http://arch.newtral.org/{archives}/arch-2003

Again, if it is accepted, I'll add the necessary documentation.

Add final corrections:
linuxnow@newtral.org--arch-2003/tla--devo--1.1--patch-9
linuxnow@newtral.org--arch-2003/tla--devo--1.1--patch-10

The final hook name is `find-cached-revision'. An example of hook script follows:

...
case $1 in
...
find-cached-revision)
        # echo "find-cached-revision $ARCH_ARCHIVE/$ARCH_REVISION" | mail pau -s "find-cached-revision $ARCH_ARCHIVE/$ARCH_REVISION"
        # tla library-add $ARCH_ARCHIVE/$ARCH_REVISION
        tla library-add -d ~/.arch-cache $ARCH_ARCHIVE/$ARCH_REVISION
        echo -n "~/.arch-cache" 1>&3
        break
        ;;

esac

You can add a library in the hook, in the default revision library or in an alterante one and return the path to it using file descriptor 3.

If you always add a revision to the library, a pristine-tree is never generated because entries in libraries are searched for before. You save space because you share hard links and... if you get -l your tree, operation is almost instantaneous because you don't copy anything. Lightening fast.

It's working flawlessly for me.

As discussed, as a first step to farewell the inefficient pristine trees, we needed multi-path revision libraries and a way to create them on demand in an ad-hoc directory.

With sparse revision libraries and the possibility of specifying a path for the library commands, the only part missing was how to create and retrieve the revision form the desired tree. My choice has been to:
-add a way to exchange information with the hook script via fd 3; the hook script can return whatever it need via this fd and the hooks can use as they need or just ignore it.
-create a `cached-revision' hook that uses this information to look in the returned path for the revision, instead of the default library.

This is implemented in:
linuxnow@newtral.org--arch-2003/tla--devo--1.1--patch-7
linuxnow@newtral.org--arch-2003/tla--devo--1.1--patch-8

A complete description will be posted to the arch-users list.