Merge branch 'dk/gc-idx-wo-pack' into maint

Having a leftover .idx file without corresponding .pack file in
the repository hurts performance; "git gc" learned to prune them.

We may want to do the same for .bitmap (and notice but not prune
.keep) without corresponding .pack, but that can be a separate
topic.

* dk/gc-idx-wo-pack:
  gc: remove garbage .idx files from pack dir
  t5304: test cleaning pack garbage
  prepare_packed_git(): refactor garbage reporting in pack directory

builtin/count-objects.c

@@ -15,9 +15,31 @@ static int verbose;
 static unsigned long loose, packed, packed_loose;
 static off_t loose_size;
 
-static void real_report_garbage(const char *desc, const char *path)
+static const char *bits_to_msg(unsigned seen_bits)
+{
+	switch (seen_bits) {
+	case 0:
+		return "no corresponding .idx or .pack";
+	case PACKDIR_FILE_GARBAGE:
+		return "garbage found";
+	case PACKDIR_FILE_PACK:
+		return "no corresponding .idx";
+	case PACKDIR_FILE_IDX:
+		return "no corresponding .pack";
+	case PACKDIR_FILE_PACK|PACKDIR_FILE_IDX:
+	default:
+		return NULL;
+	}
+}
+
+static void real_report_garbage(unsigned seen_bits, const char *path)
 {
 	struct stat st;
+	const char *desc = bits_to_msg(seen_bits);
+
+	if (!desc)
+		return;
+
 	if (!stat(path, &st))
 		size_garbage += st.st_size;
 	warning("%s: %s", desc, path);
@@ -27,7 +49,7 @@ static void real_report_garbage(const char *desc, const char *path)
 static void loose_garbage(const char *path)
 {
 	if (verbose)
-		report_garbage("garbage found", path);
+		report_garbage(PACKDIR_FILE_GARBAGE, path);
 }
 
 static int count_loose(const unsigned char *sha1, const char *path, void *data)

builtin/gc.c

@@ -46,6 +46,22 @@ static struct argv_array rerere = ARGV_ARRAY_INIT;
 static struct tempfile pidfile;
 static struct lock_file log_lock;
 
+static struct string_list pack_garbage = STRING_LIST_INIT_DUP;
+
+static void clean_pack_garbage(void)
+{
+	int i;
+	for (i = 0; i < pack_garbage.nr; i++)
+		unlink_or_warn(pack_garbage.items[i].string);
+	string_list_clear(&pack_garbage, 0);
+}
+
+static void report_pack_garbage(unsigned seen_bits, const char *path)
+{
+	if (seen_bits == PACKDIR_FILE_IDX)
+		string_list_append(&pack_garbage, path);
+}
+
 static void git_config_date_string(const char *key, const char **output)
 {
 	if (git_config_get_string_const(key, output))
@@ -416,6 +432,11 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
 		return error(FAILED_RUN, rerere.argv[0]);
 
+	report_garbage = report_pack_garbage;
+	reprepare_packed_git();
+	if (pack_garbage.nr > 0)
+		clean_pack_garbage();
+
 	if (auto_gc && too_many_loose_objects())
 		warning(_("There are too many unreachable loose objects; "
 			"run 'git prune' to remove them."));

cache.h

@@ -1258,8 +1258,11 @@ struct pack_entry {
 
 extern struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path);
 
-/* A hook for count-objects to report invalid files in pack directory */
-extern void (*report_garbage)(const char *desc, const char *path);
+/* A hook to report invalid files in pack directory */
+#define PACKDIR_FILE_PACK 1
+#define PACKDIR_FILE_IDX 2
+#define PACKDIR_FILE_GARBAGE 4
+extern void (*report_garbage)(unsigned seen_bits, const char *path);
 
 extern void prepare_packed_git(void);
 extern void reprepare_packed_git(void);

path.c

@@ -147,7 +147,7 @@ void report_linked_checkout_garbage(void)
 		strbuf_setlen(&sb, len);
 		strbuf_addstr(&sb, path);
 		if (file_exists(sb.buf))
-			report_garbage("unused in linked checkout", sb.buf);
+			report_garbage(PACKDIR_FILE_GARBAGE, sb.buf);
 	}
 	strbuf_release(&sb);
 }

sha1_file.c

@@ -1228,27 +1228,16 @@ void install_packed_git(struct packed_git *pack)
 	packed_git = pack;
 }
 
-void (*report_garbage)(const char *desc, const char *path);
+void (*report_garbage)(unsigned seen_bits, const char *path);
 
 static void report_helper(const struct string_list *list,
 			  int seen_bits, int first, int last)
 {
-	const char *msg;
-	switch (seen_bits) {
-	case 0:
-		msg = "no corresponding .idx or .pack";
-		break;
-	case 1:
-		msg = "no corresponding .idx";
-		break;
-	case 2:
-		msg = "no corresponding .pack";
-		break;
-	default:
+	if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
 		return;
-	}
+
 	for (; first < last; first++)
-		report_garbage(msg, list->items[first].string);
+		report_garbage(seen_bits, list->items[first].string);
 }
 
 static void report_pack_garbage(struct string_list *list)
@@ -1271,7 +1260,7 @@ static void report_pack_garbage(struct string_list *list)
 		if (baselen == -1) {
 			const char *dot = strrchr(path, '.');
 			if (!dot) {
-				report_garbage("garbage found", path);
+				report_garbage(PACKDIR_FILE_GARBAGE, path);
 				continue;
 			}
 			baselen = dot - path + 1;
@@ -1343,7 +1332,7 @@ static void prepare_packed_git_one(char *objdir, int local)
 		    ends_with(de->d_name, ".keep"))
 			string_list_append(&garbage, path.buf);
 		else
-			report_garbage("garbage found", path.buf);
+			report_garbage(PACKDIR_FILE_GARBAGE, path.buf);
 	}
 	closedir(dir);
 	report_pack_garbage(&garbage);

t/t5304-prune.sh

@@ -219,6 +219,7 @@ test_expect_success 'gc: prune old objects after local clone' '
 
 test_expect_success 'garbage report in count-objects -v' '
 	test_when_finished "rm -f .git/objects/pack/fake*" &&
+	test_when_finished "rm -f .git/objects/pack/foo*" &&
 	: >.git/objects/pack/foo &&
 	: >.git/objects/pack/foo.bar &&
 	: >.git/objects/pack/foo.keep &&
@@ -244,6 +245,26 @@ EOF
 	test_cmp expected actual
 '
 
+test_expect_success 'clean pack garbage with gc' '
+	test_when_finished "rm -f .git/objects/pack/fake*" &&
+	test_when_finished "rm -f .git/objects/pack/foo*" &&
+	: >.git/objects/pack/foo.keep &&
+	: >.git/objects/pack/foo.pack &&
+	: >.git/objects/pack/fake.idx &&
+	: >.git/objects/pack/fake2.keep &&
+	: >.git/objects/pack/fake2.idx &&
+	: >.git/objects/pack/fake3.keep &&
+	git gc &&
+	git count-objects -v 2>stderr &&
+	grep "^warning:" stderr | sort >actual &&
+	cat >expected <<\EOF &&
+warning: no corresponding .idx or .pack: .git/objects/pack/fake3.keep
+warning: no corresponding .idx: .git/objects/pack/foo.keep
+warning: no corresponding .idx: .git/objects/pack/foo.pack
+EOF
+	test_cmp expected actual
+'
+
 test_expect_success 'prune .git/shallow' '
 	SHA1=`echo hi|git commit-tree HEAD^{tree}` &&
 	echo $SHA1 >.git/shallow &&