bug#41646: Startup in Windows is very slow when load-path contains many entries.

[Lars Ingebrigtsen]

Nicolas Bértolo <nicolasbertolo@gmail.com> writes:

>> Sorry, I meant 'access', of course.  More accurately,
>> GetFileAttributes.
>
> That was a very good idea. The attached patch reduces time spent
> in openp() during startup by 5 seconds, or 15%.

That's a huge speed-up indeed.

[...]

> -             fd = emacs_open (pfn, O_RDONLY, 0);
> +                /*  In some systems (like Windows) finding out if a
> +                    file exists is cheaper to do than actually opening
> +                    it.  Only open the file when we are sure that it
> +                    exists.  */
> +#ifdef WINDOWSNT
> +                if (faccessat (AT_FDCWD, pfn, R_OK, AT_EACCESS))
> +                  fd = -1;
> +                else
> +#endif
> +                  fd = emacs_open (pfn, O_RDONLY, 0);
> +

This is a Windows-specific patch, so I have no opinion on it.  Eli?
Does this make sense to you?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no