treewide: add reasons for expanding index

These locations that previously called ensure_full_index() are now
updated to call the ..._with_reason() varation using fixed strings that
should be enough to identify the reason for the expansion.

This will help users use tracing to determine why the index is expanding
in their scenarios.

Signed-off-by: Derrick Stolee <[email protected]>
Signed-off-by: Johannes Schindelin <[email protected]>

Author: derrickstolee

builtin/checkout-index.c

@@ -156,7 +156,8 @@ static int checkout_all(const char *prefix, int prefix_length)
 			 * first entry inside the expanded sparse directory).
 			 */
 			if (ignore_skip_worktree) {
-				ensure_full_index(the_repository->index);
+				ensure_full_index_with_reason(the_repository->index,
+							      "checkout-index");
 				ce = the_repository->index->cache[i];
 			}
 		}

builtin/ls-files.c

@@ -413,7 +413,7 @@ static void show_files(struct repository *repo, struct dir_struct *dir)
 		return;
 
 	if (!show_sparse_dirs)
-		ensure_full_index(repo->index);
+		ensure_full_index_with_reason(repo->index, "ls-files");
 
 	for (i = 0; i < repo->index->cache_nr; i++) {
 		const struct cache_entry *ce = repo->index->cache[i];

builtin/read-tree.c

@@ -226,7 +226,8 @@ int cmd_read_tree(int argc,
 		setup_work_tree();
 
 	if (opts.skip_sparse_checkout)
-		ensure_full_index(the_repository->index);
+		ensure_full_index_with_reason(the_repository->index,
+					      "read-tree");
 
 	if (opts.merge) {
 		switch (stage - 1) {

builtin/reset.c

@@ -262,7 +262,8 @@ static int read_from_tree(const struct pathspec *pathspec,
 	opt.add_remove = diff_addremove;
 
 	if (pathspec->nr && pathspec_needs_expanded_index(the_repository->index, pathspec))
-		ensure_full_index(the_repository->index);
+		ensure_full_index_with_reason(the_repository->index,
+					      "reset pathspec");
 
 	if (do_diff_cache(tree_oid, &opt))
 		return 1;

builtin/rm.c

@@ -313,7 +313,8 @@ int cmd_rm(int argc,
 	seen = xcalloc(pathspec.nr, 1);
 
 	if (pathspec_needs_expanded_index(the_repository->index, &pathspec))
-		ensure_full_index(the_repository->index);
+		ensure_full_index_with_reason(the_repository->index,
+					      "rm pathspec");
 
 	for (i = 0; i < the_repository->index->cache_nr; i++) {
 		const struct cache_entry *ce = the_repository->index->cache[i];

builtin/sparse-checkout.c

@@ -207,7 +207,8 @@ static void clean_tracked_sparse_directories(struct repository *r)
 	strbuf_release(&path);
 
 	if (was_full)
-		ensure_full_index(r->index);
+		ensure_full_index_with_reason(r->index,
+				"sparse-checkout:was full");
 }
 
 static int update_working_directory(struct pattern_list *pl)
@@ -437,7 +438,8 @@ static int update_modes(int *cone_mode, int *sparse_index)
 		the_repository->index->updated_workdir = 1;
 
 		if (!*sparse_index)
-			ensure_full_index(the_repository->index);
+			ensure_full_index_with_reason(the_repository->index,
+				"sparse-checkout:disabling sparse index");
 	}
 
 	return 0;

read-cache.c

@@ -2376,7 +2376,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 	 */
 	prepare_repo_settings(istate->repo);
 	if (istate->repo->settings.command_requires_full_index)
-		ensure_full_index(istate);
+		ensure_full_index_with_reason(istate, "incompatible builtin");
 	else
 		ensure_correct_sparsity(istate);
 
@@ -3208,7 +3208,7 @@ static int do_write_locked_index(struct index_state *istate,
 				   "%s", get_lock_file_path(lock));
 
 	if (was_full)
-		ensure_full_index(istate);
+		ensure_full_index_with_reason(istate, "re-expanding after write");
 
 	if (ret)
 		return ret;
@@ -3319,7 +3319,7 @@ static int write_shared_index(struct index_state *istate,
 				   the_repository, "%s", get_tempfile_path(*temp));
 
 	if (was_full)
-		ensure_full_index(istate);
+		ensure_full_index_with_reason(istate, "re-expanding after write");
 
 	if (ret)
 		return ret;

repository.c

@@ -434,7 +434,7 @@ int repo_read_index(struct repository *repo)
 
 	prepare_repo_settings(repo);
 	if (repo->settings.command_requires_full_index)
-		ensure_full_index(repo->index);
+		ensure_full_index_with_reason(repo->index, "incompatible builtin");
 
 	/*
 	 * If sparse checkouts are in use, check whether paths with the

sequencer.c

@@ -797,7 +797,7 @@ static int do_recursive_merge(struct repository *r,
 		merge_switch_to_result(&o, head_tree, &result, 1, show_output);
 		clean = result.clean;
 	} else {
-		ensure_full_index(r->index);
+		ensure_full_index_with_reason(r->index, "non-ort merge strategy");
 		clean = merge_trees(&o, head_tree, next_tree, base_tree);
 		if (is_rebase_i(opts) && clean <= 0)
 			fputs(o.obuf.buf, stdout);
@@ -2574,7 +2574,7 @@ static int read_and_refresh_cache(struct repository *r,
 	 * expand the sparse index.
 	 */
 	if (opts->strategy && strcmp(opts->strategy, "ort"))
-		ensure_full_index(r->index);
+		ensure_full_index_with_reason(r->index, "non-ort merge strategy");
 	return 0;
 }
 

sparse-index.c

@@ -490,7 +490,8 @@ void ensure_correct_sparsity(struct index_state *istate)
 	if (is_sparse_index_allowed(istate, 0))
 		convert_to_sparse(istate, 0);
 	else
-		ensure_full_index(istate);
+		ensure_full_index_with_reason(istate,
+					      "sparse index not allowed");
 }
 
 struct path_found_data {
@@ -693,7 +694,8 @@ void clear_skip_worktree_from_present_files(struct index_state *istate)
 		return;
 
 	if (clear_skip_worktree_from_present_files_sparse(istate)) {
-		ensure_full_index(istate);
+		ensure_full_index_with_reason(istate,
+			"failed to clear skip-worktree while sparse");
 		clear_skip_worktree_from_present_files_full(istate);
 	}
 }

t/t1092-sparse-checkout-compatibility.sh

@@ -2500,4 +2500,12 @@ test_expect_success 'cat-file --batch' '
 	ensure_expanded cat-file --batch <in
 '
 
+test_expect_success 'ensure_full_index_with_reason' '
+	init_repos &&
+
+	GIT_TRACE2_EVENT="$(pwd)/ls-files-trace" \
+		git -C sparse-index ls-files --no-sparse HEAD &&
+	test_trace2_data "sparse-index" "expansion-reason" "ls-files" <ls-files-trace
+'
+
 test_done

unpack-trees.c

@@ -1936,9 +1936,9 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 
 	prepare_repo_settings(repo);
 	if (repo->settings.command_requires_full_index) {
-		ensure_full_index(o->src_index);
+		ensure_full_index_with_reason(o->src_index, "incompatible builtin");
 		if (o->dst_index)
-			ensure_full_index(o->dst_index);
+			ensure_full_index_with_reason(o->dst_index, "incompatible builtin");
 	}
 
 	if (o->reset == UNPACK_RESET_OVERWRITE_UNTRACKED &&