[PATCH 0/3] some prune optimizations

Here are two optimizations for git-prune that we've been running at GitHub for ages. No particular reason to share them now; they just finally floated to the top of my todo pile. Do note that I rebased and polished them (and the third one is brand new), so the concepts are proven, but it's possible I introduced a new bug. ;)

  [1/3]: prune: lazily perform reachability traversal
  [2/3]: prune: use bitmaps for reachability traversal
  [3/3]: prune: check SEEN flag for reachability

 builtin/prune.c       | 44 +++++++++++++++++++++++++++++++------------
 reachable.c           | 42 +++++++++++++++++++++++++++++++++++++++++
 t/perf/p5304-prune.sh | 35 ++++++++++++++++++++++++++++++++++
 t/t5304-prune.sh      | 12 ++++++++++++
 4 files changed, 121 insertions(+), 12 deletions(-)
 create mode 100755 t/perf/p5304-prune.sh

-Peff