This is the first of several "small" patches that follow the serialized Git commit graph patch (ds/commit-graph).
As described in Documentation/technical/commit-graph.txt, the generation number of a commit is one more than the maximum generation number among its parents (trivially, a commit with no parents has generation number one). This series makes the computation of generation numbers part of the commit-graph write process. Finally, generation numbers are used to order commits in the priority queue in paint_down_to_common(). This allows a constant-time check in queue_has_nonstale() instead of the previous linear-time check. This does not have a significant performance benefit in repositories of normal size, but in the Windows repository, some merge-base calculations improve from 3.1s to 2.9s. A modest speedup, but provides an actual consumer of generation numbers as a starting point. A more substantial refactoring of revision.c is required before making 'git log --graph' use generation numbers effectively. This patch series depends on v7 of ds/commit-graph. Derrick Stolee (6): object.c: parse commit in graph first commit: add generation number to struct commmit commit-graph: compute generation numbers commit: sort by generation number in paint_down_to_common() commit.c: use generation number to stop merge-base walks commit-graph.txt: update design doc with generation numbers Documentation/technical/commit-graph.txt | 7 +--- alloc.c | 1 + commit-graph.c | 48 +++++++++++++++++++++ commit.c | 53 ++++++++++++++++++++---- commit.h | 7 +++- object.c | 4 +- 6 files changed, 104 insertions(+), 16 deletions(-) -- 2.17.0.20.g9f30ba16e1
