[PATCH 0/5] sparse-index: improve clear_skip_worktree_from_present_files()

While doing some investigation in a private monorepo with sparse-checkout and a sparse index, I accidentally left a modified file outside of my sparse-checkout cone. This caused my Git commands to slow to a crawl, so I reran with GIT_TRACE2_PERF=1.

While I was able to identify clear_skip_worktree_from_present_files() as the culprit, it took longer than desired to figure out what was going on. This series intends to both fix the performance issue (as much as possible) and do some refactoring to make it easier to understand what is happening.

In the end, I was able to reduce the number of lstat() calls in my case from over 170,000 to about 6,500, improving the time from 2.5s to 71ms on a warm disk cache.   Thanks, Stolee

Derrick Stolee (5):
  sparse-index: refactor skip worktree retry logic
  sparse-index: refactor path_found()
  sparse-index: use strbuf in path_found()
  sparse-index: count lstat() calls
  sparse-index: improve lstat caching of sparse paths

 sparse-index.c | 220 +++++++++++++++++++++++++++++++++++++------------
 1 file changed, 167 insertions(+), 53 deletions(-)

base-commit: 66ac6e4bcd111be3fa9c2a6b3fafea718d00678d
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1754%2Fderrickstolee%2Fclear-skip-speed-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1754/derrickstolee/clear-skip-speed-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1754