[Mono-dev] SqlConnection.Open - debugging for beginners? Advice Welcome!

[Leszek Ciesielski]

This: http://www.mono-project.com/Parallel_Mono_Environments is not
entirely up-to-date, but the mono-dev-env script there is very useful.
You can configure your git clone with ./autogen --prefix=/opt/mono (or
even --prefix=~/mono , so that root is not required at any stage) and
use it in parallel with your system, without any change to the one
installed with your package manager.

On Mon, Apr 30, 2012 at 9:02 PM, Rob Wilkens <robwilkens at gmail.com> wrote:
>
> I had a peak inside the System.Data.SqlClient.SqlConnection.Open source code
> in mono, I did _not_ have time to look extensively.  What i did notice that
> may be suspect, without finding precise details, is that connection pooling
> -may- be going on in there.  That is: the first time it fails to connect, it
> may be adding a connection to the 'pool', and somehow it may not be removing
> that connection from the pool when the login fails, and next time it tried
> to connect, it used a failed connection from the pool somehow (A connection
> which never was established) and under certain conditions this results in a
> failure.  This is a guess and only based on a quick glance at the code, and
> not from debugging.
>
> If i'm going to debug this myself....
> What i need to do next, is refresh my memory on how to dump debug info to
> the console (i need the mono equivalent of a printf in c - i'm a fan of
> printf style debugging, i think there was a Console.out or something like
> that for my purposes that would work), plus figure out how to install a
> compiled mono installation to /usr/local (i've built it without installing
> it in a virtualbox virtual machine so i don't mess with my live
> installation).  I presume installing it to /usr/local will allow me to test
> without replacing any other mono that may be installed via packages, and
> also allow me to remove it from /usr/local to return to the packaged mono
> install somehow (again, it's a virtual machine set up just for this purpose,
> if it fails it's not the end of the world for me).
>
> I'm not sure when I'll get to this.  It's not that i'm busy, i just have a
> short attention span.  I spent most of my time so far setting up the
> VirtualBox installation so i could play in a sandbox, less time has been
> spent browsing the code.
>
> If anyone wants to chime in with a 'don't debug this yourself, let the
> experts do it' - please say so.  But i don't think i'm doing any harm
> playing with a local copy of the source which is all i have access to.
>
> -Rob
>
> ________________________________
> From: Rob Wilkens <robwilkens at gmail.com>
> To: mono-devel-list at lists.ximian.com
> Sent: Friday, April 27, 2012 2:57 PM
> Subject: [Mono-dev] System.Data.SqlConnection fails on 2nd invalid login
> attempt
>
> I probably shouldn't cross-post, but i wasn't sure where to put this, or if
> i should file a bug report (I'm new-ish to mono).  After reading the mailing
> list description, this seemed like a more appropriate place to ask.
>
> First, let me say this is not a critical problem, and i'm not sure whether
> it is a bug on mono or not.  I might be interested in trying to fix this
> myself if i can figure out where to start (later), just as a time waster
> project.
>
> When I create an SqlConnection called, say, MyConnection, and then call
> MyConnection.Open() - the second time i call it (though the first time with
> each new object it is called on) with an invalid login name/password, it
> fails with what appears to be an exception message that implies something
> was null when it shouldn't have been (object reference not set to instance
> of an object).  If i call it with a valid login name/password on any
> attempt, it doesn't raise any errors, as is expected.
>
> From what i can tell, this is happening inside of MyConnection.Open() ...
> and not in my code.  I've verified that MyConnection is not null when i call
> Open().
>
> If you want to see sample code, i'll point you to my other post on this
> topic:
> http://stackoverflow.com/questions/10355669/using-system-data-sqlconnection-in-mono-second-invalid-login-attempt-results-in
>
> Does this sound like something i should file a bug on?  Also, if i'm
> interested in contributing, would it be wisest to file a bug first, then
> attempt to resolve it?
>
> -Rob
>
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