Re: [gentoo-portage-dev] [PATCH] portdbapi: Add cache to avoid repeated failing os.access calls

[Sebastian Luther]

Am 18.02.2014 22:35, schrieb David James:
>                     """
>     +               cache_key = (mycpv, mytree, myrepo)
>     +               try:
>     +                       return self._findname2_cache[cache_key]
>     +               except KeyError:
>     +                       self._findname2_cache[cache_key] = (None, 0)
>
>
> To me, it seems potentially error-prone to cache a (potentially)
> incorrect value and then correct it later.

It is. The problem are all these returns. The whole thing would need to
be reorganized to fix this. I'd rather go for a memoize decorator and
leave that thing alone. If I just could find a usable one.

Would it be possible to
> refactor your patch so that we only cache the value when we know the
> final answer?
>
>
>     +               except TypeError:
>
>
> In what circumstances does it happen that mytree / myrepo are unhashable
> types? Can you add a comment to explain this?

That's my mistake. I was under the impression that mytree is actually
mytreeS and would accept a list. I'll remove the "except TypeError:" in
a future version of the patch.