Re: [Sqlgrey-users] PATCH: last_dbclean

[Lionel B. <lio...@bo...>]

Hi,

I'm back from my winter holidays. I initially liked your patch to
updateconfig because it seemed cleaner than what we discussed (at least
less complex) but then I realized there are 2 bugs. update_config
doesn't try to check for an $old_value if it is 0 which makes it
impossible to check for a successful update from a value expected to be
0. This is a corner case, but you can avoid it by using
(defined $old_value) ? ...
instead of
($old_value) ? ...
This is only a design problem with no actual consequence now but it's
safer to avoid any complication... Anyway the second bug is quite
serious and you'll have to remove the patch to update_config unless you
find another need for it...

Given that you only check for equality and not the timestamp being
expired at most only one SQLgrey instance will ever update the value and
then clean up (looking at the details, this will be the last instance
being launched). If this instance is shut down no other instance will
try to cleanup. You could even end with no cleanup occuring if the two
successive calls to time() give back two different values (your local
copy won't match the database), this could be fixed, but you can't avoid
the "cleanup" instance shuting down stops cleanup if you check for equality.

Conclusion : you can't use the config table, given that it only stores
varchars (you can't compare timestamps stored as varchars). You need to
create another table with only one stored value in a timestamp column
and check for expiration not equality.

Lionel.