[ovirt-devel] Sortable Ui Columns

Alexander Wels awels at redhat.com
Mon Jun 2 15:22:45 UTC 2014 

On Monday, June 02, 2014 10:46:08 AM Vojtech Szocs wrote:
> ----- Original Message -----
> 
> > From: "Vojtech Szocs" <vszocs at redhat.com>
> > To: awels at redhat.com
> > Cc: devel at ovirt.org
> > Sent: Monday, June 2, 2014 4:37:27 PM
> > Subject: Re: [ovirt-devel] Sortable Ui Columns
> > 
> > 
> > ----- Original Message -----
> > 
> > > From: "Alexander Wels" <awels at redhat.com>
> > > To: "Lior Vernia" <lvernia at redhat.com>
> > > Cc: devel at ovirt.org
> > > Sent: Monday, June 2, 2014 3:35:51 PM
> > > Subject: Re: [ovirt-devel] Sortable Ui Columns
> > > 
> > > On Monday, June 02, 2014 11:27:26 AM Lior Vernia wrote:
> > > > After discussing this with Alex on another thread, I just pushed this:
> > > > http://gerrit.ovirt.org/#/c/28268/
> > > > 
> > > > If it's approved, then it'll take care of the secondary criterion for
> > > > you, so you only need to pass the criterion that actually interests
> > > > you.
> > > > Should simplify our work in the next couple of weeks.
> > > 
> > > Okay, I think we need to get everyone on the same page with this, right
> > > now
> > > we
> > > have several solutions to the problem, and I think we should pick one
> > > and
> > > go
> > > with that. Right now we have the following solutions available:
> > > 
> > > 1. Attempt to keep the current order in case of 'duplication' in the
> > > comparator. So the fallback is to keep the current order. This is
> > > implemented
> > > in Liors patch [1].
> > > 2. Use the hash code as a fallback in case of 'duplication' in the
> > > comparator.
> > > Due to hashcode rules this should result in the 'natural' order in case
> > > of
> > > duplicates. This is implemented in my patch [2].
> > > 3. Do ad-hoc fallback mechanism which can specialize to do the proper
> > > thing
> > > based on domain knowledge. It looks like this is what Anmol is doing in
> > > his
> > > gluster sorting patch [3]
> > > 4. Replace the SortedSet with a List but lose the ability to
> > > automatically
> > > sort when calling getItems().add(X).
> > > 
> > > To me it seems that 3 and 4 are off the table as we want to keep the
> > > ability
> > > to
> > > automatically sort. And doing ad hoc solutions for every single sorting
> > > column
> > > is going to take a lot of time and is going to lead to maintainability
> > > issues
> > > down the road. That leaves 1 and 2 on which I would like to have a
> > > discussion,
> > > so we can pick the appropriate method and go forward with that.
> > 
> > I just reviewed Lior's patch and posted some comments:
> >   http://gerrit.ovirt.org/#/c/28268/2/frontend/webadmin/modules/uicommonwe
> >   b/src/main/java/org/ovirt/engine/ui/uicommonweb/models/SortedListModel.j
> >   ava> 
> > Initially, I thought that computing item positions based on the order
> > in which they are returned by Collection's iterator might be unreliable,
> > now that I think more about it, I think this approach is something we
> > should consider.
> > 
> > In other words, in edge case when comparing two items with same logical
> > property (i.e. two Data Centers with same name), we should honor the
> > ordering of items within the original Collection provided by the server.
> > Otherwise, comparing hashCode might change their order in such edge
> > case. So actually it seems better to preserve Collection's iteration
> > order rather than preserving natural order in such edge case.
> 
> Just wanted to mention one more idea I just realized while talking with
> Alex: after we move to REST API, there won't be any hashCode anymore.
> We'll receive a collection (array) of items (objects) with IDs, which
> means hashCode will become backend business entity impl. detail. This
> is also the reason why I'm more inclined towards preserving order of
> items within original collection; there won't be any "natural ordering"
> of items after we move to REST API.
> 

Thinking about Liors patch a little bit doesn't it have the same problem as 
just replacing the sorted set with a list that we sort? doing 
getItems().add(item) will cause the sorting to no longer work, as that new 
item won't be in the positions map. So essentially this doesn't work any 
better than replacing the SortedSet with some sort of List.

