[cairo] invalid size error, nth ping

[Behdad Esfahbod]

Paolo Bonzini wrote:
> Commentary on my cache branch, as usual, would also be nice. :-)

I didn't look into it in detail, but from the glance I think the idea and API
was quite out of place.  Cairo's focus is in API usability.  Users should not
have to care about caching, let alone calling specific cairo API for it. Your
proposed API looked more suited to something like AGG, not cairo.

behdad