[PATCH v3] index: add trace2 region for clear skip worktree

From: Anh Le <anh@canva.com>

In a large repository using sparse checkout, checking whether a file marked with skip worktree is present on disk and its skip worktree bit should be cleared can take a considerable amount of time. Add a trace2 region to surface this information, keeping a count of how many paths have been checked and separately keep counts for after a full index is materialised.

Signed-off-by: Anh Le <anh@canva.com>
---
    index: add trace2 region for clear skip worktree
    
    In large repository using sparse checkout, checking whether a file
    marked with skip worktree is present on disk and its skip worktree bit
    should be cleared can take a considerable amount of time. Add a trace2
    region to surface this information.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1368%2FHaizzz%2Fmaster-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1368/Haizzz/master-v3
Pull-Request: https://github.com/git/git/pull/1368

Range-diff vs v2:

 1:  effe6b5b912 ! 1:  d0d9f258b08 index: add trace2 region for clear skip worktree
     @@ Metadata
       ## Commit message ##
          index: add trace2 region for clear skip worktree
      
     -    In a large repository using sparse checkout, checking
     -    whether a file marked with skip worktree is present
     -    on disk and its skip worktree bit should be cleared
     -    can take a considerable amount of time. Add a trace2
     -    region to surface this information, keeping a count of how many paths
     -    have been checked and separately
     -    keep counts for after a full index is
     -    materialised.
     +    In a large repository using sparse checkout, checking whether a file marked
     +    with skip worktree is present on disk and its skip worktree bit should be
     +    cleared can take a considerable amount of time. Add a trace2 region to
     +    surface this information, keeping a count of how many paths have been
     +    checked and separately keep counts for after a full index is materialised.
      
          Signed-off-by: Anh Le <anh@canva.com>
      
     @@ sparse-index.c: void clear_skip_worktree_from_present_files(struct index_state *
       	int dir_found = 1;
       
       	int i;
     -+	int path_counts[2] = {0, 0};
     ++	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);
     ++	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];
     @@ sparse-index.c: void clear_skip_worktree_from_present_files(struct index_state *
      -				ensure_full_index(istate);
      -				goto restart;
      +		if (ce_skip_worktree(ce)) {
     -+			path_counts[restarted]++;
     ++			path_count[restarted]++;
      +			if (path_found(ce->name, &last_dirname, &dir_len, &dir_found)) {
      +				if (S_ISSPARSEDIR(ce->ce_mode)) {
     ++					if (restarted)
     ++						BUG("ensure-full-index did not fully flatten?");
      +					ensure_full_index(istate);
      +					restarted = 1;
      +					goto restart;
     @@ sparse-index.c: void clear_skip_worktree_from_present_files(struct index_state *
       		}
       	}
      +
     -+	if (path_counts[0] > 0) {
     -+		trace2_data_intmax("index", istate->repo, "clear_skip_worktree_from_present_files/path_count", path_counts[0]);
     -+	}
     -+	if (restarted) {
     -+		trace2_data_intmax("index", istate->repo, "clear_skip_worktree_from_present_files/full_index/path_count", path_counts[1]);
     -+	}
     -+	trace2_region_leave("index", "clear_skip_worktree_from_present_files", istate->repo);
     ++	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);
       }
       
       /*

 sparse-index.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)