11d45a6e6a
Now that all of the groundwork has been laid to support reading and
using pseudo-merges, make use of that work in this commit by teaching
the pack-bitmap machinery to use pseudo-merge(s) when available during
traversal.
The basic operation is as follows:
- When enumerating objects on either side of a reachability query,
first see if any subset of the roots satisfies some pseudo-merge
bitmap. If it does, apply that pseudo-merge bitmap.
- If any pseudo-merge bitmap(s) were applied in the previous step, OR
them into the result[^1]. Then repeat the process over all
pseudo-merge bitmaps (we'll refer to this as "cascading"
pseudo-merges). Once this is done, OR in the resulting bitmap.
- If there is no fill-in traversal to be done, return the bitmap for
that side of the reachability query. If there is fill-in traversal,
then for each commit we encounter via show_commit(), check to see if
any unsatisfied pseudo-merges containing that commit as one of its
parents has been made satisfied by the presence of that commit.
If so, OR in the object set from that pseudo-merge bitmap, and then
cascade. If not, continue traversal.
A similar implementation is present in the boundary-based bitmap
traversal routines.
[^1]: Importantly, we cannot OR in the entire set of roots along with
the objects reachable from whatever pseudo-merge bitmaps were
satisfied. This may leave some dangling bits corresponding to any
unsatisfied root(s) getting OR'd into the resulting bitmap, tricking
other parts of the traversal into thinking we already have a
reachability closure over those commit(s) when we do not.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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