5:18 a.m.
----- Original Message -----
From: "Allon Mureinik" <amureini(a)redhat.com>
To: "Livnat Peer" <lpeer(a)redhat.com>
Cc: "Eli Mesika" <emesika(a)redhat.com>, "Liron Aravot"
<laravot(a)redhat.com>, "Federico Simoncelli"
<fsimonce(a)redhat.com>, "engine-devel" <engine-devel(a)ovirt.org>,
"Eduardo Warszawski" <ewarszaw(a)redhat.com>, "Yeela
Kaplan" <ykaplan(a)redhat.com>
Sent: Tuesday, August 14, 2012 2:10:55 PM
Subject: Re: [Engine-devel] Serial Execution of Async Tasks
Hi guys,
Thanks for all your comments!
The correct response for many these points is to update the wiki.
I'm enclosing here the quick-and-dirty replies just to keep this
thread alive, and will update the wiki shortly.
See inline.
----- Original Message -----
> From: "Livnat Peer" <lpeer(a)redhat.com>
> To: "Allon Mureinik" <amureini(a)redhat.com>
> Cc: "Eli Mesika" <emesika(a)redhat.com>, "Liron Aravot"
> <laravot(a)redhat.com>, "Federico Simoncelli"
> <fsimonce(a)redhat.com>, "engine-devel"
<engine-devel(a)ovirt.org>,
> "Eduardo Warszawski" <ewarszaw(a)redhat.com>, "Yeela
> Kaplan" <ykaplan(a)redhat.com>
> Sent: Sunday, August 12, 2012 9:39:23 AM
> Subject: Re: [Engine-devel] Serial Execution of Async Tasks
>
> On 10/08/12 03:40, Eli Mesika wrote:
> >
> >
> > ----- Original Message -----
> >> From: "Allon Mureinik" <amureini(a)redhat.com>
> >> To: "engine-devel" <engine-devel(a)ovirt.org>
> >> Cc: "Eduardo Warszawski" <ewarszaw(a)redhat.com>, "Yeela
Kaplan"
> >> <ykaplan(a)redhat.com>, "Federico Simoncelli"
> >> <fsimonce(a)redhat.com>, "Liron Aravot"
<laravot(a)redhat.com>
> >> Sent: Thursday, August 9, 2012 6:41:09 PM
> >> Subject: [Engine-devel] Serial Execution of Async Tasks
> >>
> >> Hi guys,
> >>
> >> As you may know the engine currently has the ability to fire an
> >> SPM
> >> task, and be asynchronously be "woken-up" when it ends.
> >> This is great, but we found the for the Live Storage Migration
> >> feature we need something a bit complex - the ability to have a
> >> series of async tasks in a single control flow.
> >>
> >> Here's my initial design for this, your comments and criticism
> >> would
> >> be welcome:
> >>
http://wiki.ovirt.org/wiki/Features/Serial_Execution_of_Asynchronous_Task...
> >
> > Apart from the short explanation & flow , since this is a
> > detailed
> > design , I would add
> > 1) Class diagram
> > 2) Flow diagram
Good idea, I'll see if I can jimmy something up.
> >
>
> +1, it would help understanding the flow.
>
> - It looks like you chose not re-use/extend the ExecutionHandler
> (the
> entity used for building the tasks view exposed to the users).
> It might be a good idea to keep the separation between the engine
> Jobs
> and the underlying vdsm tasks, but I want to make sure you are
> familiar
> with this mechanism and ruled it out with a reason. If this is the
> case
> please share why you decided not to use it.
As you said Jobs and Steps are pure engine entities - they can
contain no VDSM tasks, one VDSM task, or plausibly, in the future,
several tasks.
Even /today/, AsyncTasks and Jobs/Steps are two different kinds of
animals - I don't see any added value in mixing them together.
>
>
> - how does this design survives a jboss restart? Can you please a
> section in the wiki to explain that.
Basically, the way as a Command does today - the task is saved with
the executionIndex, and continues when the command is woken up.
I'll clarify this point in the wiki.
Added to the wiki.
>
> -successful execution -
> * "CommandBase iterates over its SPMAsyncTaskHandlers" - when?
This is the new suggested format of executeCommand(). I'll clarify
this too.
Added to the wiki.
> * If the second task is an HSM command (vs. SPM command), I
think
> you
> should explain in the design how to handle such flows as well.
HSM commands do not create AsyncTasks, as they do today - I will
clarify this.
Added to the wiki.
> * Why do we need before task? can you give a concrete example of
> what
> would you do in such a method.
Basically, /today/, command look like this:
executeCommand() {
doStuffInTheDB();
runVdsCommand(someCommand);
}
endSuccessfully() {
doMoreStuffInTheDB();
}
endWithFailure() {
doMoreStuffForFailureInTheDB();
}
In the new design, the entire doStuffInTheDB() should be moved to a
breforeTask of the (only) SPMAsyncTaskHandler.
>
> - I see you added SPMAsyncTaskHandler, any reason not to use
> SPMAsyncTasK to manage it own life-cycle?
Conserving today's design - The SPMAsyncTaskHandler is the place to
add additional, non-SPM, logic around the SPM task execution, like
CommandBase allows today.
>
> - In the life-cycle managed by the SPMAsyncTaskHandler there is a
> step
> 'createTask - how to create the async task' can you please
> elaborate
> what are the options.
new [any type of async task]
>
>
>
>
>
> Livnat
>
> >>
> >>
> >> -Allon
> >> _______________________________________________
> >> Engine-devel mailing list
> >> Engine-devel(a)ovirt.org
> >> http://lists.ovirt.org/mailman/listinfo/engine-devel
> >>
> > _______________________________________________
> > Engine-devel mailing list
> > Engine-devel(a)ovirt.org
> > http://lists.ovirt.org/mailman/listinfo/engine-devel
> >
>
>