Re: [RFH] two and half potential fixlets to the in-core index handling

[Linus Torvalds <torvalds@linux-foundation.org>]

On Sat, 23 Aug 2008, Junio C Hamano wrote:
> 
> A hacky solution I have in the attached patch is to waste an xmalloc(1)
> and store it there when o->result is created, and also make
> read_from_index() pay attention to the cache_nr and the cache_changed
> bit. I think it is the safest and minimum fix.

Hmm. Wouldn't it be nicer to just add another bit to istate? We have the 
space already, since we already have a bitfield there, with just one bit 
used?

Something like this..

Untested. Of course.

			Linus

---
 cache.h        |    3 ++-
 read-cache.c   |    4 +++-
 unpack-trees.c |    1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/cache.h b/cache.h
index 68ce6e6..6e41ec4 100644
--- a/cache.h
+++ b/cache.h
@@ -222,7 +222,8 @@ struct index_state {
 	struct cache_tree *cache_tree;
 	time_t timestamp;
 	void *alloc;
-	unsigned name_hash_initialized : 1;
+	unsigned name_hash_initialized : 1,
+		 initialized : 1;
 	struct hash_table name_hash;
 };
 
diff --git a/read-cache.c b/read-cache.c
index 2c03ec3..35fec46 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1155,7 +1155,7 @@ int read_index_from(struct index_state *istate, const char *path)
 	size_t mmap_size;
 
 	errno = EBUSY;
-	if (istate->alloc)
+	if (istate->initialized)
 		return istate->cache_nr;
 
 	errno = ENOENT;
@@ -1195,6 +1195,7 @@ int read_index_from(struct index_state *istate, const char *path)
 	 * index size
 	 */
 	istate->alloc = xmalloc(estimate_cache_size(mmap_size, istate->cache_nr));
+	istate->initialized = 1;
 
 	src_offset = sizeof(*hdr);
 	dst_offset = 0;
@@ -1247,6 +1248,7 @@ int discard_index(struct index_state *istate)
 	cache_tree_free(&(istate->cache_tree));
 	free(istate->alloc);
 	istate->alloc = NULL;
+	istate->initialized = 0;
 
 	/* no need to throw away allocated active_cache */
 	return 0;
diff --git a/unpack-trees.c b/unpack-trees.c
index cba0aca..ef21c62 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -376,6 +376,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	state.refresh_cache = 1;
 
 	memset(&o->result, 0, sizeof(o->result));
+	o->result.initialized = 1;
 	if (o->src_index)
 		o->result.timestamp = o->src_index->timestamp;
 	o->merge_size = len;