UDSEntry compression ideas

[Todd]

On Sep 17, 2013 12:58 AM, "Frank Reininghaus" <frank78ac at googlemail.com>
wrote:
>
> Hi Mark,
>
> I'm too tired for a longer reply already, but here is a quick idea
> that I just had and tried immediately.
>
> 2013/9/16 Mark:
> > Hi All,
> >
> > please read this as a brainstorm post with some ideas. I have no code
> > working in this area yet.
> >
> > Lazy loading is awesome, but if you can compress the data enough that
you
> > still have all details without lazy loading is even better i think. For
> > example, doing a directory listing on any given folder gives at least
the
> > following UDSEntry values:
> > - Device ID
> > - Inode
> > - User
> > - Group
> >
> > In the "experimental" case where you list the folder contents that has
just
> > a bunch of files created by one user you can say that at least the
above 4
> > properties are the same for all files. However, the experimental
situation
> > certainly doesn't work on "real data" where you can have files from
multiple
> > users and folders as well.
>
> Well, I guess that most people have quite a few folders where the
> "User" and "Group" are the same for all files ;-)
>
> The easiest "compression" that I could think of was to force the
> UDSEntries to implicitly share all their QStrings for one field if
> they are all equal:
>
> http://paste.kde.org/p52a24b49/
>
> Reduces the memory consumption in Details View for 100,000 items from
> 160.5 MB to 147 MB here. The patch is a bit hackish though, and it
> might have a small performance penalty. Maybe it's worth investigating
> that further though.
>
> I guess any more sophisticated "compression" approach will have to be
> implemented in frameworks only.
>
> Cheers,
> Frank

Do we need the UID and GID?  Can we just store whether the file is
readable, writable, and executable? That would be three bools rather than
two ints.
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