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.
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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