the code in
>>>Apache::DBI that checks if the server is starting under apache 1.x.
>>>Otherwise, I will eventually get to it.
>>
>> I don't understand that piece of code. I can't do the change. Hope you
>> can help.
>>
>> - xinhuan
>>
>> From: Perrin Harkins <[email protected]<mailto:[email protected]> <mailto:[email protected]<mailto:[email protected]>>>
>> Date: Thursday, November 7, 2013 11:00 AM
>> To: Xinhuan Zheng <[email protected]<mailto:[email protected]>
>> <mailto:[email protected]<mailto:[email protected]>>>
>> Cc: mod_perl list <[email protected]<mailto:[email protected]>
>><mailto:[email protected]<mailto:[email protected]>>>
>> Subject: Re: Apache::DBI connect
>>
>> On Thu, Nov 7, 2013 at 9:46 AM, Xinhuan Zheng <[email protected]<mailto:[email protected]>
>> <mailto:[email protected]<mailto:[email protected]>>> wrote:
>>>The $ok is undef. In the case if the test does succeed (like the first
>>>select), $ok returns 0E0.
>>
>> That all sounds good.  0E0 is a true value in Perl.  It means "zero but
>> true."  And undef is a false value.  You don't need to test for undef.
>>
>>> Since I changed DBD::Oracle subroutine ping to use 'select 1 from
>>>dual',
>>
>> I don't actually understand why you did that.  What was wrong with the
>> normal ping?
>>
>> In any case, there's no need to change the Apache::DBI code, even with
>> your "select 1 from dual" test.  It returns a true value (0E0) if it
>> succeeds and a false value (undef) if it fails.
>>
>> Did your script succeed in reconnecting after it lost the connection?
>>
>>> I have another request. The Apache::DBI cached a dead database handle
>>>for apache version 1.3.42 if  startup.pl<http://startup.pl> <http://startup.pl> create a
>>>database handle. The apache
>> child processes inherits this dead handle. It doesn't cause application
>> error but it does take memory space. If there is many apache processes,
>> that's not good. Can you please identify and change the code for this
>> problem?
>>
>> Yes, I haven't forgotten about that, but I haven't had time to work on
>> it yet.  You can try fixing it yourself by looking at the code in
>> Apache::DBI that checks if the server is starting under apache 1.x.
>>   Otherwise, I will eventually get to it.
>>
>> - Perrin
>>
>