packfile: add all_packs list

If a repo contains a multi-pack-index, then the packed_git list
does not contain the packfiles that are covered by the multi-pack-index.
This is important for doing object lookups, abbreviations, and
approximating object count. However, there are many operations that
really want to iterate over all packfiles.

Create a new 'all_packs' linked list that contains this list, starting
with the packfiles in the multi-pack-index and then continuing along
the packed_git linked list.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

midx.c

@@ -197,7 +197,7 @@ static void close_midx(struct multi_pack_index *m)
 	FREE_AND_NULL(m->pack_names);
 }
 
-static int prepare_midx_pack(struct multi_pack_index *m, uint32_t pack_int_id)
+int prepare_midx_pack(struct multi_pack_index *m, uint32_t pack_int_id)
 {
 	struct strbuf pack_name = STRBUF_INIT;
 

midx.h

@@ -32,6 +32,7 @@ struct multi_pack_index {
 };
 
 struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local);
+int prepare_midx_pack(struct multi_pack_index *m, uint32_t pack_int_id);
 int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result);
 struct object_id *nth_midxed_object_oid(struct object_id *oid,
 					struct multi_pack_index *m,

object-store.h

@@ -129,6 +129,12 @@ struct raw_object_store {
 	/* A most-recently-used ordered version of the packed_git list. */
 	struct list_head packed_git_mru;
 
+	/*
+	 * A linked list containing all packfiles, starting with those
+	 * contained in the multi_pack_index.
+	 */
+	struct packed_git *all_packs;
+
 	/*
 	 * A fast, rough count of the number of objects in the repository.
 	 * These two fields are not meant for direct access. Use

packfile.c

@@ -972,6 +972,9 @@ static void prepare_packed_git(struct repository *r)
 		prepare_packed_git_one(r, alt->path, 0);
 	}
 	rearrange_packed_git(r);
+
+	r->objects->all_packs = NULL;
+
 	prepare_packed_git_mru(r);
 	r->objects->packed_git_initialized = 1;
 }
@@ -995,6 +998,30 @@ struct multi_pack_index *get_multi_pack_index(struct repository *r)
 	return r->objects->multi_pack_index;
 }
 
+struct packed_git *get_all_packs(struct repository *r)
+{
+	prepare_packed_git(r);
+
+	if (!r->objects->all_packs) {
+		struct packed_git *p = r->objects->packed_git;
+		struct multi_pack_index *m;
+
+		for (m = r->objects->multi_pack_index; m; m = m->next) {
+			uint32_t i;
+			for (i = 0; i < m->num_packs; i++) {
+				if (!prepare_midx_pack(m, i)) {
+					m->packs[i]->next = p;
+					p = m->packs[i];
+				}
+			}
+		}
+
+		r->objects->all_packs = p;
+	}
+
+	return r->objects->all_packs;
+}
+
 struct list_head *get_packed_git_mru(struct repository *r)
 {
 	prepare_packed_git(r);

packfile.h

@@ -51,6 +51,7 @@ extern void install_packed_git(struct repository *r, struct packed_git *pack);
 struct packed_git *get_packed_git(struct repository *r);
 struct list_head *get_packed_git_mru(struct repository *r);
 struct multi_pack_index *get_multi_pack_index(struct repository *r);
+struct packed_git *get_all_packs(struct repository *r);
 
 /*
  * Give a rough count of objects in the repository. This sacrifices accuracy