Re: What ostree operations are safe to do concurrently

[Colin Walters <walters verbum org>]

On Thu, Dec 3, 2015, at 12:26 PM, Alexander Larsson wrote:
> Well, that would fix the pull, but what about remove. I mean, we do
> want to support uninstall apps, and we call ostree_repo_prune with
> depth=0 on updates. This can break in-progress pulls at the very least.
> I can also imagine it breaking if you do a prune and update a ref
> halfway that things would break.

Ah, yes.  This case for "system" ostree is presently covered by the
`OstreeSysroot` lock. 

> Maybe I can have some kind of reader-writer lock that we take (for
> write) on uninstall to protect any ongoing pulls (they take a read
> lock). We could also skip the prune if any other operation is ongoing,
> as it will be run eventually anyway.

I'd be fine having it in `OstreeRepo` too.  It's presently not reader-writer,
doing that would need some sort of shared memory negotiation I think.