From bug-request at octave dot org Fri Apr 14 12:11:44 2006
Subject: Re: finding everything fast
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Tom Holroyd <tomh at kurage dot nimh dot nih dot gov>
Cc: bug at octave dot org
Date: Fri, 14 Apr 2006 13:11:21 -0400

On  8-Apr-2006, Tom Holroyd wrote:

| On Fri, 7 Apr 2006, Tom Holroyd (NIH/NIMH) [E] wrote:
| 
| > searching the entire LOADPATH, every time.

I think the code in kpse.cc that is supposed to handle caching of file
names in the path is not being used properly.

| I'm not sure what the intent is here, or where the code is, but I 
| guess there is always the possibility that sometimes, you will 
| want to search the entire path for a function, even if you 
| already know where it is.

Yes, I think Octave needs to do this to properly implement the
autoload-if-there-is-a-newer-version-somewhere-on-the-path semantics
of Matlab.  So it does need to search the path again to see if a newer
function has appeared.  But I agree that something is currently broken
as we should be able to cache the contents of directories and only
check the disk if it appears that a directory in the path has changed.
In any case, looking at the disk should only happen once per prompt,
not on every call to a function

| It would probably be a good idea 
| though, to have a feature that allowed such searching to be 
| turned off, for "production" installations where everything is 
| already installed right and you know that nothing is going to 
| change during a run.  Then it could just cache the locations of 
| all functions at startup time and be done with it.

I don't think this should be necessary if the check only happens
once per prompt and if caching of filenames on the path is working
correctly.

The path searching code used to depend on ls-R files (like those used
for TeX systems that use the kpathsearch library) but that turned out
to have its own problems.  I think the best thing to do is modify the
path searching code to construct an internal version of the ls-R
database incrementally as needed.  I don't think this is currently
happening.

jwe



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