Performance optimization for detection of modified submodules

In the worst case is_submodule_modified() got called three times for
each submodule. The information we got from scanning the whole
submodule tree the first time can be reused instead.

New parameters have been added to diff_change() and diff_addremove(),
the information is stored in a new member of struct diff_filespec. Its
value is then reused instead of calling is_submodule_modified() again.

When no explicit "-dirty" is needed in the output the call to
is_submodule_modified() is not necessary when the submodules HEAD
already disagrees with the ref of the superproject, as this alone
marks it as modified. To achieve that, get_stat_data() got an extra
argument.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/diff.c b/diff.c
index 750c066a5..8986873c0 100644
--- a/diff.c
+++ b/diff.c
@@ -2032,7 +2032,7 @@ static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
 	char *data = xmalloc(100), *dirty = "";
 
 	/* Are we looking at the work tree? */
-	if (!s->sha1_valid && is_submodule_modified(s->path))
+	if (!s->sha1_valid && s->dirty_submodule)
 		dirty = "-dirty";
 
 	len = snprintf(data, 100,
@@ -3719,7 +3719,7 @@ int diff_result_code(struct diff_options *opt, int status)
 void diff_addremove(struct diff_options *options,
 		    int addremove, unsigned mode,
 		    const unsigned char *sha1,
-		    const char *concatpath)
+		    const char *concatpath, unsigned dirty_submodule)
 {
 	struct diff_filespec *one, *two;
 
@@ -3751,8 +3751,10 @@ void diff_addremove(struct diff_options *options,
 
 	if (addremove != '+')
 		fill_filespec(one, sha1, mode);
-	if (addremove != '-')
+	if (addremove != '-') {
 		fill_filespec(two, sha1, mode);
+		two->dirty_submodule = dirty_submodule;
+	}
 
 	diff_queue(&diff_queued_diff, one, two);
 	if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
@@ -3763,7 +3765,8 @@ void diff_change(struct diff_options *options,
 		 unsigned old_mode, unsigned new_mode,
 		 const unsigned char *old_sha1,
 		 const unsigned char *new_sha1,
-		 const char *concatpath)
+		 const char *concatpath,
+		 unsigned old_dirty_submodule, unsigned new_dirty_submodule)
 {
 	struct diff_filespec *one, *two;
 
@@ -3776,6 +3779,8 @@ void diff_change(struct diff_options *options,
 		const unsigned char *tmp_c;
 		tmp = old_mode; old_mode = new_mode; new_mode = tmp;
 		tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
+		tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
+			new_dirty_submodule = tmp;
 	}
 
 	if (options->prefix &&
@@ -3786,6 +3791,8 @@ void diff_change(struct diff_options *options,
 	two = alloc_filespec(concatpath);
 	fill_filespec(one, old_sha1, old_mode);
 	fill_filespec(two, new_sha1, new_mode);
+	one->dirty_submodule = old_dirty_submodule;
+	two->dirty_submodule = new_dirty_submodule;
 
 	diff_queue(&diff_queued_diff, one, two);
 	if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))