> > What do you think guys?
> > 
> > > [1] http://gerrit.ovirt.org/#/c/28268/
> > > 
> > > [2] http://gerrit.ovirt.org/#/c/28225/
> > > 
> > > [3] http://gerrit.ovirt.org/#/c/28233/
> > > 
> > > > On 31/05/14 15:35, Anmol Babu wrote:
> > > > > Thanks a lot Alexander.Your idea of having a second criteria based
> > > > > sorting
> > > > > just in case of comparing same values(compare returning 0) looks
> > > > > good
> > > > > to
> > > > > me and now, I have also done the same in my patch set
> > > > > http://gerrit.ovirt.org/#/c/28233/.I have added you as a reviewer as
> > > > > well. Thanks,
> > > > > Anmol
> > > > > 
> > > > > ----- Original Message -----
> > > > > From: "Alexander Wels" <awels at redhat.com>
> > > > > To: devel at ovirt.org
> > > > > Cc: "Anmol Babu" <anbabu at redhat.com>
> > > > > Sent: Friday, May 30, 2014 5:55:20 PM
> > > > > Subject: Re: [ovirt-devel] Sortable Ui Columns
> > > > > 
> > > > > Anmol,
> > > > > 
> > > > > This is due to the fact that the sorting is done by a SortedSet
> > > > > instead
> > > > > of
> > > > > a list in the SortedListModel. To fix this we have to do one of two
> > > > > things:
> > > > > 
> > > > > 1. Change the sorting to use a list of some sort, but apparently
> > > > > that
> > > > > is
> > > > > not much of an option as people want automatic sorting when they add
> > > > > new
> > > > > items to the collection.
> > > > > 2. Make sure that the comparator never returns 0 for two entities
> > > > > that
> > > > > are
> > > > > really not the same. The reason you are seeing the issue is because
> > > > > you
> > > > > are
> > > > > using a different comparator that does return 0 on whatever field
> > > > > you
> > > > > are
> > > > > comparing against. I had the exact same issue and I solved it by
> > > > > using
> > > > > a
> > > > > compound comparator. Basically what I did was create a comparator
> > > > > that
> > > > > contains the field I am trying to compare on and if that returns 0
> > > > > then
> > > > > I
> > > > > use a different comparator that is guaranteed to not return 0 for
> > > > > the
> > > > > entity.
> > > > > 
> > > > > I have a patch that implements sorting for all the data center main
> > > > > tab
> > > > > and
> > > > > sub tabs here [1] that demonstrates how I solved the issue. This
> > > > > patch
> > > > > hasn't been reviewed yet, and my solution might get rejected, but it
> > > > > does
> > > > > work and doesn't make your entries disappear when you sort.
> > > > > 
> > > > > 
> > > > > [1] http://gerrit.ovirt.org/#/c/28225/
> > > > > 
> > > > > On Friday, May 30, 2014 02:32:17 AM Anmol Babu wrote:
> > > > >> Hi,
> > > > >> 
> > > > >>    While applying client-side sort using the sorting infra, to the
> > > > >>    "Server"
> > > > >> 
> > > > >> column of the "Volumes" sub tab "Bricks", I had 2 Bricks with same
> > > > >> server
> > > > >> name.So,when I sorted it, it removed one of the bricks that had the
> > > > >> same
> > > > >> server name. I found that this issue occurs when the sort values
> > > > >> compared
> > > > >> are same(i.e, comparator's compare returns 0). Regards,
> > > > >> Anmol.B
> > > > >> _______________________________________________
> > > > >> Devel mailing list
> > > > >> Devel at ovirt.org
> > > > >> http://lists.ovirt.org/mailman/listinfo/devel
> > > > > 
> > > > > _______________________________________________
> > > > > Devel mailing list
> > > > > Devel at ovirt.org
> > > > > http://lists.ovirt.org/mailman/listinfo/devel
> > > 
> > > _______________________________________________
> > > Devel mailing list
> > > Devel at ovirt.org
> > > http://lists.ovirt.org/mailman/listinfo/devel
> > 
> > _______________________________________________
> > Devel mailing list
> > Devel at ovirt.org
> > http://lists.ovirt.org/mailman/listinfo/devel

More information about the Devel mailing list