diff mbox series

[v2,8/8] sparse-checkout: clear tracked sparse dirs

Message ID f74015a2be97eff51ade75a2af95a6e13309a8f2.1628625014.git.gitgitgadget@gmail.com (mailing list archive)
State Superseded
Headers show
Series Sparse index: delete ignored files outside sparse cone | expand

Commit Message

Derrick Stolee Aug. 10, 2021, 7:50 p.m. UTC
From: Derrick Stolee <dstolee@microsoft.com>

When changing the scope of a sparse-checkout using cone mode, we might
have some tracked directories go out of scope. The current logic removes
the tracked files from within those directories, but leaves the ignored
files within those directories. This is a bit unexpected to users who
have given input to Git saying they don't need those directories
anymore.

This is something that is new to the cone mode pattern type: the user
has explicitly said "I want these directories and _not_ those
directories." The typical sparse-checkout patterns more generally apply
to "I want files with with these patterns" so it is natural to leave
ignored files as they are. This focus on directories in cone mode
provides us an opportunity to change the behavior.

Leaving these ignored files in the sparse directories makes it
impossible to gain performance benefits in the sparse index. When we
track into these directories, we need to know if the files are ignored
or not, which might depend on the _tracked_ .gitignore file(s) within
the sparse directory. This depends on the indexed version of the file,
so the sparse directory must be expanded.

By deleting the sparse directories when changing scope (or running 'git
sparse-checkout reapply') we regain these performance benefits as if the
repository was in a clean state.

Since these ignored files are frequently build output or helper files
from IDEs, the users should not need the files now that the tracked
files are removed. If the tracked files reappear, then they will have
newer timestamps than the build artifacts, so the artifacts will need to
be regenerated anyway.

Use the sparse-index as a data structure in order to find the sparse
directories that can be safely deleted. Re-expand the index to a full
one if it was full before.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/git-sparse-checkout.txt |  8 +++
 builtin/sparse-checkout.c             | 95 +++++++++++++++++++++++++++
 t/t1091-sparse-checkout-builtin.sh    | 59 +++++++++++++++++
 3 files changed, 162 insertions(+)
diff mbox series

Patch

diff --git a/Documentation/git-sparse-checkout.txt b/Documentation/git-sparse-checkout.txt
index fdcf43f87cb..f9022b9d555 100644
--- a/Documentation/git-sparse-checkout.txt
+++ b/Documentation/git-sparse-checkout.txt
@@ -210,6 +210,14 @@  case-insensitive check. This corrects for case mismatched filenames in the
 'git sparse-checkout set' command to reflect the expected cone in the working
 directory.
 
+The cone mode sparse-checkout patterns will also remove ignored files that
+are not within the sparse-checkout definition. This is important behavior
+to preserve the performance of the sparse index, but also matches that
+cone mode patterns care about directories, not files. If there exist files
+that are untracked and not ignored, then Git will not delete files within
+that directory other than the tracked files that are now out of scope.
+These files should be removed manually to ensure Git can behave optimally.
+
 
 SUBMODULES
 ----------
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 8ba9f13787b..b06c8f885ac 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -100,6 +100,99 @@  static int sparse_checkout_list(int argc, const char **argv)
 	return 0;
 }
 
+static void clean_tracked_sparse_directories(struct repository *r)
+{
+	int i, was_full = 0;
+	struct strbuf path = STRBUF_INIT;
+	size_t pathlen;
+	struct string_list_item *item;
+	struct string_list sparse_dirs = STRING_LIST_INIT_DUP;
+
+	/*
+	 * If we are not using cone mode patterns, then we cannot
+	 * delete directories outside of the sparse cone.
+	 */
+	if (!r || !r->index || !r->worktree)
+		return;
+	init_sparse_checkout_patterns(r->index);
+	if (!r->index->sparse_checkout_patterns ||
+	    !r->index->sparse_checkout_patterns->use_cone_patterns)
+		return;
+
+	/*
+	 * Use the sparse index as a data structure to assist finding
+	 * directories that are safe to delete. This conversion to a
+	 * sparse index will not delete directories that contain
+	 * conflicted entries or submodules.
+	 */
+	if (!r->index->sparse_index) {
+		/*
+		 * If something, such as a merge conflict or other concern,
+		 * prevents us from converting to a sparse index, then do
+		 * not try deleting files.
+		 */
+		if (convert_to_sparse(r->index, SPARSE_INDEX_IGNORE_CONFIG))
+			return;
+		was_full = 1;
+	}
+
+	strbuf_addstr(&path, r->worktree);
+	strbuf_complete(&path, '/');
+	pathlen = path.len;
+
+	/*
+	 * Collect directories that have gone out of scope but also
+	 * exist on disk, so there is some work to be done. We need to
+	 * store the entries in a list before exploring, since that might
+	 * expand the sparse-index again.
+	 */
+	for (i = 0; i < r->index->cache_nr; i++) {
+		struct cache_entry *ce = r->index->cache[i];
+
+		if (S_ISSPARSEDIR(ce->ce_mode) &&
+		    repo_file_exists(r, ce->name))
+			string_list_append(&sparse_dirs, ce->name);
+	}
+
+	for_each_string_list_item(item, &sparse_dirs) {
+		struct dir_struct dir = DIR_INIT;
+		struct pathspec p = { 0 };
+		struct strvec s = STRVEC_INIT;
+
+		strbuf_setlen(&path, pathlen);
+		strbuf_addstr(&path, item->string);
+
+		dir.flags |= DIR_SHOW_IGNORED_TOO;
+
+		setup_standard_excludes(&dir);
+		strvec_push(&s, path.buf);
+
+		parse_pathspec(&p, PATHSPEC_GLOB, 0, NULL, s.v);
+		fill_directory(&dir, r->index, &p);
+
+		if (dir.nr) {
+			warning(_("directory '%s' contains untracked files,"
+				  " but is not in the sparse-checkout cone"),
+				item->string);
+		} else if (remove_dir_recursively(&path, 0)) {
+			/*
+			 * Removal is "best effort". If something blocks
+			 * the deletion, then continue with a warning.
+			 */
+			warning(_("failed to remove directory '%s'"),
+				item->string);
+		}
+
+		dir_clear(&dir);
+	}
+
+	string_list_clear(&sparse_dirs, 0);
+	strbuf_release(&path);
+
+	if (was_full)
+		ensure_full_index(r->index);
+}
+
 static int update_working_directory(struct pattern_list *pl)
 {
 	enum update_sparsity_result result;
@@ -141,6 +234,8 @@  static int update_working_directory(struct pattern_list *pl)
 	else
 		rollback_lock_file(&lock_file);
 
+	clean_tracked_sparse_directories(r);
+
 	r->index->sparse_checkout_patterns = NULL;
 	return result;
 }
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index 38fc8340f5c..71236981e64 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -642,4 +642,63 @@  test_expect_success MINGW 'cone mode replaces backslashes with slashes' '
 	check_files repo/deep a deeper1
 '
 
+test_expect_success 'cone mode clears ignored subdirectories' '
+	rm repo/.git/info/sparse-checkout &&
+
+	git -C repo sparse-checkout init --cone &&
+	git -C repo sparse-checkout set deep/deeper1 &&
+
+	cat >repo/.gitignore <<-\EOF &&
+	obj/
+	*.o
+	EOF
+
+	git -C repo add .gitignore &&
+	git -C repo commit -m ".gitignore" &&
+
+	mkdir -p repo/obj repo/folder1/obj repo/deep/deeper2/obj &&
+	for file in folder1/obj/a obj/a folder1/file.o folder1.o \
+		    deep/deeper2/obj/a deep/deeper2/file.o file.o
+	do
+		echo ignored >repo/$file || return 1
+	done &&
+
+	git -C repo status --porcelain=v2 >out &&
+	test_must_be_empty out &&
+
+	git -C repo sparse-checkout reapply &&
+	test_path_is_missing repo/folder1 &&
+	test_path_is_missing repo/deep/deeper2 &&
+	test_path_is_dir repo/obj &&
+	test_path_is_file repo/file.o &&
+
+	git -C repo status --porcelain=v2 >out &&
+	test_must_be_empty out &&
+
+	git -C repo sparse-checkout set deep/deeper2 &&
+	test_path_is_missing repo/deep/deeper1 &&
+	test_path_is_dir repo/deep/deeper2 &&
+	test_path_is_dir repo/obj &&
+	test_path_is_file repo/file.o &&
+
+	>repo/deep/deeper2/ignored.o &&
+	>repo/deep/deeper2/untracked &&
+
+	# When an untracked file is in the way, all untracked files
+	# (even ignored files) are preserved.
+	git -C repo sparse-checkout set folder1 2>err &&
+	grep "contains untracked files" err &&
+	test_path_is_file repo/deep/deeper2/ignored.o &&
+	test_path_is_file repo/deep/deeper2/untracked &&
+
+	# The rest of the cone matches expectation
+	test_path_is_missing repo/deep/deeper1 &&
+	test_path_is_dir repo/obj &&
+	test_path_is_file repo/file.o &&
+
+	git -C repo status --porcelain=v2 >out &&
+	echo "? deep/deeper2/untracked" >expect &&
+	test_cmp expect out
+'
+
 test_done