path: root/diffcore.h
diff options
authorLinus Torvalds <>2007-10-25 18:20:56 (GMT)
committerJunio C Hamano <>2007-10-27 06:18:06 (GMT)
commit644797119d7a3b7a043a51a9cccd8758f8451f91 (patch)
treeed4e6fb50c33a3fe92028747244f7106b0a3a2fe /diffcore.h
parent9fb88419ba85e641006c80db53620423f37f1c93 (diff)
copy vs rename detection: avoid unnecessary O(n*m) loops
The core rename detection had some rather stupid code to check if a pathname was used by a later modification or rename, which basically walked the whole pathname space for all renames for each rename, in order to tell whether it was a pure rename (no remaining users) or should be considered a copy (other users of the source file remaining). That's really silly, since we can just keep a count of users around, and replace all those complex and expensive loops with just testing that simple counter (but this all depends on the previous commit that shared the diff_filespec data structure by using a separate reference count). Note that the reference count is not the same as the rename count: they behave otherwise rather similarly, but the reference count is tied to the allocation (and decremented at de-allocation, so that when it turns zero we can get rid of the memory), while the rename count is tied to the renames and is decremented when we find a rename (so that when it turns zero we know that it was a rename, not a copy). Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'diffcore.h')
1 files changed, 1 insertions, 1 deletions
diff --git a/diffcore.h b/diffcore.h
index 30055ac..cc96c20 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -31,6 +31,7 @@ struct diff_filespec {
unsigned long size;
int count; /* Reference count */
int xfrm_flags; /* for use by the xfrm */
+ int rename_used; /* Count of rename users */
unsigned short mode; /* file mode */
unsigned sha1_valid : 1; /* if true, use sha1 and trust mode;
* if false, use the name and read from
@@ -58,7 +59,6 @@ struct diff_filepair {
struct diff_filespec *two;
unsigned short int score;
char status; /* M C R N D U (see Documentation/diff-format.txt) */
- unsigned source_stays : 1; /* all of R/C are copies */
unsigned broken_pair : 1;
unsigned renamed_pair : 1;
unsigned is_unmerged : 1;