From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Subject: [PATCH 3/6] Ref-count the filespecs used by diffcore
Rather than copy the refcounts 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@xxxxxxxxxxxxxxxxxxxx>
---
This was sent out in the original series as a fix on top of broken code.
Now it sets up the infrastructure so that the next patch won't be broken.
diff.c | 15 +++++++++++----
diffcore-rename.c | 16 ++++++----------
diffcore.h | 2 ++
3 files changed, 19 insertions(+), 14 deletions(-)
diff --git a/diff.c b/diff.c
index dfb8595..0b320f6 100644
--- a/diff.c
+++ b/diff.c
@@ -1440,9 +1440,18 @@ struct diff_filespec *alloc_filespec(const char *path)
memset(spec, 0, sizeof(*spec));
spec->path = (char *)(spec + 1);
memcpy(spec->path, path, namelen+1);
+ spec->count = 1;
return spec;
}
+void free_filespec(struct diff_filespec *spec)
+{
+ if (!--spec->count) {
+ diff_free_filespec_data(spec);
+ free(spec);
+ }
+}
+
void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
unsigned short mode)
{
@@ -2435,10 +2444,8 @@ struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
void diff_free_filepair(struct diff_filepair *p)
{
- diff_free_filespec_data(p->one);
- diff_free_filespec_data(p->two);
- free(p->one);
- free(p->two);
+ free_filespec(p->one);
+ free_filespec(p->two);
free(p);
}
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;
diff --git a/diffcore.h b/diffcore.h
index eb618b1..30055ac 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -29,6 +29,7 @@ struct diff_filespec {
void *cnt_data;
const char *funcname_pattern_ident;
unsigned long size;
+ int count; /* Reference count */
int xfrm_flags; /* for use by the xfrm */
unsigned short mode; /* file mode */
unsigned sha1_valid : 1; /* if true, use sha1 and trust mode;
@@ -43,6 +44,7 @@ struct diff_filespec {
};
extern struct diff_filespec *alloc_filespec(const char *);
+extern void free_filespec(struct diff_filespec *);
extern void fill_filespec(struct diff_filespec *, const unsigned char *,
unsigned short);
--
1.5.3.4.330.g1dec6
-
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