[cairo] Solid pattern caching revisited

[Chris Wilson]

Behdad Esfahbod (behdad at behdad.org) said: 
[snip]
> That is all for now.  I think it would be natural for Chris Wilson,
> given his recent experience with the xlib screen stuff, to implement the
> xlib part and then porting Jorn's solid pattern cache to it will be
> trivial.

Ok, I prepared a branch that reimplements Jorn's cache on top of a
X11 workqueue and it is available for review under xlib-dpy-workqueue
[http://gitweb.freedesktop.org/?p=users/ickle/cairo;a=shortlog;h=xlib-dpy-workqueue].
I've checked that evince works for me but I welcome some feedback before
preparing a final version for inclusion.

The implementation is almost exactly as envisioned by Behdad with the
major complication arising with destroying X11 resources during
CloseDisplay. Something that is missing is reviewing the other backends
as to whether they too occasionally need to invalidate cached entries.
--
Chris Wilson