Re: fact-import: failed to apply delta

["Shawn O. Pearce" <spearce@spearce.org>]

Daniel Barkalow <barkalow@iabervon.org> wrote:
> On Tue, 10 Feb 2009, Shawn O. Pearce wrote:
> > 
> > We should dump the cached_objects table in sha1_file.c during
> > a checkpoint in fast-import.
> 
> No, that one's keyed by sha1, and doesn't get collisions; it's the 
> delta_base_cache that's the issue; it's keyed by struct packed_git * and 
> offset.

Uh, yea, I realize that after I sent the message.  Does this patch
fix it for you?

--8<--
Clear the delta base cache during fast-import checkpoint

Otherwise we may reuse the same memory address for a totally
different "struct packed_git", and a previously cached object from
the prior occupant might be returned when trying to unpack an object
from the new pack.

Found-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
 cache.h       |    1 +
 fast-import.c |    1 +
 sha1_file.c   |    7 +++++++
 3 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/cache.h b/cache.h
index 8dcc53c..7f1a6e8 100644
--- a/cache.h
+++ b/cache.h
@@ -830,6 +830,7 @@ extern unsigned char* use_pack(struct packed_git *, struct pack_window **, off_t
 extern void close_pack_windows(struct packed_git *);
 extern void unuse_pack(struct pack_window **);
 extern void free_pack_by_name(const char *);
+extern void clear_delta_base_cache(void);
 extern struct packed_git *add_packed_git(const char *, int, int);
 extern const unsigned char *nth_packed_object_sha1(struct packed_git *, uint32_t);
 extern off_t nth_packed_object_offset(const struct packed_git *, uint32_t);
diff --git a/fast-import.c b/fast-import.c
index 1935206..03b13e0 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -945,6 +945,7 @@ static void end_packfile(void)
 {
 	struct packed_git *old_p = pack_data, *new_p;
 
+	clear_delta_base_cache();
 	if (object_count) {
 		char *idx_name;
 		int i;
diff --git a/sha1_file.c b/sha1_file.c
index 8868b80..d2dbc96 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1663,6 +1663,13 @@ static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
 	}
 }
 
+void clear_delta_base_cache(void)
+{
+	unsigned long p;
+	for (p = 0; p < MAX_DELTA_CACHE; p++)
+		release_delta_base_cache(&delta_base_cache[p])
+}
+
 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
 	void *base, unsigned long base_size, enum object_type type)
 {
-- 
1.6.2.rc0.186.g417c