In the scheduler we always have to loop back to the beginning after
we don't find the last entry, so let's implement this in a new lookup
function instead. The resulting code is slightly faster, mostly due
to the fact that there's much less inlined code in the fast path.
Now when looking up a node via eb32sc_first(), eb32sc_next(), and
eb32sc_lookup_ge(), we only focus on the branches matching the requested
scope. The code must be careful to miss no branch. It changes a little
bit from the previous one because the scope stored on the intermediary
nodes is not exact (since we don't propagate upwards during deletion),
so in case a lookup fails, we have to walk up and pick the next matching
entry.
A new kind of tree nodes is currently being developed in ebtree v7,
consisting in storing a scope in each node indicating a visibility
mask so that certain nodes are not reported on certain lookups. The
initial goal was to make this usable with a multi-thread scheduler.
Since the ebtree v7 code is completely different from v6, this patch
instead copies the minimally required functions from eb32 and ebtree
and calls them "eb32sc_*". At the moment the scope is not implemented,
it's only passed in arguments.
Willy Tarreau