Re: Trying to track down bug in DBD::Multi

On 08/11/10 15:46, Jens Rehsack wrote:
> 2010/8/11 Dan<[email protected]>:
>> Hi,
>
> Hi Dan,
>
>> I received a bug report (#60193) regarding the following error with
>> DBD::Multi:
>>
>> DBD::Multi initialisation failed: invalid method name 'versions' at
>> /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/DBI/DBD/
>> SqlEngine.pm line 88
>> at t/dbd-multi-db.t line 10
>>
>>  From what I can tell, that "invalid method name" error originates from
>> DBI::install_method:
>>
>>         Carp::croak("invalid method name '$method'")
>>             unless $method =~ m/^([a-z]+_)\w+$/;
>>
>>  From what I can gather, DBI::DBD::SqlEngine is calling DBI-
>>> driver_prefix('DBD::multi'), getting back undef, concatenating that
>> undef with 'versions', and then making a call to
>> DBD::_::common::install_method('DBD::Multi::db', 'versions').   This
>> dying because the method name is lacking an underscore.
>
> No, it's dying because install_method allows only method names
> with valid driver prefixes. DBD::Multi isn't registered in
> $dbd_prefix_registry in DBI.pm, but it probably should be there ;)
>
> I'm sorry, I didn't recognize that DBD::Multi is derived from DBD::File,
> this is my fault, I should add a registry key for it.
>
>> Here's a call stack from the perl debugger right before it dies:
>>
>> . = DBD::_::common::install_method('DBD::Multi::db', 'versions')
>> called from file `/usr/local/lib/perl5/site_perl/5.10.1/i386-freebsd/
>> DBI/DBD/SqlEngine.pm' line 88
>> $ = DBI::DBD::SqlEngine::driver('DBD::Multi', ref(HASH)) called from
>> file `/usr/local/lib/perl5/site_perl/5.10.1/i386-freebsd/DBD/File.pm'
>> line 73
>> $ = DBD::File::driver('DBD::Multi', ref(HASH)) called from file `/usr/
>> local/lib/perl5/site_perl/5.10.1/DBD/Multi.pm' line 20
>> $ = DBD::Multi::driver('DBD::Multi', ref(HASH)) called from file `/usr/
>> local/lib/perl5/site_perl/5.10.1/i386-freebsd/DBI.pm' line 811
>> $ = eval {...} called from file `/usr/local/lib/perl5/site_perl/5.10.1/
>> i386-freebsd/DBI.pm' line 811
>> $ = DBI::install_driver('DBI', 'Multi') called from file `/usr/local/
>> lib/perl5/site_perl/5.10.1/i386-freebsd/DBI.pm' line 643
>> $ = DBI::connect('DBI', 'DBI:Multi:') called from file `t/dbd-multi-
>> dr.t' line 9
>>
>> This appears to be a chance in functionality of DBD::File that was
>> introduced in 1.611_90.   Prior to that, I don't think it attempted to
>> inject the versions method.
>>
>> So, I have two questions:
>>
>> 1.  Does my analysis seem correct?
>
> Mostly, especially the relevant parts.
>
>> 2.  Any suggestions on the best way to allow DBD::Multi to continue to
>> work with both older releases of DBI and also work with revisions>=
>> 1.612?
>
> I can do two fixes:
> 1) DBD::File can skip method injection when no prefix found
> 2) Add a registry key for DBD::Multi to DBI
>
> But this will keep you failing for DBI between 1.612 and 1.614.
>
> You can add following code to your DBD::Multi::db:
>
> if( DBI->version lt '1.614' ) {
>      *version = sub {};
>      *get_meta = sub {};
>      *set_meta = sub {};
>      *clear_meta = sub {};
> }
>
> This will lead DBD::File (and DBI::DBD::SqlEngine) to skip the
> method injection and installing.
>
> I fear, this won't be the only issues you will encounter when
> using old DBD::File based code with DBD::File>= 0.39.
> Probably you've recognized (I hope you are subscribed on this
> mailing-list) the issues Steffen had while porting DBD::PO to
> new DBD::File.
>
> But you do not need any of the features provided by DBD::File
> or DBI::DBD::SqlEngine - you can avoid deriving from both and
> derive directly from DBD::_::* by calling DBI->setup_driver
> somewhere in your DBD::Multi module.

I didn't read any response. Does it mean, the issue is solved from
our point of view or weren't my explanations not understandable?

/Jens