Re: [PATCH v2 04/17] odb/source-packed: store pointer to "files" instead of generic source

[Justin Tobler <jltobler@gmail.com>]

On 26/06/09 10:50AM, Patrick Steinhardt wrote:
> The `struct odb_source_packed` holds a pointer to its owning parent
> source. The way that Git is currently structured, this parent is always
> the "files" source. In subsequent commits we're going to detangle that
> so that the "packed" source doesn't have any owning parent source at
> all, which makes it usable as a completely standalone source.

Out of curiousity, `struct odb_source_loose` also stores a similar to
pointer to its owning parent. Is the plan to also eventually do the same
there?

> Detangling this mess is somewhat intricate though, and is made even more
> intricate because it's not always clear which kind of source one is
> holding at a specific point in time -- either the parent "files" source,
> or the child "packed" source.
> 
> Make this relationship more explicit by storing a pointer to the "files"
> source instead of storing a pointer to a generic `struct odb_source`.
> This will help make subsequent steps a bit clearer.
> 
> Note that this is a temporary step, only. At the end of this series
> we will have dropped the parent pointer completely.

Ok, so IIUC the eventual goal is to get rid of the pointer entirely, but
for now we are just making its concrete type explicit without having to
downcast. It's not immediately obvious to me how this step gets us
closer to that goal, but that may become more obvious in the next
patches. :)

> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  odb/source-files.c  |  2 +-
>  odb/source-packed.c |  4 ++--
>  odb/source-packed.h |  4 ++--
>  packfile.c          | 12 ++++++------
>  4 files changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/odb/source-files.c b/odb/source-files.c
> index 191562f316..e04525fb08 100644
> --- a/odb/source-files.c
> +++ b/odb/source-files.c
> @@ -269,7 +269,7 @@ struct odb_source_files *odb_source_files_new(struct object_database *odb,
>  	CALLOC_ARRAY(files, 1);
>  	odb_source_init(&files->base, odb, ODB_SOURCE_FILES, path, local);
>  	files->loose = odb_source_loose_new(odb, path, local);
> -	files->packed = odb_source_packed_new(&files->base);
> +	files->packed = odb_source_packed_new(files);
>  
>  	files->base.free = odb_source_files_free;
>  	files->base.close = odb_source_files_close;
> diff --git a/odb/source-packed.c b/odb/source-packed.c
> index 1e94b47ea0..12e785be48 100644
> --- a/odb/source-packed.c
> +++ b/odb/source-packed.c
> @@ -1,11 +1,11 @@
>  #include "git-compat-util.h"
>  #include "odb/source-packed.h"
>  
> -struct odb_source_packed *odb_source_packed_new(struct odb_source *source)
> +struct odb_source_packed *odb_source_packed_new(struct odb_source_files *parent)
>  {
>  	struct odb_source_packed *store;
>  	CALLOC_ARRAY(store, 1);
> -	store->source = source;
> +	store->files = parent;
>  	strmap_init(&store->packs_by_path);
>  	return store;
>  }
> diff --git a/odb/source-packed.h b/odb/source-packed.h
> index 327be4ad65..3c2d229a17 100644
> --- a/odb/source-packed.h
> +++ b/odb/source-packed.h
> @@ -9,7 +9,7 @@
>   * A store that manages packfiles for a given object database.
>   */
>  struct odb_source_packed {
> -	struct odb_source *source;
> +	struct odb_source_files *files;

The rest of this patch updates the callsites accordingly and looks
correct.

-Justin