[PATCH 1/2] pack-refs: remove all empty directories under $GIT_DIR/refs

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Deleting refs does not remove parent directories if they are empty.
Empty directories add extra overhead to startup time of most of git
commands because they have to traverse $GIT_DIR/refs.

Some directories are kept by this patch even if they are empty (refs,
refs/heads and refs/tags). The first one is one of git repository
signature. The rest is created by init-db, one may expect them to always
be there.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 v2, no more refs code change.

 Part of the reason I do not want to update delete_ref() is because it
 won't remove empty directories in existing repositories.

 pack-refs.c |   53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 53 insertions(+), 0 deletions(-)

diff --git a/pack-refs.c b/pack-refs.c
index f09a054..bb3a9c4 100644
--- a/pack-refs.c
+++ b/pack-refs.c
@@ -91,6 +91,58 @@ static void try_remove_empty_parents(char *name)
 	}
 }
 
+static int prune_empty_dirs(const char *path)
+{
+	int nr_entries = 0, pathlen = strlen(path);
+	DIR *dir;
+	struct dirent *de;
+	char *subpath;
+
+	dir = opendir(git_path("%s", path));
+
+	if (!dir)
+		return 0;
+
+	subpath = xmalloc(pathlen + 257);
+	memcpy(subpath, path, pathlen);
+	if (pathlen && path[pathlen-1] != '/')
+		subpath[pathlen++] = '/';
+
+	while ((de = readdir(dir)) != NULL) {
+		struct stat st;
+		int namelen;
+
+		if (de->d_name[0] == '.') {
+			if (strcmp(de->d_name, "..") && strcmp(de->d_name, "."))
+				nr_entries++;
+			continue;
+		}
+		nr_entries++;
+		namelen = strlen(de->d_name);
+		if (namelen > 255)
+			continue;
+		if (has_extension(de->d_name, ".lock"))
+			continue;
+		memcpy(subpath + pathlen, de->d_name, namelen+1);
+		if (stat(git_path("%s", subpath), &st) < 0)
+			continue;
+		if (S_ISDIR(st.st_mode)) {
+			int removed = prune_empty_dirs(subpath);
+			if (removed)
+				nr_entries--;
+			continue;
+		}
+	}
+	free(subpath);
+	closedir(dir);
+	if (nr_entries == 0 &&
+	    strcmp(path, "refs") &&
+	    strcmp(path, "refs/heads") &&
+	    strcmp(path, "refs/tags"))
+		return rmdir(git_path("%s", path)) == 0;
+	return 0;
+}
+
 /* make sure nobody touched the ref, and unlink */
 static void prune_ref(struct ref_to_prune *r)
 {
@@ -109,6 +161,7 @@ static void prune_refs(struct ref_to_prune *r)
 		prune_ref(r);
 		r = r->next;
 	}
+	prune_empty_dirs("refs");
 }
 
 static struct lock_file packed;
-- 
1.7.8.36.g69ee2