[PATCH 3/6] Ref-count the filespecs used by diffcore
- From
Linus Torvalds <torvalds@linux-foundation.org>
- Date
- Oct 25, 2007, 18:19 UTC
- Message-ID
- <alpine.LFD.0.999.0710251117590.30120@woody.linux-foundation.org>
- In-Reply-To
- <alpine.LFD.0.999.0710251112120.30120@woody.linux-foundation.org>
From: Linus Torvalds <torvalds@linux-foundation.org> 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@linux-foundation.org> ---
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