Trash spec: caching the size of the trash directory

[David Faure]

On Wednesday 19 August 2009, Alexander Larsson wrote:
> On Thu, 2009-08-13 at 22:17 +0200, David Faure wrote:
> > And then it's up to implementations to update that value, when
> > adding a file to the trash, restoring a trashed file, deleting a trashed
> > file, and when emptying the trash.
> >
> > Is this OK with other implementors of the trash spec? Can it be added
> > to the spec?
>
> I'm a bit concerned about the performance costs of this. It means that
> you need to do a deep recursion into a folder counting its size when it
> is trashed. Whereas otherwise trashing a large folder structure is O(1)
> it now becomed O(number of files) and does a lot more I/O.

Correct. However the alternative (in order to implement a max size of the 
trash) is that every operation that puts a new file into the trash is O(number 
of files in the trash), which is clearly a lot worse!

Do you agree that the feature "maximum size of the trash" is useful?
I know many users who do ;-). Yes, even at the expense of a bit of performance 
(especially if the size-counting can be done without blocking the user 
interface, as is the case for us since the actual trash operations are handled 
in the kioslave which is a separate process; I think it's similar in gio?).

-- 
David Faure, faure at kde.org, sponsored by Qt Software @ Nokia to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).