[katello-devel] Pre-save and post-save queues in glue layer

[Tomas Strachota]

On 01/26/2012 09:56 AM, Ivan Nečas wrote:
> Hi,
>
> After GPG keys orchestration, I'm working on another task where we need
> to do some action after saving a record to our database: we create
> environment in Katello and then in Candlepin (we are sending there our
> environment_id.
>
> Like it was pointed out before, in current state all the orchestration
> happens before the record is saved:
>
> def on_save
> process queue
> yield if block_given?
> @orchestration_for = nil
> end
>
> I suggest to rename our current queue to pre_queue (which means to
> happen before saving) and post_queue (after saving). So the on_save
> around filter would look like this:
>
> def on_save
> process pre_queue
> yield if block_given?
> process post_queue
> @orchestration_for = nil
> end
>
> I've already tested it in my branch, and it looks it serves our
> purposes. We don't have to worry about record being created before some
> orchestrations fails: on_save runs whole in transaction and when
> something is wrong, it rolls back the insertion. From my sql log after
> simulating an error after saving:
>
> SQL (6.7ms) INSERT INTO "providers" ("created_at", "updated_at",
> "organization_id", "provider_type", "repository_url", "name",
> "description") VALUES ('2012-01-26 08:52:44.664467', '2012-01-26
> 08:52:44.664467', 1, 'Custom', NULL, 'katello', NULL) RETURNING "id"
> SQL (0.1ms) ROLLBACK
>
>
> I would like to get some team ACK before actually implementing the whole
> change, incluiding renaming the original queue. Any suggestions on
> better naming etc. welcomed.
>
> -- Ivan
>

I like the idea of having two queues.
But one question: If the post_queue fails, are actions from pre_queue 
rollbacked as well?

Tomas