[Yum-devel] [PATCH] preload_from_sys also with --cacheonly, BZ 830523

[Zdenek Pavlas]

> --cacheonly
> With this option yum will work within it's cache directories only, so
> if it needs to download some extra data from the network it will fail.

>  I meant if someone leaves cachedir == system cache and sets cache=1.
>  I know there were a lot of small scripts that did that (before we had
>  setCacheDir()).

I see.. We'd fail with OSError on mkdir() instead of raising RepoError.
Would have to handle this when skip_if_unavailable=1, too.

> > a) revert 0f03409
> 
>  Doing this means that users are at the whims of root, if the system
> cache dir. isn't upto date with all the data they need available they
> are screwed (as they don't have permission to fix anything).

Users can always drop -C and have a writable cachedir, can't they?

> > b) system=>user preloading with --cacheonly.
> 
>  Right, that was on the plan and in your patches.
>  The only real downside here is that we need multiple copies of
> things ... but AFAICS having per. user caches is the only way to get
> it completely fixed.

Just stumbled on this:

    def doLock(...):
        if self.conf.uid != 0:
            #  If we are a user, assume we are using the root cache ... so don't
            # bother locking.
            if self.conf.cache:
                return

This not longer holds, and we preload/mkdir without locking..
That may be bad, but waiting  for a lock in completion-helper
isn't great either.. (though it's the user lock only).

>  cachedir=system
> 
> 1. Must use -C and make the repos. readonly, because we don't have
> permission to download or alter them anyway.
> 
> 2. Due to #1 if the cache isn't usable, we are just screwed.

The -C option is not mandatory.  If you are sure root's cache
is updated timely, use it.  Otherwise.. don't.