Re: auto-update of Info dir file?

[David Kastrup <dak@gnu.org>]

Miles Bader <miles.bader@necel.com> writes:

> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> I think this will slow down Info startup to an intolerable degree.
>>> For example, I have more than 70 such top-level Info files in my Info
>>> directory, some of them compressed.
>>
>> It's probably OK if we only do the check when the mtime of the parent dir is
>> more recent than the mtime of the dir file (and only under Unix, of course,
>> since this presumes POSIXy semantics).
>
> I don't understand why Drew's suggestion would be slow anyway -- it's a
> simple syntactic check, which would only use the _names_ of the info
> files in the directory listing.  It wouldn't even have to stat the info
> files, much less read or decompress them.

Depends on how the stuff is done.  One can easily make an O(n^2) or
worse algorithm for this kind of thing.  Probably the fastest way
would be to stuff all menu entries and then files unsorted into one
list, sort that list (with `sort' which is stable), and then go
through it once, entering all files into the menu which are not
immediately preceded by a menu entry in the list.

This would probably be faster and use less memory than using a hash.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum