Merge branch 'vd/sparse-stash'

Teach "git stash" to work better with sparse index entries.

* vd/sparse-stash:
  unpack-trees: preserve index sparsity
  stash: apply stash using 'merge_ort_nonrecursive()'
  read-cache: set sparsity when index is new
  sparse-index: expose 'is_sparse_index_allowed()'
  stash: integrate with sparse index
  stash: expand sparse-checkout compatibility testing

builtin/stash.c

@@ -7,6 +7,7 @@
 #include "cache-tree.h"
 #include "unpack-trees.h"
 #include "merge-recursive.h"
+#include "merge-ort-wrappers.h"
 #include "strvec.h"
 #include "run-command.h"
 #include "dir.h"
@@ -492,13 +493,13 @@ static void unstage_changes_unless_new(struct object_id *orig_tree)
 static int do_apply_stash(const char *prefix, struct stash_info *info,
 			  int index, int quiet)
 {
-	int ret;
+	int clean, ret;
 	int has_index = index;
 	struct merge_options o;
 	struct object_id c_tree;
 	struct object_id index_tree;
-	struct commit *result;
-	const struct object_id *bases[1];
+	struct tree *head, *merge, *merge_base;
+	struct lock_file lock = LOCK_INIT;
 
 	read_cache_preload(NULL);
 	if (refresh_and_write_cache(REFRESH_QUIET, 0, 0))
@@ -541,6 +542,7 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 	o.branch1 = "Updated upstream";
 	o.branch2 = "Stashed changes";
+	o.ancestor = "Stash base";
 
 	if (oideq(&info->b_tree, &c_tree))
 		o.branch1 = "Version stash was based on";
@@ -551,10 +553,26 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 	if (o.verbosity >= 3)
 		printf_ln(_("Merging %s with %s"), o.branch1, o.branch2);
 
-	bases[0] = &info->b_tree;
+	head = lookup_tree(o.repo, &c_tree);
+	merge = lookup_tree(o.repo, &info->w_tree);
+	merge_base = lookup_tree(o.repo, &info->b_tree);
+
+	repo_hold_locked_index(o.repo, &lock, LOCK_DIE_ON_ERROR);
+	clean = merge_ort_nonrecursive(&o, head, merge, merge_base);
+
+	/*
+	 * If 'clean' >= 0, reverse the value for 'ret' so 'ret' is 0 when the
+	 * merge was clean, and nonzero if the merge was unclean or encountered
+	 * an error.
+	 */
+	ret = clean >= 0 ? !clean : clean;
+
+	if (ret < 0)
+		rollback_lock_file(&lock);
+	else if (write_locked_index(o.repo->index, &lock,
+				      COMMIT_LOCK | SKIP_IF_UNCHANGED))
+		ret = error(_("could not write index"));
 
-	ret = merge_recursive_generic(&o, &c_tree, &info->w_tree, 1, bases,
-				      &result);
 	if (ret) {
 		rerere(0);
 
@@ -1770,6 +1788,9 @@ int cmd_stash(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options, git_stash_usage,
 			     PARSE_OPT_KEEP_UNKNOWN | PARSE_OPT_KEEP_DASHDASH);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	index_file = get_index_file();
 	strbuf_addf(&stash_index_path, "%s.stash.%" PRIuMAX, index_file,
 		    (uintmax_t)pid);

read-cache.c

@@ -2260,6 +2260,20 @@ static unsigned long load_cache_entries_threaded(struct index_state *istate, con
 	return consumed;
 }
 
+static void set_new_index_sparsity(struct index_state *istate)
+{
+	/*
+	 * If the index's repo exists, mark it sparse according to
+	 * repo settings.
+	 */
+	if (istate->repo) {
+		prepare_repo_settings(istate->repo);
+		if (!istate->repo->settings.command_requires_full_index &&
+		    is_sparse_index_allowed(istate, 0))
+			istate->sparse_index = 1;
+	}
+}
+
 /* remember to discard_cache() before reading a different cache! */
 int do_read_index(struct index_state *istate, const char *path, int must_exist)
 {
@@ -2281,8 +2295,10 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 	istate->timestamp.nsec = 0;
 	fd = open(path, O_RDONLY);
 	if (fd < 0) {
-		if (!must_exist && errno == ENOENT)
+		if (!must_exist && errno == ENOENT) {
+			set_new_index_sparsity(istate);
 			return 0;
+		}
 		die_errno(_("%s: index file open failed"), path);
 	}
 

sparse-index.c

@@ -118,7 +118,7 @@ static int index_has_unmerged_entries(struct index_state *istate)
 	return 0;
 }
 
-static int is_sparse_index_allowed(struct index_state *istate, int flags)
+int is_sparse_index_allowed(struct index_state *istate, int flags)
 {
 	if (!core_apply_sparse_checkout || !core_sparse_checkout_cone)
 		return 0;

sparse-index.h

@@ -3,6 +3,7 @@
 
 struct index_state;
 #define SPARSE_INDEX_MEMORY_ONLY (1 << 0)
+int is_sparse_index_allowed(struct index_state *istate, int flags);
 int convert_to_sparse(struct index_state *istate, int flags);
 void ensure_correct_sparsity(struct index_state *istate);
 void clear_skip_worktree_from_present_files(struct index_state *istate);

t/perf/p2000-sparse-operations.sh

@@ -106,6 +106,8 @@ test_perf_on_all () {
 }
 
 test_perf_on_all git status
+test_perf_on_all 'git stash && git stash pop'
+test_perf_on_all 'echo >>new && git stash -u && git stash pop'
 test_perf_on_all git add -A
 test_perf_on_all git add .
 test_perf_on_all git commit -a -m A

t/t1092-sparse-checkout-compatibility.sh

@@ -1034,6 +1034,55 @@ test_expect_success 'cherry-pick with conflicts' '
 	test_all_match test_must_fail git cherry-pick to-cherry-pick
 '
 
+test_expect_success 'stash' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	# Stash a sparse directory (folder1)
+	test_all_match git checkout -b test-branch rename-base &&
+	test_all_match git reset --soft rename-out-to-out &&
+	test_all_match git stash &&
+	test_all_match git status --porcelain=v2 &&
+
+	# Apply the sparse directory stash without reinstating the index
+	test_all_match git stash apply -q &&
+	test_all_match git status --porcelain=v2 &&
+
+	# Reset to state where stash can be applied
+	test_sparse_match git sparse-checkout reapply &&
+	test_all_match git reset --hard rename-out-to-out &&
+
+	# Apply the sparse directory stash *with* reinstating the index
+	test_all_match git stash apply --index -q &&
+	test_all_match git status --porcelain=v2 &&
+
+	# Reset to state where we will get a conflict applying the stash
+	test_sparse_match git sparse-checkout reapply &&
+	test_all_match git reset --hard update-folder1 &&
+
+	# Apply the sparse directory stash with conflicts
+	test_all_match test_must_fail git stash apply --index -q &&
+	test_all_match test_must_fail git stash apply -q &&
+	test_all_match git status --porcelain=v2 &&
+
+	# Reset to base branch
+	test_sparse_match git sparse-checkout reapply &&
+	test_all_match git reset --hard base &&
+
+	# Stash & unstash an untracked file outside of the sparse checkout
+	# definition.
+	run_on_sparse mkdir -p folder1 &&
+	run_on_all ../edit-contents folder1/new &&
+	test_all_match git stash -u &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git stash pop -q &&
+	test_all_match git status --porcelain=v2
+'
+
 test_expect_success 'checkout-index inside sparse definition' '
 	init_repos &&
 
@@ -1222,7 +1271,10 @@ test_expect_success 'index.sparse disabled inline uses full index' '
 
 ensure_not_expanded () {
 	rm -f trace2.txt &&
-	echo >>sparse-index/untracked.txt &&
+	if test -z "$WITHOUT_UNTRACKED_TXT"
+	then
+		echo >>sparse-index/untracked.txt
+	fi &&
 
 	if test "$1" = "!"
 	then
@@ -1326,6 +1378,30 @@ test_expect_success 'sparse-index is not expanded: merge conflict in cone' '
 	)
 '
 
+test_expect_success 'sparse-index is not expanded: stash' '
+	init_repos &&
+
+	echo >>sparse-index/a &&
+	ensure_not_expanded stash &&
+	ensure_not_expanded stash list &&
+	ensure_not_expanded stash show stash@{0} &&
+	ensure_not_expanded stash apply stash@{0} &&
+	ensure_not_expanded stash drop stash@{0} &&
+
+	echo >>sparse-index/deep/new &&
+	ensure_not_expanded stash -u &&
+	(
+		WITHOUT_UNTRACKED_TXT=1 &&
+		ensure_not_expanded stash pop
+	) &&
+
+	ensure_not_expanded stash create &&
+	oid=$(git -C sparse-index stash create) &&
+	ensure_not_expanded stash store -m "test" $oid &&
+	ensure_not_expanded reset --hard &&
+	ensure_not_expanded stash pop
+'
+
 test_expect_success 'sparse index is not expanded: diff' '
 	init_repos &&
 

unpack-trees.c

@@ -11,6 +11,7 @@
 #include "refs.h"
 #include "attr.h"
 #include "split-index.h"
+#include "sparse-index.h"
 #include "submodule.h"
 #include "submodule-config.h"
 #include "fsmonitor.h"
@@ -1839,6 +1840,11 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	o->result.fsmonitor_last_update =
 		xstrdup_or_null(o->src_index->fsmonitor_last_update);
 
+	if (!o->src_index->initialized &&
+	    !repo->settings.command_requires_full_index &&
+	    is_sparse_index_allowed(&o->result, 0))
+		o->result.sparse_index = 1;
+
 	/*
 	 * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
 	 */