[packagekit] Caching of repository metadata (esp. Yum)

[Tim Lauridsen]

Jud Craft wrote:
> Hello there.  I wanted to make a criticism and suggest a change to
> GNOME-PackageKit's GUI frontend.
>
> (First of all, I'm still running Fedora 9, so perhaps in F10 and the
> new release this has been remedied).
>
> It is a significant aggravation to be unable to browse package lists
> using the Add/Remove software client whenever the packagekit daemon is
> already in the process of doing a system update, or already fetching
> lists for another task.
>
> And even when I have the daemon's full attention, the fact that it has
> to reload package information straight from the repository every time
> I select a new item is very annoying, especially since I may have just
> selected that same item a mere second ago.  It is doubling irritating
> when, due to internet connection irregularities, some items seem to
> load immediately, while others may take several seconds.
>
> Is there any way that packagekit could cache its own small database of
> package names and descriptions, thus removing the need to download
> fresh data for every single choice I make?
>
> I am aware of course that this is merely correcting a possible design
> flaw in Yum (that is, the flaw that Yum does not allow access to the
> package database whenever in the middle of another task).  But since
> Yum mainly just retrieves the information and handles the
> transactions, I think it would make sense if the backend that ran Yum
> then aggregated all the retrieved information on its own.
>
> It would be handy for, example, browsing the repository when not
> actually connected to the internet (especially if this could be
> combined with Yum's package cache feature, so that in fact, complete
> package browsing and reinstallation for recent packages could all be
> done offline, or at least with a minimum of duplicated network
> activity.)
>
> I'm not sure how well this would map to other PackageKit backends, but
> it would improve the experience greatly with Yum and Fedora.
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>   
There is mayor issues here.
It is by design that yum has a lock, so the yum metadata don't change 
while it is doing some action or strange things will happen.
rpm also has some locking, so multi processes can't do some actions cant 
be done in parallel.
This is safety matters, it is more important to keep your system 
consistent, than being able to do multiple actions  at once.
Another matter is the size of the metadata, my current yum metadata is 
296 M, it is a lot of data to cache and reload, it will add
another level of complexity.

Tim