Re: AW: Re: Free images based on allocated memory

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 31 Jan 2019 18:33:28 +0100
> From: Andreas Politz <politza@hochschule-trier.de>
> Cc: emacs-devel@gnu.org
> 
> Yes, I know about image eviction delay.  Also, I'm not really sure if what I was proposing is a good idea.
> 
> One goal in my package is it to display PDF pages quickly. 
> There are 2 factors delaying this:  The actual rendering in the back-end (via poppler) and the loading of the
> image by Emacs.  
> 
> In order to limit this timespan, pages are speculative pre-rendered and pre-loaded. E.g. if page n is currently
> displayed, the user probably wants to view page n+1 next. This is implemented by filling  a LRU cache while
> Emacs is idle.
> 
> Note how this conflicts with a least-recently-displayed eviction strategy.
> 
> Of course this can be solved in Lisp, just not very elegantly.  I spare you the details.

Thanks for the explanations, but I'm not sure I understand: is the
patch you proposed intended to fix these issues?  If so, can elaborate
on how it fixes them?

> Another extension point, which would help managing the image-cache in my case, would be the ability to flush
> images based on their data.  Note, this is currenly only supported for file based images.

Doesn't image-flush fit this bill?  If not, can you tell why not?