[Engine-devel] Serial Execution of Async Tasks

[Yair Zaslavsky]

----- Original Message -----
From: "Eli Mesika" <emesika at redhat.com>
To: "Allon Mureinik" <amureini at redhat.com>
Cc: "Liron Aravot" <laravot at redhat.com>, "Federico Simoncelli" <fsimonce at redhat.com>, "engine-devel" <engine-devel at ovirt.org>, "Eduardo Warszawski" <ewarszaw at redhat.com>, "Yeela Kaplan" <ykaplan at redhat.com>
Sent: Friday, August 10, 2012 3:40:48 AM
Subject: Re: [Engine-devel] Serial Execution of Async Tasks



----- Original Message -----
> From: "Allon Mureinik" <amureini at redhat.com>
> To: "engine-devel" <engine-devel at ovirt.org>
> Cc: "Eduardo Warszawski" <ewarszaw at redhat.com>, "Yeela Kaplan" <ykaplan at redhat.com>, "Federico Simoncelli"
> <fsimonce at redhat.com>, "Liron Aravot" <laravot at 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_Tasks_Detailed_Design

Apart from the short explanation & flow , since this is a detailed design , I would add
1) Class diagram
2) Flow diagram 

+1
I am also interested to get a flow how a task is created (i.e - replacement of ConcreateCreateTask) - but this will be handled in what Eli has asked for.

In addition, you have two titles of  "Successful Execution".
At "compensate" - see how revertTasks currently behaves.
Also read -
http://wiki.ovirt.org/wiki/Main_Page/features/RunningCommandsOnEndActionFailure

This is the work I did for CloneVmFromSnapshot - not saying it's perfect - but you should have an infrastructure/pattern to rollback not just via spmRevertTask but also using an engine command.

Yair



> 
> 
> -Allon
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