Re: Proposal for Remote Execution

[Jürg Billeter <j bitron ch>]

On Wed, 2018-04-18 at 17:11 +0100, Jim MacArthur wrote:
> > Yes, the structure of the CAS artifact cache is very similar to the
> > OSTree artifact cache except that there are no commit objects, refs
> > directly point to Merkle tree hashes. I haven't implemented a purge
> > method yet but I'm not expecting any significant differences with
> > regards to cache expiration.
>
> If we're planning to use the Bazel method then there will be linked 
> objects in the CAS, e.g. build logs and build commands linked to a 
> particular build action, more things than just the build result which we 
> currently cache. We'll probably want to delete all the linked objects at 
> the same time, which might require some more thought.

This shouldn't change the logic of the WIP cache expiry methods,
though. The way OSTree prune works is that it deletes unreachable
objects. There is no need to keep Action and ActionResult messages and
their linked objects around for a long time, if the objects aren't also
reachable from a ref. Our CAS prune function will have to make sure to
avoid pruning objects from builds in progress. We yet have to define
the details for this, however, it should in any case not affect the
current WIP.

Jürg