path: root/builtin
diff options
authorElijah Newren <>2020-06-11 06:59:33 (GMT)
committerJunio C Hamano <>2020-06-13 00:27:16 (GMT)
commit7233f17577c63c95da0b4a23eefc26125e4971d1 (patch)
treef3723f824db3635569153b63112797eec06b9834 /builtin
parentf7f5c6c0baf6b6219b38e69d8623b95cc3cdd3d3 (diff)
clean: optimize and document cases where we recurse into subdirectories
Commit 6b1db43109 ("clean: teach clean -d to preserve ignored paths", 2017-05-23) added the following code block (among others) to git-clean: if (remove_directories) dir.flags |= DIR_SHOW_IGNORED_TOO | DIR_KEEP_UNTRACKED_CONTENTS; The reason for these flags is well documented in the commit message, but isn't obvious just from looking at the code. Add some explanations to the code to make it clearer. Further, it appears git-2.26 did not correctly handle this combination of flags from git-clean. With both these flags and without DIR_SHOW_IGNORED_TOO_MODE_MATCHING set, git is supposed to recurse into all untracked AND ignored directories. git-2.26.0 clearly was not doing that. I don't know the full reasons for that or whether git < 2.27.0 had additional unknown bugs because of that misbehavior, because I don't feel it's worth digging into. As per the huge changes and craziness documented in commit 8d92fb2927 ("dir: replace exponential algorithm with a linear one", 2020-04-01), the old algorithm was a mess and was thrown out. What I can say is that git-2.27.0 correctly recurses into untracked AND ignored directories with that combination. However, in clean's case we don't need to recurse into ignored directories; that is just a waste of time. Thus, when git-2.27.0 started correctly handling those flags, we got a performance regression report. Rather than relying on other bugs in fill_directory()'s former logic to provide the behavior of skipping ignored directories, make use of the DIR_SHOW_IGNORED_TOO_MODE_MATCHING value specifically added in commit eec0f7f2b7 ("status: add option to show ignored files differently", 2017-10-30) for this purpose. Reported-by: Brian Malehorn <> Signed-off-by: Elijah Newren <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'builtin')
1 files changed, 31 insertions, 2 deletions
diff --git a/builtin/clean.c b/builtin/clean.c
index 1be437b..5a9c29a 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -955,8 +955,37 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
remove_directories = 1;
- if (remove_directories && !ignored_only)
+ if (remove_directories && !ignored_only) {
+ /*
+ * We need to know about ignored files too:
+ *
+ * If (ignored), then we will delete ignored files as well.
+ *
+ * If (!ignored), then even though we not are doing
+ * anything with ignored files, we need to know about them
+ * so that we can avoid deleting a directory of untracked
+ * files that also contains an ignored file within it.
+ *
+ * For the (!ignored) case, since we only need to avoid
+ * deleting ignored files, we can set
+ * recursing into a directory which is itself ignored.
+ */
+ dir.flags |= DIR_SHOW_IGNORED_TOO;
+ if (!ignored)
+ /*
+ * Let the fill_directory() machinery know that we aren't
+ * just recursing to collect the ignored files; we want all
+ * the untracked ones so that we can delete them. (Note:
+ * we could also set DIR_KEEP_UNTRACKED_CONTENTS when
+ * ignored_only is true, since DIR_KEEP_UNTRACKED_CONTENTS
+ * only has effect in combination with DIR_SHOW_IGNORED_TOO. It makes
+ * the code clearer to exclude it, though.
+ */
+ }
if (read_cache() < 0)
die(_("index file corrupt"));