[PATCH] Use enhanced diff_delta() in the similarity estimator.

[PATCH] Use enhanced diff_delta() in the similarity estimator.

[Junio C Hamano]

The diff_delta() interface has been extended to reject
generating too big a delta while we were working on the packed
GIT archive format.  Take advantage of that when generating
delta in the similarity estimator used in diffcore-rename.c

Signed-off-by: Junio C Hamano <junkio@cox.net>
---

 diffcore-rename.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

e4495245cf1ffc1c443df9177c95ce9d1b5052b0
diff --git a/diffcore-rename.c b/diffcore-rename.c
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -136,6 +136,7 @@ static int estimate_similarity(struct di
 	 */
 	void *delta;
 	unsigned long delta_size, base_size, src_copied, literal_added;
+	unsigned long delta_limit;
 	int score;
 
 	/* We deal only with regular files.  Symlink renames are handled
@@ -163,9 +164,13 @@ static int estimate_similarity(struct di
 	if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
 		return 0; /* error but caught downstream */
 
+	delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
 	delta = diff_delta(src->data, src->size,
 			   dst->data, dst->size,
-			   &delta_size, ~0UL);
+			   &delta_size, delta_limit);
+	if (!delta)
+		/* If delta_limit is exceeded, we have too much differences */
+		return 0;
 
 	/* A delta that has a lot of literal additions would have
 	 * big delta_size no matter what else it does.
------------