Re: [BuildStream] cache key changes

[Darius Makovsky <darius makovsky codethink co uk>]

On 05/07/2019 15:31, Jürg Billeter wrote:
> [...]
> Weak cache key dicts normally only contain the names of the
> dependencies, not their (weak) cache keys, otherwise the cache key of
> an element would change whenever the source of a dependency changes,
> which we want to avoid for non-strict builds.

You're right, 'key' is not the right term here but for homogeneity in
the treatment the term is applicable. I don't have a strong opinion
though. However, the as I understand it, the weak cache keys are always
calculated along with the strong ones. The proposal here is to replace
`dependencies` with two sets, one of strong keys and the other of weak
keys. When strictly building the strong keys will be used and for
non-strict builds the weak keys. I'm not sure there's value in adding a
third set of dependency names since I think to avoid unnecessary
rebuilds the keys would need to be calculated.

> [...]
> > * `environment` is replaced `environment-variables`
>
> The .bst format also uses `environment` for this. I'm not convinced
> we're reducing confusion by using different names in .bst and the cache
> key dict.

Agreed

> [...]
>
> `public-nocache` would be an addition to the .bst format.
> [...]
>
> I think it would be best to discuss this separately as it would be a
> format enhancement and would not affect the cache key. That discussion
> should include a description of possible use case(s) for `public-
> nocache`.

Yes, that should be a separate issue


-- 
Best Regards,
Darius


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