pack-bitmap: factor out 'bitmap_for_commit()'

A couple of callers within pack-bitmap.c duplicate logic to lookup a
given object id in the bitamps khash. Factor this out into a new
function, 'bitmap_for_commit()' to reduce some code duplication.

Make this new function non-static, since it will be used in later
commits from outside of pack-bitmap.c.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pack-bitmap.c

@@ -380,6 +380,16 @@ struct include_data {
 	struct bitmap *seen;
 };
 
+struct ewah_bitmap *bitmap_for_commit(struct bitmap_index *bitmap_git,
+				      struct commit *commit)
+{
+	khiter_t hash_pos = kh_get_oid_map(bitmap_git->bitmaps,
+					   commit->object.oid);
+	if (hash_pos >= kh_end(bitmap_git->bitmaps))
+		return NULL;
+	return lookup_stored_bitmap(kh_value(bitmap_git->bitmaps, hash_pos));
+}
+
 static inline int bitmap_position_extended(struct bitmap_index *bitmap_git,
 					   const struct object_id *oid)
 {
@@ -465,10 +475,10 @@ static void show_commit(struct commit *commit, void *data)
 
 static int add_to_include_set(struct bitmap_index *bitmap_git,
 			      struct include_data *data,
-			      const struct object_id *oid,
+			      struct commit *commit,
 			      int bitmap_pos)
 {
-	khiter_t hash_pos;
+	struct ewah_bitmap *partial;
 
 	if (data->seen && bitmap_get(data->seen, bitmap_pos))
 		return 0;
@@ -476,10 +486,9 @@ static int add_to_include_set(struct bitmap_index *bitmap_git,
 	if (bitmap_get(data->base, bitmap_pos))
 		return 0;
 
-	hash_pos = kh_get_oid_map(bitmap_git->bitmaps, *oid);
+	partial = bitmap_for_commit(bitmap_git, commit);
-	if (hash_pos < kh_end(bitmap_git->bitmaps)) {
+	if (partial) {
-		struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, hash_pos);
+		bitmap_or_ewah(data->base, partial);
-		bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 		return 0;
 	}
 
@@ -498,8 +507,7 @@ static int should_include(struct commit *commit, void *_data)
 						  (struct object *)commit,
 						  NULL);
 
-	if (!add_to_include_set(data->bitmap_git, data, &commit->object.oid,
+	if (!add_to_include_set(data->bitmap_git, data, commit, bitmap_pos)) {
-				bitmap_pos)) {
 		struct commit_list *parent = commit->parents;
 
 		while (parent) {
@@ -1282,10 +1290,10 @@ void test_bitmap_walk(struct rev_info *revs)
 {
 	struct object *root;
 	struct bitmap *result = NULL;
-	khiter_t pos;
 	size_t result_popcnt;
 	struct bitmap_test_data tdata;
 	struct bitmap_index *bitmap_git;
+	struct ewah_bitmap *bm;
 
 	if (!(bitmap_git = prepare_bitmap_git(revs->repo)))
 		die("failed to load bitmap indexes");
@@ -1297,12 +1305,9 @@ void test_bitmap_walk(struct rev_info *revs)
 		bitmap_git->version, bitmap_git->entry_count);
 
 	root = revs->pending.objects[0].item;
-	pos = kh_get_oid_map(bitmap_git->bitmaps, root->oid);
+	bm = bitmap_for_commit(bitmap_git, (struct commit *)root);
-
-	if (pos < kh_end(bitmap_git->bitmaps)) {
-		struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, pos);
-		struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 
+	if (bm) {
 		fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 			oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
 

pack-bitmap.h

@@ -78,6 +78,8 @@ uint32_t *create_bitmap_mapping(struct bitmap_index *bitmap_git,
 int rebuild_bitmap(const uint32_t *reposition,
 		   struct ewah_bitmap *source,
 		   struct bitmap *dest);
+struct ewah_bitmap *bitmap_for_commit(struct bitmap_index *bitmap_git,
+				      struct commit *commit);
 void bitmap_writer_select_commits(struct commit **indexed_commits,
 		unsigned int indexed_commits_nr, int max_bitmaps);
 void bitmap_writer_build(struct packing_data *to_pack);