index: add trace2 region for clear skip worktree

When using sparse checkout, clear_skip_worktree_from_present_files() must
enumerate index entries to find ones with the SKIP_WORKTREE bit to
determine whether those index entries exist on disk (in which case their
SKIP_WORKTREE bit should be removed).

In a large repository, this may take considerable time depending on the
size of the index.

Add a trace2 region to surface this information, keeping a count of how
many paths have been checked. Separately, keep counts after a full index is
materialized.

Signed-off-by: Anh Le <anh@canva.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

diff --git a/sparse-index.c b/sparse-index.c
index e4a54ce19433dd0cdd553996762af642ace0d9b8..8713a15611d5c175a2c67913a32a297fd761ca4b 100644 (file)
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -493,24 +493,40 @@ void clear_skip_worktree_from_present_files(struct index_state *istate)
        int dir_found = 1;
 
        int i;
+       int path_count[2] = {0, 0};
+       int restarted = 0;
 
        if (!core_apply_sparse_checkout ||
            sparse_expect_files_outside_of_patterns)
                return;
 
+       trace2_region_enter("index", "clear_skip_worktree_from_present_files",
+                           istate->repo);
 restart:
        for (i = 0; i < istate->cache_nr; i++) {
                struct cache_entry *ce = istate->cache[i];
 
-               if (ce_skip_worktree(ce) &&
-                   path_found(ce->name, &last_dirname, &dir_len, &dir_found)) {
-                       if (S_ISSPARSEDIR(ce->ce_mode)) {
-                               ensure_full_index(istate);
-                               goto restart;
+               if (ce_skip_worktree(ce)) {
+                       path_count[restarted]++;
+                       if (path_found(ce->name, &last_dirname, &dir_len, &dir_found)) {
+                               if (S_ISSPARSEDIR(ce->ce_mode)) {
+                                       ensure_full_index(istate);
+                                       restarted = 1;
+                                       goto restart;
+                               }
+                               ce->ce_flags &= ~CE_SKIP_WORKTREE;
                        }
-                       ce->ce_flags &= ~CE_SKIP_WORKTREE;
                }
        }
+
+       if (path_count[0])
+               trace2_data_intmax("index", istate->repo,
+                                  "sparse_path_count", path_count[0]);
+       if (restarted)
+               trace2_data_intmax("index", istate->repo,
+                                  "sparse_path_count_full", path_count[1]);
+       trace2_region_leave("index", "clear_skip_worktree_from_present_files",
+                           istate->repo);
 }
 
 /*