Re: Tree-sitter api

[Eli Zaretskii]

> From: Yuan Fu <casouri@gmail.com>
> Date: Sat, 18 Dec 2021 18:51:25 -0800
> Cc: Philipp <p.stephani2@gmail.com>,
>  ubolonton@gmail.com,
>  theo@thornhill.no,
>  cpitclaudel@gmail.com,
>  emacs-devel@gnu.org,
>  monnier@iro.umontreal.ca,
>  stephen_leake@stephe-leake.org,
>  john@yates-sheets.org
> 
> >> That feature in itself won't be enough.  Even with it, TreeSitter will 
> >> have the same problem as GMP: allocation isn't allowed to fail, and 
> >> longjmp'ing out of it isn't allowed and generally causes undefined 
> >> behavior.
> > 
> > It may not be enough to satisfy purists, but it's enough to allow the
> > user to save the session and shut down Emacs in an orderly fashion,
> > instead of abruptly exiting and losing all the edits.
> 
> Uses can set tree-sitter-maximum-size to limit memory usage of tree-sitter. 
> Buffers with size larger than that cannot enable tree-sitter. That doesn’t 
> solve the problem directly but should let users avoid allocation failing most 
> of the time.

Btw, we should have a good idea how frequent this out-of-memory
problem could be with tree-sitter.  Did someone try to scroll through
all of xdisp.c, using tree-sitter for C Mode fontifications, and
measured the memory footprint that produces?  If not, I think it would
be a good idea to try.

If the OOM problem happens frequently with large source files, it may
indeed be the case that we will need to disable tree-sitter up front
based on some size criteria.