Re: [PATCH 04/14] object-file: introduce function to iterate through objects

> We have multiple divergent interfaces to iterate through objects of a
> specific backend:
>
>   - `for_each_loose_object()` yields all loose objects.
>
>   - `for_each_packed_object()` (somewhat obviously) yields all packed
>     objects.
>
> These functions have different function signatures, which makes it hard
> to create a common abstraction layer that covers both of these.
>
> Introduce a new function `odb_source_loose_for_each_object()` to plug
> this gap. This function doesn't take any data specific to loose objects,
> but instead it accepts a `struct object_info` that will be populated the
> exact same as if `odb_source_loose_read_object()` was called.
>
> The benefit of this new interface is that we can continue to pass
> backend-specific data, as `struct object_info` contains a union for
> these exact use cases. This will allow us to unify how we iterate
> through objects across both loose and packed objects in a subsequent
> commit.
>
> The `for_each_loose_object()` function continues to exist for now, but
> it will be removed at the end of this patch series.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  object-file.c | 41 +++++++++++++++++++++++++++++++++++++++++
>  object-file.h | 11 +++++++++++
>  odb.h         | 12 ++++++++++++
>  3 files changed, 64 insertions(+)
>
> diff --git a/object-file.c b/object-file.c
> index a651129426..65e730684b 100644
> --- a/object-file.c
> +++ b/object-file.c
> @@ -1801,6 +1801,47 @@ int for_each_loose_object(struct object_database *odb,
>  	return 0;
>  }
>
> +struct for_each_object_wrapper_data {
> +	struct odb_source *source;
> +	struct object_info *oi;
> +	odb_for_each_object_cb cb;
> +	void *cb_data;
> +};
> +
> +static int for_each_object_wrapper_cb(const struct object_id *oid,
> +				      const char *path,
> +				      void *cb_data)
> +{
> +	struct for_each_object_wrapper_data *data = cb_data;
> +	if (data->oi &&
> +	    read_object_info_from_path(data->source, path, oid, data->oi, 0) < 0)
> +			return -1;
> +	return data->cb(oid, data->oi, data->cb_data);
> +}