[Tcl-bugs] [ tcl-Feature Requests-680169 ] Tcl interpreter pkgIndex 'cache'

[SourceForge.net <no...@so...>]

Feature Requests item #680169, was opened at 2003-02-04 05:29
Message generated for change (Comment added) made by jenglish
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=360894&aid=680169&group_id=10894

Category: 38. Package Manager
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Larry W. Virden (lvirden)
Assigned to: Don Porter (dgp)
Summary: Tcl interpreter pkgIndex 'cache'

Initial Comment:
 A feature I believe would be useful is a master
package index cache that would be updated each time a
package was installed into a subtree.

If the cache were present, it would be, by default, the
only place searched for a package's presence (though
this could be overridden by an application if so desired).

This would reduce the startup time of a tcl
interpreter, which in a general case can be quite
lengthy if a site has 50 or more extensions installed.

----------------------------------------------------------------------

>Comment By: Joe English (jenglish)
Date: 2003-10-21 14:06

Message:
Logged In: YES 
user_id=68433

Attached tcl-pkgcache.patch is an alternate approach (which
I've been using for several months now locally).  I believe
this is the minimum necessary and sufficient change to
init.tcl:

+    if {[info library] != ""} {
+       variable pkgCache [file join [info library]
pkgCache.tcl]
+       if {[file exists $pkgCache]} { 
+           source $pkgCache
+       }
+    }

This just sources the file $tcl_library/pkgCache.tcl on
startup, if it exists.  Generating and maintaining the
package cache is left up to local administrative policies.

----------------------------------------------------------------------

Comment By: Nobody/Anonymous (nobody)
Date: 2003-07-10 22:20

Message:
Logged In: NO 

Works *much* better now; my 5+ second delay before getting a
prompt is now gont!

Script started on Thu Jul 10 23:55:48 2003
sh$ time tclsh
exit
% exit

real    0m5.556s
user    0m1.587s
sys     0m1.318s

sh$
sh$ # After patch to init.tcl
sh$

sh$ time tclsh
exit
% exit

real    0m6.073s
user    0m0.757s
sys     0m1.368s

sh$ # The .tclPackageIndexCache was created
sh$
sh$ time tclsh
exit
% exit

real    0m0.750s
user    0m0.287s
sys     0m1.124s
sh$ exit
Script done on Fri Jul 11 00:03:10 2003

Dave Bodenstab <im...@mi...>

----------------------------------------------------------------------

Comment By: Don Porter (dgp)
Date: 2003-03-04 12:38

Message:
Logged In: YES 
user_id=80530

FWIW, the caches should probably
also be per-[package unknown] so
that caches of one unknown handler
don't interrupt a different one.

----------------------------------------------------------------------

Comment By: Don Porter (dgp)
Date: 2003-03-04 12:35

Message:
Logged In: YES 
user_id=80530


If the central cache is truly dangerous, then
it's very simple to remove [info library] and
make use of per-user caches only.

Sadly, yes, all the per-* restictions are needed.
The only way to get around that is to cache
the index script themselves rather than the
results of running them.  Too much depends
on interpreter state to do otherwise.


----------------------------------------------------------------------

Comment By: Don Porter (dgp)
Date: 2003-03-04 12:27

Message:
Logged In: YES 
user_id=80530

just to clarify one point: I do not
propose that this patch be
integrated into the official Tcl
sources.  Instead, it should
remain here as an aftermarket
add-on that sysadmins can
add (and tweak) *if* they find
that startup times on their systems
are a serious problem.

Alternative approaches are welcome
and could also be offered on the
same terms.


----------------------------------------------------------------------

Comment By: Joe English (jenglish)
Date: 2003-03-04 12:20

Message:
Logged In: YES 
user_id=68433

This approach looks overly complicated and error-prone to
me.

It's especially dangerous to automatically generate the
central package index in [info library] in the [package
unknown] handler -- this is something that should be left up
to the system administrator to do by hand.

It it necessary to parameterize the cache by [info
hostname], [info nameofexecutable], and the value of
$::auto_path? Why would the same program need a different
cache on different hosts?  (Actually, I think it would be
best if any Tcl program with the same [info library] could
use the same package cache, but there are pkgIndex.tcl
scripts which use (IMO overly-)clever heuristics to decide
whether or not to register 'ifneeded' scripts, so checking
[info nameofexecutable] might be appropriate).

Instead of parameterizing the cache by the $::auto_path
value, it might make more sense to keep per-directory
caches; [package unknown] could check for a cache before
scanning for pkgIndex.tcl files while processing
$::auto_path.


----------------------------------------------------------------------

Comment By: Don Porter (dgp)
Date: 2003-03-04 09:30

Message:
Logged In: YES 
user_id=80530

corrected patch

----------------------------------------------------------------------

Comment By: Don Porter (dgp)
Date: 2003-03-04 09:27

Message:
Logged In: YES 
user_id=80530

here is a first pass at a patch that
implements a cache for package indexes.

It's main method of maintaining
agreement with what is installed
is via a cache miss.  A miss triggers
a rebuild of the cache.  So, at any
time you can rebuild the caches by

    package require non-existent-package

Until the scheme become more sohpisticated,
users of it should do that each time a package
is installed/uninstalled.  Revisions to improve on
this are welcome.



----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=360894&aid=680169&group_id=10894