Re: [PATCH 4/6] object-file: generalize counting objects

> Generalize the function introduced in the preceding commit to not only
> be able to approximate the number of loose objects, but to also provide
> an accurate count. The behaviour can be toggled via a new flag.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  builtin/gc.c  |  5 +++--
>  object-file.c | 58 +++++++++++++++++++++++++++++++++++++---------------------
>  object-file.h |  5 +++--
>  odb.h         |  9 +++++++++
>  4 files changed, 52 insertions(+), 25 deletions(-)
>
> diff --git a/builtin/gc.c b/builtin/gc.c
> index a08c7554cb..3a64d28da8 100644
> --- a/builtin/gc.c
> +++ b/builtin/gc.c
> @@ -474,8 +474,9 @@ static int too_many_loose_objects(int limit)
>  	int auto_threshold = DIV_ROUND_UP(limit, 256) * 256;
>  	unsigned long loose_count;
>  
> -	if (odb_source_loose_approximate_object_count(the_repository->objects->sources,
> -						      &loose_count) < 0)
> +	if (odb_source_loose_count_objects(the_repository->objects->sources,
> +					   ODB_COUNT_OBJECTS_APPROXIMATE,
> +					   &loose_count) < 0)
>  		return 0;
>  
>  	return loose_count > auto_threshold;
> diff --git a/object-file.c b/object-file.c
> index da67e3c9ff..d35cec201f 100644
> --- a/object-file.c
> +++ b/object-file.c
> @@ -1868,40 +1868,56 @@ int odb_source_loose_for_each_object(struct odb_source *source,
>  					     NULL, NULL, &data);
>  }
>  
> -int odb_source_loose_approximate_object_count(struct odb_source *source,
> -					      unsigned long *out)
> +static int count_loose_object(const struct object_id *oid UNUSED,
> +			      struct object_info *oi UNUSED,
> +			      void *payload)
> +{
> +	unsigned long *count = payload;
> +	(*count)++;
> +	return 0;
> +}
> +
> +int odb_source_loose_count_objects(struct odb_source *source,
> +				   enum odb_count_objects_flags flags,
> +				   unsigned long *out)
>  {
>  	const unsigned hexsz = source->odb->repo->hash_algo->hexsz - 2;
> -	unsigned long count = 0;
> -	struct dirent *ent;
>  	char *path = NULL;
>  	DIR *dir = NULL;
>  	int ret;
>  
> -	path = xstrfmt("%s/17", source->path);
> +	if (flags & ODB_COUNT_OBJECTS_APPROXIMATE) {
> +		unsigned long count = 0;
> +		struct dirent *ent;
>  
> -	dir = opendir(path);
> -	if (!dir) {
> -		if (errno == ENOENT) {
> -			*out = 0;
> -			ret = 0;
> +		path = xstrfmt("%s/17", source->path);
> +
> +		dir = opendir(path);
> +		if (!dir) {
> +			if (errno == ENOENT) {
> +				*out = 0;
> +				ret = 0;
> +				goto out;
> +			}
> +
> +			ret = error_errno("cannot open object shard '%s'", path);
>  			goto out;
>  		}
>  
> -		ret = error_errno("cannot open object shard '%s'", path);
> -		goto out;
> -	}
> +		while ((ent = readdir(dir)) != NULL) {
> +			if (strspn(ent->d_name, "0123456789abcdef") != hexsz ||
> +			    ent->d_name[hexsz] != '\0')
> +				continue;
> +			count++;
> +		}
>  
> -	while ((ent = readdir(dir)) != NULL) {
> -		if (strspn(ent->d_name, "0123456789abcdef") != hexsz ||
> -		    ent->d_name[hexsz] != '\0')
> -			continue;
> -		count++;
> +		*out = count * 256;
> +		ret = 0;
> +	} else {
> +		ret = odb_source_loose_for_each_object(source, NULL, count_loose_object,
> +						       out, 0);

>  	}
>  
> -	*out = count * 256;
> -	ret = 0;
> -
>  out:
>  	if (dir)
>  		closedir(dir);
> diff --git a/object-file.h b/object-file.h
> index b870ea9fa8..f8d8805a18 100644
> --- a/object-file.h
> +++ b/object-file.h
> @@ -149,8 +149,9 @@ int odb_source_loose_for_each_object(struct odb_source *source,
>   *
>   * Returns 0 on success, a negative error code otherwise.
>   */
> -int odb_source_loose_approximate_object_count(struct odb_source *source,
> -					      unsigned long *out);
> +int odb_source_loose_count_objects(struct odb_source *source,
> +				   enum odb_count_objects_flags flags,
> +				   unsigned long *out);
>  
>  /**
>   * format_object_header() is a thin wrapper around s xsnprintf() that
> diff --git a/odb.h b/odb.h
> index 7a583e3873..e6057477f6 100644
> --- a/odb.h
> +++ b/odb.h
> @@ -500,6 +500,15 @@ int odb_for_each_object(struct object_database *odb,
>  			void *cb_data,
>  			unsigned flags);
>  
> +enum odb_count_objects_flags {
> +	/*
> +	 * Instead of providing an accurate count, allow the number of objects
> +	 * to be approximated. Details of how this approximation works are
> +	 * subject to the specific source's implementation.
> +	 */
> +	ODB_COUNT_OBJECTS_APPROXIMATE = (1 << 0),
> +};
> +
>  enum {
>  	/*
>  	 * By default, `odb_write_object()` does not actually write anything
>
> -- 
> 2.53.0.880.g73c4285caa.dirty
>
>