[Dbix-class] Re: [Catalyst] Testcase for DBIx::Class::Loader - demonstrates failure under load

[Toby Corkindale]

On Mon, Feb 13, 2006 at 11:09:49AM -0600, Brandon Black wrote:
> On 2/13/06, Brandon Black <blblack at gmail.com> wrote:
> > On 2/13/06, Toby Corkindale <tjc at wintrmute.net> wrote:
> > > On Mon, Feb 13, 2006 at 09:55:31AM -0600, Brandon Black wrote:
> > > > Note that for DBIC/DBIC::Loader under Catalyst, I don't believe you need
> > > > Apache::DBI for persistent connections.  I believe as long as the model
> > > > instance stays alive, the connection is persistent anyways without it.  I
> > > > could be wrong, but I don't think so.
> > >
> > > Ah, cool. Yes, that appears to be the case.
> > >
> > > I wonder how that effects rollbacks at the end of processing (with and without
> > > Apache::DBI).
> > > I'll have to test that out sometime.
> > >
> >
> > It should have no ill effects for the "normal" DBIC case (like
> > C::M::DBIC::Plain / C::M::DBIC::Schema), the only ill effects will be
> > under DBIC ::Loader and ::Schema::Loader.  DBIC itself does
> > rollback-on-disconnect itself before calling the DBI disconnect
> > method, and it does this anytime the storage is being DESTROYed
> > (Apache::DBI kinda nullifies the actual disconnect, but the process is
> > dying anyways, so no biggie).
> >
> > The big ugly issue in this for the Loaders is that DBI.pm actually
> > looks for the presence of Apache/DBI.pm in %INC, and if so it sets a
> > *class* (or package if you prefer) variable $DBI::connect_via to
> > redirect its own connect/disconnect stuff through Apache::DBI.  The
> > whole DBI + Apache::DBI model of interaction is kinda flaky
> > considering the multiple apps under one mod_perl scenario.
> >
> > The cleanest answer is probably to, in your mod_perl configuration,
> > preload the Catalyst application module before you preload
> > Apache::DBI.  But we should probably handle the situation regardless
> > of load order.
> >
> > I've made the testcase work against Apache::DBI locally here, by
> > effectively storing up the old $DBI::connect_via, and overriding it
> > back to the "normal" DBI setting while Loader is doing its setup, then
> > restoring it after we're done.  I've thought through the implications
> > for other hypothetical Apache::DBI-using code sharing the same
> > mod_perl, and I don't think this is capable of causing them problems,
> > but I need to think some more before committing that.
> >
> > -- Brandon
> 
> Thought I'd move this over to the DBIC list. [ Toby are you on this
> list as well? ]

I am now :)

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