Re: [Engine-devel] Storing command parameters
----- Original Message -----
From: "Yair Zaslavsky" <yzaslavs(a)redhat.com>
To: "Eli Mesika" <emesika(a)redhat.com>
Cc: "Sahina Bose" <sabose(a)redhat.com>, "engine-devel"
<engine-devel(a)ovirt.org>
Sent: Sunday, September 8, 2013 10:55:48 AM
Subject: Re: [Engine-devel] Storing command parameters
----- Original Message -----
> From: "Eli Mesika" <emesika(a)redhat.com>
> To: "Sahina Bose" <sabose(a)redhat.com>
> Cc: "Yair Zaslavsky" <yzaslavs(a)redhat.com>,
"engine-devel"
> <engine-devel(a)ovirt.org>
> Sent: Sunday, September 8, 2013 10:44:43 AM
> Subject: Re: [Engine-devel] Storing command parameters
>
>
>
> ----- Original Message -----
> > From: "Sahina Bose" <sabose(a)redhat.com>
> > To: "Yair Zaslavsky" <yzaslavs(a)redhat.com>,
"engine-devel"
> > <engine-devel(a)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.
Sure, I just meant to see what is done there as a code sample
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.
So, since Gluster has there own async tasks , do you recommend to have a separate table
for their tasks ???
I think that they can use the current one , maybe we need additional column in async_tasks
to distinguish between Gluster & our tasks ...
Yair
>
>
> >
> > thanks
> > sahina
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> >
>