We define a cyclic dependency as the possibility (!) of the prerequisites
of a package X including a package that depends on X, and issue an error
if encountering such a situation.
Note that, if the dependencies of X can be resolved in a manner that does
not include the cyclic dependency, qpkg will still fail if it encounters
the cycle. Also note that qpkg (at least so far) does no perform an
exhaustive search to ferret out cyclic dependencies.
Furthermore, we don't consider that a cyclic dependency may not necessarily
imply a real life problem. E.g., if a package A contains elements X and
Y, with X needing package B, and the content of package B has a run-time
dependency on Y, the cyclic dependency between A and B would not exist
when considering its constituents. Since we don't have this information, we
just err on the side of caution.
- qpkg.h (enum flags): divide flags into categories (parse-time and
run-time) and add flag QPKG_ADDING to mark packets whose dependencies we
are processing
- prereq.c (resolve, prereq): track which packages we're tentatively
considering for installation and detect cyclic dependencies
- test/cyclic: regression test for detection of cyclic dependencies
- TODO: updated with recent changes
- TODO: added section for tasks done
- TODO: search tree optimization is done
- TODO: added idea of supporting other database formats in the same family
- jrb.h, jrb.c (jrb_find_or_insert): new function to look for a node and
to insert a new one if not found
- id.c (make_id): use jrb_find_or_insert to avoid looking up new nodes
twice
- TODO: report the improvement
This is a change of the underlying mechanism but it's not polished or
optimized yet. The compare functions haven't been updated, so they work
but produce compiler warnings because of type mismatches.
- Makefile (OBJS): added jrb.o
- id.h, id.c: use jrb instead of own dumb binary trees
- TODO: brag about the efficiency improvement
