packfile: move packfile store into object source

The packfile store is a member of `struct object_database`, which means
that we have a single store per database. This doesn't really make much
sense though: each source connected to the database has its own set of
packfiles, so there is a conceptual mismatch here. This hasn't really
caused much of a problem in the past, but with the advent of pluggable
object databases this is becoming more of a problem because some of the
sources may not even use packfiles in the first place.

Move the packfile store down by one level from the object database into
the object database source. This ensures that each source now has its
own packfile store, and we can eventually start to abstract it away
entirely so that the caller doesn't even know what kind of store it
uses.

Note that we only need to adjust a relatively small number of callers,
way less than one might expect. This is because most callers are using
`repo_for_each_pack()`, which handles enumeration of all packfiles that
exist in the repository. So for now, none of these callers need to be
adapted. The remaining callers that iterate through the packfiles
directly and that need adjustment are those that are a bit more tangled
with packfiles. These will be adjusted over time.

Note that this patch only moves the packfile store, and there is still a
bunch of functions that seemingly operate on a packfile store but that
end up iterating over all sources. These will be adjusted in subsequent
commits.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 81 insertions, 46 deletions

diff --git a/packfile.c b/packfile.c
index 3700612465..a0225cb2cb 100644
--- a/packfile.c
+++ b/packfile.c
@@ -357,12 +357,14 @@ static void scan_windows(struct packed_git *p,
 
 static int unuse_one_window(struct object_database *odb)
 {
+	struct odb_source *source;
 	struct packfile_list_entry *e;
 	struct packed_git *lru_p = NULL;
 	struct pack_window *lru_w = NULL, *lru_l = NULL;
 
-	for (e = odb->packfiles->packs.head; e; e = e->next)
-		scan_windows(e->pack, &lru_p, &lru_w, &lru_l);
+	for (source = odb->sources; source; source = source->next)
+		for (e = source->packfiles->packs.head; e; e = e->next)
+			scan_windows(e->pack, &lru_p, &lru_w, &lru_l);
 
 	if (lru_p) {
 		munmap(lru_w->base, lru_w->len);
@@ -528,15 +530,18 @@ static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struc
 
 static int close_one_pack(struct repository *r)
 {
+	struct odb_source *source;
 	struct packfile_list_entry *e;
 	struct packed_git *lru_p = NULL;
 	struct pack_window *mru_w = NULL;
 	int accept_windows_inuse = 1;
 
-	for (e = r->objects->packfiles->packs.head; e; e = e->next) {
-		if (e->pack->pack_fd == -1)
-			continue;
-		find_lru_pack(e->pack, &lru_p, &mru_w, &accept_windows_inuse);
+	for (source = r->objects->sources; source; source = source->next) {
+		for (e = source->packfiles->packs.head; e; e = e->next) {
+			if (e->pack->pack_fd == -1)
+				continue;
+			find_lru_pack(e->pack, &lru_p, &mru_w, &accept_windows_inuse);
+		}
 	}
 
 	if (lru_p)
@@ -987,7 +992,7 @@ static void prepare_pack(const char *full_name, size_t full_name_len,
 	if (strip_suffix_mem(full_name, &base_len, ".idx") &&
 	    !(data->source->midx && midx_contains_pack(data->source->midx, file_name))) {
 		char *trimmed_path = xstrndup(full_name, full_name_len);
-		packfile_store_load_pack(data->source->odb->packfiles,
+		packfile_store_load_pack(data->source->packfiles,
 					 trimmed_path, data->source->local);
 		free(trimmed_path);
 	}
@@ -1245,11 +1250,15 @@ void mark_bad_packed_object(struct packed_git *p, const struct object_id *oid)
 const struct packed_git *has_packed_and_bad(struct repository *r,
 					    const struct object_id *oid)
 {
-	struct packfile_list_entry *e;
+	struct odb_source *source;
+
+	for (source = r->objects->sources; source; source = source->next) {
+		struct packfile_list_entry *e;
+		for (e = source->packfiles->packs.head; e; e = e->next)
+			if (oidset_contains(&e->pack->bad_objects, oid))
+				return e->pack;
+	}
 
-	for (e = r->objects->packfiles->packs.head; e; e = e->next)
-		if (oidset_contains(&e->pack->bad_objects, oid))
-			return e->pack;
 	return NULL;
 }
 
@@ -2089,26 +2098,32 @@ static int find_pack_entry(struct repository *r,
 			   const struct object_id *oid,
 			   struct pack_entry *e)
 {
-	struct packfile_list_entry *l;
+	struct odb_source *source;
 
