[PATCH 0/1 conductor] BZ 784499 add check to ensure task exists before saving
Jan Provaznik
jprovazn at redhat.com
Fri Feb 3 20:43:48 UTC 2012
On 02/03/2012 04:09 PM, Tzu-Mainn Chen wrote:
> Here's the original situation:
>
> begin
> .
> .
> .
> task.instance.state = dcloud_to_instance_state(dcloud_instance.state)
> task.instance.save!
> task.state = Task::STATE_FINISHED
> rescue Exception => ex
> task.state = Task::STATE_FAILED
> task.message = ex.message
> ensure
> task.save!
> end
>
> Due to optimistic locking, the above code gives stale object exceptions if the task is successfully deleted. My understanding is that this is because the after_save method in instance_observer.rb will (under certain circumstances), delete itself and its tasks, meaning task.save! will fail.
>
> The patch replaces
>
> task.save!
>
> with
> task.save! if Task.exists?(task.id)
>
> If there's a better way to handle this (or if my logic is wrong), please let me know!
>
>
> Mainn
>
ACK
BTW, I'm surprised by behaviour of "dcloud_instance.send(action)" - I
thought that it's async call, but it updates dcloud_instance.state directly.
Then it's possible that an instance's state is changed to 'stopped'
right after "dcloud_instance.send" call.And if it's last instance in a
deployment, the deployment is destroyed (with instances).
Jan
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