KIO slaves: fuse moutned remote filesystems treated as local filesystems.

[David Faure]

On Monday 22 September 2014 08:34:48 Euan Thoms wrote:
> My question refers to KDE4 specifically, but may be relevant to KDE5 also.
> 
> I'm using WebDAV for our corporate roll-out via davfs2 (fuse module for
> WebDAV). In Dolphin the browsing can be very slow because of 2 things:
> 
> (i) the size column gets populated with number of items within (e.g.
> recursive listing). (ii) the use of mime magic to determine file type means
> that with davfs, the whole file is downloaded in order to read the first 10
> bytes or so. For a 100MB file, this is extremely inefficient.
> 
> Krusader has options that's allows you to turn off mim magic (and rely on
> file extensions alone), and it doesn't inspect the contents of sub-folders.
> The net result is much faster browsing through a davfs2 mounted
> filesystems.
> 
> However, Dolphin and KIO in general, is well integrated into KDE. Therefore
> I would like to firstly; hack kdelibs in 4.10.5 for my corporate rollout.

> Secondly; perhaps have an option in future versions of KDE4 /5 to disable
> these clever but inefficient features of KIO.
> 
> I noticed that when connecting to WebDAV using the webdav:// KIO slave, the
> folder size is replaced with "unknown". So how would I go about making the
> file:// KIO slave behave the same way?
> 
> I am browsing throught the kio code, however it is very so[phisticated and
> therefore complex codebase. So I would appreciate if someone would point me
> in the right direction.

In 6369b556ae9beef6888699d23b91326bac950ba4 (which you have in 4.10.5),
(followed by ee3823dea680f), icon name became a delayed operation, to help 
with slow mounts.

ChildCountRole in KDirModel doesn't do that, hence the problem you're seeing.

Solution: ideally, this should be done delayed too.
For instance by moving the feature to KFileItem so that it's also done delayed 
when m_delayedMimeTypes is true.


Problem (ii) is solved (well improved) in Qt5 where "magic determination"
only reads the first 16 KB of the file.

-- 
David Faure, faure at kde.org, http://www.davidfaure.fr
Working on KDE Frameworks 5