bug#41242: Port feature/native-comp to Windows - Reduce the number of files probed when finding a lisp file.

[Nicolas Bértolo]

> Isn't this a problem that should affect any Emacs on Windows?

You are right. I will open a separate bug.

Nico

El lun., 1 jun. 2020 a las 4:21, Andrea Corallo (<akrl@sdf.org>) escribió:
>
> Nicolas Bértolo <nicolasbertolo@gmail.com> writes:
>
> > Last night I came up with a fresh idea to properly solve the problem with 
> > slow
> > loads. Considering that it happens when `load-path` contains hundreds of
> > directories I thought that a caching mechanism would help.
> >
> > This "cache" would consist of a mapping of files that would get probed when
> > (load "foo") runs. It would be implemented as a hash table. This could get
> > stored in `package-user-dir` and package.el would be in charge of updating 
> > it
> > when installing or removing packages, just like autoloads.
> >
> > The contents of this hash table could be something like this:
> >
> > The directory company-20200525.101 could have a file load-cache.el with:
> >
> > company -> ("company-20200525.101/eln-hash/company.eln"
> >             "company-20200525.101/company.el"
> >             "company-20200525.101/company.elc")
> > [...]
> >
> > The directory helm-20200517.509 could have a file load-cache.el with:
> >
> > helm -> ("helm-20200517.509/eln-hash/helm.eln"
> >          "helm-20200517.509/helm.el"
> >          "helm-20200517.509/helm.elc")
> > [...]
> >
> > When `load-path` changes we could update the in-memory hash table by 
> > loading all
> > the load-cache.el files.
> >
> > Then, when (require 'foo) runs, the loading code could look at the hash
> > table and only fopen() the files associated with the feature we are loading.
> > This would reduce the number of calls to fopen() from thousands to ~3 in the
> > worst case.
> >
> > Of course, this feature would be disabled by default.
> >
> > What do you think?
>
> Hi Nico,
>
> could you recall me why this is specific to the native-comp branch?
> Isn't this a problem that should affect any Emacs on Windows?
>
> Thanks
>
>   Andrea
>
> --
> akrl@sdf.org