Subject: bug#78340: [PATCH] New option for comp *.eln file name by the file timestamp of *.el

From: Lin Sun <[email-masked]>
Date: Mon, 12 May 2025 16:38:06 +0000

From: Eli Zaretskii <[email-masked]>
Sent: Monday, May 12, 2025 02:24 PM
> ... which will probably be slow on Windows
> for the same reason computing the content hash is slow...

I want highlight reading a .el file will call windows api OpenFile/ReadFile.../CloseFile.
Here is an example that Emacs try to read the .el file to calculate the .eln name, it had called "ReadFile()" 6 time to read full content.
If Emacs uses timestamp, just call Getattribute() function, will reduce counts on windows file api calling.

"CreateFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","SUCCESS","Desired Access: Generic Read, Disposition: Open
"ReadFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","SUCCESS","Offset: 0, Length: 32,768, Priority: Normal"
"ReadFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","SUCCESS","Offset: 32,768, Length: 32,768"
"ReadFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","SUCCESS","Offset: 65,536, Length: 32,768"
"ReadFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","SUCCESS","Offset: 98,304, Length: 32,768"
"ReadFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","SUCCESS","Offset: 131,072, Length: 5,129"
"ReadFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","END OF FILE","Offset: 136,201, Length: 24,576"
"CloseFile","emacs-orig\lisp\emacs-lisp\byte-opt.el","SUCCESS",""
"CreateFile",".emacs.d\eln-cache\31.0.50-e92228c5\byte-opt-9c5f25f5-4dacc99e.eln","SUCCESS"