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> -----Original Message-----
> From: Joshua Harlow [mailto:harlowja at outlook.com]
> Sent: Tuesday, June 16, 2015 4:52 PM
> To: OpenStack Development Mailing List (not for usage questions)
> Subject: Re: [openstack-dev] [taskflow] Returning information from reverted
> flow
> 
> Dulko, Michal wrote:
> >> -----Original Message-----
> >> From: Joshua Harlow [mailto:harlowja at outlook.com]
> >> Sent: Friday, June 12, 2015 5:49 PM
> >> To: OpenStack Development Mailing List (not for usage questions)
> >> Subject: Re: [openstack-dev] [taskflow] Returning information from
> >> reverted flow
> >>
> >> Dulko, Michal wrote:
> >>> Hi,
> >>>
> >>> In Cinder we had merged a complicated piece of code[1] to be able to
> >>> return something from flow that was reverted. Basically outside we
> >>> needed an information if volume was rescheduled or not. Right now
> >>> this is done by injecting information needed into exception thrown
> >>> from the flow. Another idea was to use notifications mechanism of
> TaskFlow.
> >>> Both ways are rather workarounds than real solutions.
> >> Unsure about notifications being a workaround (basically u are
> >> notifying to some other entities that rescheduling happened, which
> >> seems like exactly what it was made for) but I get the point ;)
> >
> > Please take a look at this review -
> https://review.openstack.org/#/c/185545/. Notifications cannot help if some
> further revert decision needs to be based on something that happened
> earlier.
> 
> That sounds like conditional reverting, which seems like it should be handled
> differently anyway, or am I misunderstanding something?

Current version of the patch takes another approach which I think handles it correctly. So you were probably right. :)

> 
> >>> I wonder if TaskFlow couldn't provide a mechanism to mark stored
> >>> element to not be removed when revert occurs. Or maybe another way
> >>> of returning something from reverted flow?
> >>>
> >>> Any thoughts/ideas?
> >> I have a couple, I'll make some paste(s) and see what people think,
> >>
> >> How would this look (as pseudo-code or other) to you, what would be
> >> your ideal, and maybe we can work from there (maybe u could do some
> >> paste(s) to and we can prototype it), just storing information that
> >> is returned from revert() somewhere? Or something else? There has
> >> been talk about task 'local storage' (or something like that/along
> >> those lines) that could also be used for this similar purpose.
> >
> > I think that the easiest idea from the perspective of an end user would be
> to save items returned from revert into flow engine's storage *and* do not
> remove it from storage when whole flow gets reverted. This is completely
> backward compatible, because currently revert doesn't return anything. And
> if revert has to record some information for further processing - this will also
> work.
> >
> 
> Ok, let me see what this looks like and maybe I can have a POC in the next
> few days, I don't think its impossible to do (obviously) and hopefully will be
> useful for this.

Great!
> 
> >>> [1] https://review.openstack.org/#/c/154920/
> >>>
> >>>
> >>
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