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From Xinhuan Zheng <xzh...@christianbook.com>
Subject Re: Apache::DBI connect
Date Thu, 07 Nov 2013 16:29:29 GMT
one correct - In both cases, the return value is evaluated to false.

How do you distinguish?

- xinhuan

From: Xinhuan Zheng <xzheng@christianbook.com<mailto:xzheng@christianbook.com>>
Date: Thursday, November 7, 2013 11:12 AM
To: Perrin Harkins <pharkins@gmail.com<mailto:pharkins@gmail.com>>
Cc: mod_perl list <modperl@perl.apache.org<mailto:modperl@perl.apache.org>>
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 <pharkins@gmail.com<mailto:pharkins@gmail.com>>
Date: Thursday, November 7, 2013 11:00 AM
To: Xinhuan Zheng <xzheng@christianbook.com<mailto:xzheng@christianbook.com>>
Cc: mod_perl list <modperl@perl.apache.org<mailto:modperl@perl.apache.org>>
Subject: Re: Apache::DBI connect

On Thu, Nov 7, 2013 at 9:46 AM, Xinhuan Zheng <xzheng@christianbook.com<mailto:xzheng@christianbook.com>>
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> 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


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