[0/6] Sparse Index: Integrate with merge, cherry-pick, rebase, and revert

Message

Philippe Blain via GitGitGadget Aug. 17, 2021, 5:08 p.m. UTC

This series integrates the sparse index with commands that perform merges
such as 'git merge', 'git cherry-pick', 'git revert' (free with
cherry-pick), and 'git rebase'.

When the ORT merge strategy is enabled, this allows most merges to succeed
without expanding the sparse index, leading to significant performance
gains. I tested these changes against an internal monorepo with over 2
million paths at HEAD but with a sparse-checkout that only has ~60,000 files
within the sparse-checkout cone. 'git merge' commands went from 5-6 seconds
to 0.750-1.250s.

In the case of the recursive merge strategy, the sparse index is expanded
before the recursive algorithm proceeds. We expect that this is as good as
we can get with that strategy. When the strategy shifts to ORT as the
default, then this will not be a problem except for users who decide to
change the behavior.

Most of the hard work was done by previous series, such as
ds/sparse-index-ignored-files (which this series is based on).

Thanks, -Stolee

Derrick Stolee (6):
  t1092: use ORT merge strategy
  diff: ignore sparse paths in diffstat
  merge: make sparse-aware with ORT
  merge-ort: expand only for out-of-cone conflicts
  t1092: add cherry-pick, rebase tests
  sparse-index: integrate with cherry-pick and rebase

 builtin/merge.c                          |  3 +
 builtin/rebase.c                         |  6 ++
 builtin/revert.c                         |  3 +
 diff.c                                   |  8 ++
 merge-ort.c                              | 16 ++++
 merge-recursive.c                        |  3 +
 t/t1092-sparse-checkout-compatibility.sh | 97 +++++++++++++++++++++---
 7 files changed, 124 insertions(+), 12 deletions(-)


base-commit: febef675f051eb08896751bb5661b6deb5579ead
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1019%2Fderrickstolee%2Fsparse-index%2Fmerge-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1019/derrickstolee/sparse-index/merge-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1019