Re: [libvirt] [PATCH] qemuDomainRename: Report error if adding domain to domainObj list fails
On 15.08.2015 16:26, Martin Kletzander wrote:
On Fri, Aug 14, 2015 at 03:40:16PM +0200, Michal Privoznik wrote:
> So, domain renaming works like this: new domain name is added
> into the list of domain objects. Then, domain definition is
> updated. After that, old domain name is removed from the domain
> object list. Now, if the very firs step fails for some reason, no
Well, the problem here is that the first step can fail for 2 reasons.
One of them is that the domain already exists, the second one is an
OOM error. What's even worse is that the OOM error gets reported, but
the duplicate key error doesn't.
There should be either a hint for the user that domain with such name
already exists or that should be checked right before. The second
variant would not be race-free, but there would be only a small window
of opportunity left. The con would be that you won't report "already
exists" error when there's an OOM error already. Checking for that
error seems too weird, it would be more worth fixing the has table
implementation we have :)
Hm.. I agree that the partial error reporting is bad and definitely
calls for fixing. But I think it's gonna be tricky. I mean, we can't
emit a generic enough error message. "Duplicate key $key" would not be
much helpful for users since hash tables are used not only in
virDomainObjList. But maybe it would be better than nothing.
As a separate patch, we can reject the same name. Okay.
Michal