[ovirt-devel] [vdsm] VmDevices rework

[Dan Kenigsberg]

On Tue, Apr 28, 2015 at 04:28:12AM -0400, Martin Polednik wrote:
> Hello everyone,
> 
> I have started working on line of patches that deal with current state of VM devices
> in VDSM. There is a wiki page at [1] describing the issues, phases and final goals
> for this work. Additionally, there is formal naming system for code related to
> devices. I would love to hear your opinions and comments about this effort!
> (and please note that this is very long term work)
> 
> [1] http://www.ovirt.org/Feature/VmDevices_rework

Hi Martin,

It's a great and just initiative. Renaming is good, but I'd like to hear
more about your final goal - besides the hope that it the code is
shorter.

In my opion you should state your high-level goal explicitly:
device_object should be self-sufficient regarding: initiation, state
change, stat extraction and stat reporting.

Comments:
1. We want to drop the legacy conf support. In
   https://gerrit.ovirt.org/40104 we have removed support of engine<3.3
   so production environment does not need it any more.

   There might be an issue with command-line test scripts, though that
   might be abusing the legacy args. At the very least it should be
   marked as deprecated.

2. dev_map is an unfortunate historical mistake. The fact that it is a
   map of device type to device_object lists helps no one. It
   should be hidden behind one or two lookup functions. Each object
   class should be able to iterate its instances, and add filtering on
   top of that.

3. A definition like "Type of the device is dev_type" does not help for
   someone who knows what is dev_type. Please give examples.
   The "formal naming system" could use some wiki styling.

4. I did not understand "Libvirt XML parsing and processing is dumb -
   missing orchestration object to delegate XML chunks to devices themself"

5. It seems that you have further "phases" planned, but not written.
   Could you provide at least the title, or "charter" of each phase? 1.1
   is about renaming. 1.2 is about legacy. Do you have phases 2, 3..?

Death (or at least diet) to vm.py!

Dan.