Re: Emacs design and architecture. How about copy-on-write?

[Ihor Radchenko]

Po Lu <luangruo@yahoo.com> writes:

>> Then try leaning on C-n or C-p _after_ everything is already
>> fontified.  You will still see that Emacs sometimes cannot keep up,
>> especially if lines are not too short.
>
> Long lines are, at worst, infrequently encountered in source code,
> aren't they?  And our troubles with long lines are an algorithmic
> impediment, which cannot be ameliorated merely by redisplaying each
> window on a different CPU.

I think that there is at least one way to address long lines using
asynchronous redisplay - put a placeholder on the problematic line and
continue calculating the actual rendering in the background instead.
That will not force us to compromise between rendering time and
accuracy, as we do now, with long-line-threshold.

Similar approach might be used to render mode lines - render a
placeholder until it is fully calculated, keeping Emacs responsive.

This idea is also relevant to a situation when asynchronous threads
"locks" a buffer whose window is visible. If a user tries to switch to
such buffer, it would be nice if Emacs does not hang until the lock is
released.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
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