[Engine-devel] Storing command parameters

[Yair Zaslavsky]

----- Original Message -----
> From: "Eli Mesika" <emesika at redhat.com>
> To: "Sahina Bose" <sabose at redhat.com>
> Cc: "Yair Zaslavsky" <yzaslavs at redhat.com>, "engine-devel" <engine-devel at ovirt.org>
> Sent: Sunday, September 8, 2013 10:44:43 AM
> Subject: Re: [Engine-devel] Storing command parameters
> 
> 
> 
> ----- Original Message -----
> > From: "Sahina Bose" <sabose at redhat.com>
> > To: "Yair Zaslavsky" <yzaslavs at redhat.com>, "engine-devel"
> > <engine-devel at ovirt.org>
> > Sent: Tuesday, September 3, 2013 4:16:53 PM
> > Subject: [Engine-devel] Storing command parameters
> > 
> > Hi all,
> > 
> > As part of the gluster volume asynchronous tasks, we ran into a
> > requirement wherein when we start a command, we need to remember the
> > parameters that the command was started with.
> > 
> > Is there any infrastructure available to do this, or should we build
> > something?
> 
> Hi Sahina
> There is such a mechanism , it is called Compensation
> You can look at backend:compensate to see how it is used to rollback commands
> in the case of failure.
> 
> Yair can elaborate & help on that since he is the owner of this code

Eli, I think using compensation here is an abuse.
Compensation is used to take snapshots of entities, and snapshots only classes THAT ARE (a plural of the "IS A" inheritance rule :) ) business entities.
The closest thing we have today to what Sahina needs, is IMHO async_tasks table which have command_id and parameters stored.
However, storing command parameters at tasks table is somewhat awkward (yes, I know we're doing it until this very moment) and we should revisit this, and have a real
table to store commands and associated parameters.

Yair


> 
> 
> > 
> > thanks
> > sahina
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>