-	packfile_store_prepare(r->objects->packfiles);
+	/*
+	 * Note: `packfile_store_prepare()` prepares stores from all sources.
+	 * This will be fixed in a subsequent commit.
+	 */
+	packfile_store_prepare(r->objects->sources->packfiles);
 
-	for (struct odb_source *source = r->objects->sources; source; source = source->next)
+	for (source = r->objects->sources; source; source = source->next)
 		if (source->midx && fill_midx_entry(source->midx, oid, e))
 			return 1;
 
-	if (!r->objects->packfiles->packs.head)
-		return 0;
+	for (source = r->objects->sources; source; source = source->next) {
+		struct packfile_list_entry *l;
 
-	for (l = r->objects->packfiles->packs.head; l; l = l->next) {
-		struct packed_git *p = l->pack;
+		for (l = source->packfiles->packs.head; l; l = l->next) {
+			struct packed_git *p = l->pack;
 
-		if (!p->multi_pack_index && fill_pack_entry(oid, e, p)) {
-			if (!r->objects->packfiles->skip_mru_updates)
-				packfile_list_prepend(&r->objects->packfiles->packs, p);
-			return 1;
+			if (!p->multi_pack_index && fill_pack_entry(oid, e, p)) {
+				if (!source->packfiles->skip_mru_updates)
+					packfile_list_prepend(&source->packfiles->packs, p);
+				return 1;
+			}
 		}
 	}
+
 	return 0;
 }
 
@@ -2216,12 +2231,18 @@ int find_kept_pack_entry(struct repository *r,
 			 unsigned flags,
 			 struct pack_entry *e)
 {
-	struct packed_git **cache = packfile_store_get_kept_pack_cache(r->objects->packfiles, flags);
+	struct odb_source *source;
 
-	for (; *cache; cache++) {
-		struct packed_git *p = *cache;
-		if (fill_pack_entry(oid, e, p))
-			return 1;
+	for (source = r->objects->sources; source; source = source->next) {
+		struct packed_git **cache;
+
+		cache = packfile_store_get_kept_pack_cache(source->packfiles, flags);
+
+		for (; *cache; cache++) {
+			struct packed_git *p = *cache;
+			if (fill_pack_entry(oid, e, p))
+				return 1;
+		}
 	}
 
 	return 0;
@@ -2287,32 +2308,46 @@ int for_each_object_in_pack(struct packed_git *p,
 int for_each_packed_object(struct repository *repo, each_packed_object_fn cb,
 			   void *data, enum for_each_object_flags flags)
 {
-	struct packed_git *p;
+	struct odb_source *source;
 	int r = 0;
 	int pack_errors = 0;
 
-	repo->objects->packfiles->skip_mru_updates = true;
-	repo_for_each_pack(repo, p) {
-		if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
-			continue;
-		if ((flags & FOR_EACH_OBJECT_PROMISOR_ONLY) &&
-		    !p->pack_promisor)
-			continue;
-		if ((flags & FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS) &&
-		    p->pack_keep_in_core)
-			continue;
-		if ((flags & FOR_EACH_OBJECT_SKIP_ON_DISK_KEPT_PACKS) &&
-		    p->pack_keep)
-			continue;
-		if (open_pack_index(p)) {
-			pack_errors = 1;
-			continue;
+	odb_prepare_alternates(repo->objects);
+
+	for (source = repo->objects->sources; source; source = source->next) {
+		struct packfile_list_entry *e;
+
+		source->packfiles->skip_mru_updates = true;
+
+		for (e = packfile_store_get_packs(source->packfiles); e; e = e->next) {
+			struct packed_git *p = e->pack;
+
+			if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
+				continue;
+			if ((flags & FOR_EACH_OBJECT_PROMISOR_ONLY) &&
+			    !p->pack_promisor)
+				continue;
+			if ((flags & FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS) &&
+			    p->pack_keep_in_core)
+				continue;
+			if ((flags & FOR_EACH_OBJECT_SKIP_ON_DISK_KEPT_PACKS) &&
+			    p->pack_keep)
+				continue;
+			if (open_pack_index(p)) {
+				pack_errors = 1;
+				continue;
+			}
+
+			r = for_each_object_in_pack(p, cb, data, flags);
+			if (r)
+				break;
 		}
-		r = for_each_object_in_pack(p, cb, data, flags);
+
+		source->packfiles->skip_mru_updates = false;
+
 		if (r)
 			break;
 	}
-	repo->objects->packfiles->skip_mru_updates = false;
 
 	return r ? r : pack_errors;
 }