Ref-count the filespecs used by diffcore

Rather than copy the filespecs when introducing new versions of them
(for rename or copy detection), use a refcount and increment the count
when reusing the diff_filespec.

This avoids unnecessary allocations, but the real reason behind this is
a future enhancement: we will want to track shared data across the
copy/rename detection.  In order to efficiently notice when a filespec
is used by a rename, the rename machinery wants to keep track of a
rename usage count which is shared across all different users of the
filespec.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 10 deletions

diff --git a/diffcore-rename.c b/diffcore-rename.c
index 2077a9b..3da06b7 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -209,21 +209,19 @@ static int estimate_similarity(struct diff_filespec *src,
 
 static void record_rename_pair(int dst_index, int src_index, int score)
 {
-	struct diff_filespec *one, *two, *src, *dst;
+	struct diff_filespec *src, *dst;
 	struct diff_filepair *dp;
 
 	if (rename_dst[dst_index].pair)
 		die("internal error: dst already matched.");
 
 	src = rename_src[src_index].one;
-	one = alloc_filespec(src->path);
-	fill_filespec(one, src->sha1, src->mode);
+	src->count++;
 
 	dst = rename_dst[dst_index].two;
-	two = alloc_filespec(dst->path);
-	fill_filespec(two, dst->sha1, dst->mode);
+	dst->count++;
 
-	dp = diff_queue(NULL, one, two);
+	dp = diff_queue(NULL, src, dst);
 	dp->renamed_pair = 1;
 	if (!strcmp(src->path, dst->path))
 		dp->score = rename_src[src_index].score;
@@ -526,10 +524,8 @@ void diffcore_rename(struct diff_options *options)
 		}
 	}
 
-	for (i = 0; i < rename_dst_nr; i++) {
-		diff_free_filespec_data(rename_dst[i].two);
-		free(rename_dst[i].two);
-	}
+	for (i = 0; i < rename_dst_nr; i++)
+		free_filespec(rename_dst[i].two);
 
 	free(rename_dst);
 	rename_dst = NULL;