Re: [PATCH v2 05/10] 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>
> ---
>  builtin/fast-import.c  |  37 ++++++++------
>  builtin/grep.c         |   6 ++-
>  builtin/index-pack.c   |   2 +-
>  builtin/pack-objects.c |  96 +++++++++++++++++++------------------
>  http.c                 |   2 +-
>  midx.c                 |   5 +-
>  odb.c                  |  36 +++++++-------
>  odb.h                  |   6 +--
>  odb/streaming.c        |   9 ++--
>  packfile.c             | 127 +++++++++++++++++++++++++++++++------------------
>  packfile.h             |  62 ++++++++++++++++++++----
>  11 files changed, 243 insertions(+), 145 deletions(-)
>
> diff --git a/builtin/fast-import.c b/builtin/fast-import.c
> index 7849005ccb..b8a7757cfd 100644
> --- a/builtin/fast-import.c
> +++ b/builtin/fast-import.c
> @@ -900,7 +900,7 @@ static void end_packfile(void)
>  		idx_name = keep_pack(create_index());
>  
>  		/* Register the packfile with core git's machinery. */
> -		new_p = packfile_store_load_pack(pack_data->repo->objects->packfiles,
> +		new_p = packfile_store_load_pack(pack_data->repo->objects->sources->packfiles,
>  						 idx_name, 1);
>  		if (!new_p)
>  			die(_("core Git rejected index %s"), idx_name);
> @@ -955,7 +955,7 @@ static int store_object(
>  	struct object_id *oidout,
>  	uintmax_t mark)
>  {
> -	struct packfile_store *packs = the_repository->objects->packfiles;
> +	struct odb_source *source;
>  	void *out, *delta;
>  	struct object_entry *e;
>  	unsigned char hdr[96];
> @@ -979,7 +979,11 @@ static int store_object(
>  	if (e->idx.offset) {
>  		duplicate_count_by_type[type]++;
>  		return 1;
> -	} else if (packfile_list_find_oid(packfile_store_get_packs(packs), &oid)) {
> +	}
> +
> +	for (source = the_repository->objects->sources; source; source = source->next) {
> +		if (!packfile_list_find_oid(packfile_store_get_packs(source->packfiles), &oid))
> +			continue;
>  		e->type = type;
>  		e->pack_id = MAX_PACK_ID;
>  		e->idx.offset = 1; /* just not zero! */
> @@ -1096,10 +1100,10 @@ static void truncate_pack(struct hashfile_checkpoint *checkpoint)
>  
>  static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
>  {
> -	struct packfile_store *packs = the_repository->objects->packfiles;
>  	size_t in_sz = 64 * 1024, out_sz = 64 * 1024;
>  	unsigned char *in_buf = xmalloc(in_sz);
>  	unsigned char *out_buf = xmalloc(out_sz);
> +	struct odb_source *source;
>  	struct object_entry *e;
>  	struct object_id oid;
>  	unsigned long hdrlen;
> @@ -1179,24 +1183,29 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
>  	if (e->idx.offset) {
>  		duplicate_count_by_type[OBJ_BLOB]++;
>  		truncate_pack(&checkpoint);
> +		goto out;
> +	}
>  
> -	} else if (packfile_list_find_oid(packfile_store_get_packs(packs), &oid)) {
> +	for (source = the_repository->objects->sources; source; source = source->next) {
> +		if (!packfile_list_find_oid(packfile_store_get_packs(source->packfiles), &oid))
> +			continue;
>  		e->type = OBJ_BLOB;
>  		e->pack_id = MAX_PACK_ID;
>  		e->idx.offset = 1; /* just not zero! */
>  		duplicate_count_by_type[OBJ_BLOB]++;
>  		truncate_pack(&checkpoint);
> -
> -	} else {
> -		e->depth = 0;
> -		e->type = OBJ_BLOB;
> -		e->pack_id = pack_id;
> -		e->idx.offset = offset;
> -		e->idx.crc32 = crc32_end(pack_file);
> -		object_count++;
> -		object_count_by_type[OBJ_BLOB]++;
> +		goto out;
>  	}
>  
> +	e->depth = 0;
> +	e->type = OBJ_BLOB;
> +	e->pack_id = pack_id;
> +	e->idx.offset = offset;
> +	e->idx.crc32 = crc32_end(pack_file);
> +	object_count++;
> +	object_count_by_type[OBJ_BLOB]++;
> +
> +out:
>  	free(in_buf);
>  	free(out_buf);
>  }
> diff --git a/builtin/grep.c b/builtin/grep.c
> index 53cccf2d25..4855b871dd 100644
> --- a/builtin/grep.c
> +++ b/builtin/grep.c
> @@ -1213,8 +1213,12 @@ int cmd_grep(int argc,
>  		 */
>  		if (recurse_submodules)
>  			repo_read_gitmodules(the_repository, 1);
> +		/*
> +		 * Note: `packfile_store_prepare()` prepares stores from all
> +		 * sources. This will be fixed in a subsequent commit.