[Dbix-class] ROLLBACK seems to be skipped on 0.08

[Darren Duncan]

At 4:04 PM -0500 10/22/07, Brandon Black wrote:
>On 10/22/07, Darren Duncan <darren at darrenduncan.net> wrote:
>>  Muldis DB also has separate start|commit|rollback_trans() methods
>>  that the Perl application can invoke (but Muldis D stored routines
>>  can't) whose purpose is to support wider-scope parent-most
>>  transactions in the application where it isn't practical to put all
>>  parts of it into a stored routine, such as because interaction with
>>  non-database systems or users needs to be done between stages.
>>
>>  Based on my understanding, DBIx-Class' separate
>>  txn_begin|commit|rollback() routines correspond to this, assuming
>>  they aren't invoked by user code in a txn_do().
>>
>>  To summarize, I recommend for DBIx-Class an emphasis on txn_do() for
>>  any situation where it would work, which includes executing just
>>  single operations, and that autocommit=1 should be constant.  An
>>  autocommit=0 can be simulated by just having explicit
>>  begin/commit/rollback where appropriate.
>>
>
>I think ideally we'd like to deprecate and/or eliminate
>->txn_{begin,commit,rollback} as well, and basically stick users with
>AutoCommit=>1 and txn_do.  If we could find some concrete examples of
>sane things that can't be done with just txn_do, that would be a good
>reason to keep the others around, but I don't think such an example
>exists (if you know of one, please speak up).  txn_do closures and the
>magic of $self->next::can covers just about everything I can think of.

Using just txn_do() for everything in DBIx-Class may very well be 
feasible, more so than with using just call_proc() would be with 
Muldis DB, so you may be able to do the deprecation you mentioned.

A key difference I see is that the Muldis DB framework presents an 
isolated system (which is more effective for safety and portability). 
A Perl application can call Muldis D routines, but Muldis D routines 
can't call back out into the application environment (all closures 
within Muldis DB are also, from the users viewpoint, written in 
Muldis D rather than Perl).

As a result, since DBIx-Class' txn_do() can take an arbitrary Perl 
closure as input, it can conceivably do more, since Perl closures 
aren't so isolated.

In other words, I support your proposal.

-- Darren Duncan