Hi all,
as those that tried know, we currently have a number of issues with the
locking.

On problem is that shlock style locking requires to create a file, e.g.
it requires to have the WRKDIR present. This is problematic when using
clean as part of the build targets.

To avoid this, I propose to add a simple tool (~40 lines at most) that
uses flock(2) to lock either the Makefile or the package location.
This has the huge advantage of not requiring the wrkdir to persist and
the kernel automatically keeps track of them.

There are two issues with this approach:
(1) This tool is currently not part of any BSD, so it adds a dependency.
(2) Null mounts currently don't create separate enough vnodes, so you
can't use e.g. two pkg_comp jails and build from the same pkgsrc tree.

I don't think either is an issue. Install it, if you want it. How much
sense does the locking make if you use chroots anyway?

Joerg