Re: [PATCH v2 05/10] cache-tree: implement cache_tree_find_path()

[Derrick Stolee <derrickstolee@github.com>]

On 5/19/2022 4:14 PM, Junio C Hamano wrote:
> "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> +struct cache_tree *cache_tree_find_path(struct cache_tree *it, const char *path)
>> +{
>> +	const char *slash;
>> +	int namelen;
>> +	struct cache_tree_sub *down;
>> +
>> +	if (!it)
>> +		return NULL;
>> +	slash = strchrnul(path, '/');
>> +	namelen = slash - path;
>> +	it->entry_count = -1;
>> +	if (!*slash) {
>> +		int pos;
>> +		pos = cache_tree_subtree_pos(it, path, namelen);
>> +		if (0 <= pos)
>> +			return it->down[pos]->cache_tree;
>> +		return NULL;
>> +	}
>> +	down = find_subtree(it, path, namelen, 0);
>> +	if (down)
>> +		return cache_tree_find_path(down->cache_tree, slash + 1);
>> +	return NULL;
>> +}
> 
> The tail recursion (and the one in the orginal) may want to be
> trivially converted to iteration with "goto".

Good idea!
 
> It is somewhat surprising that we didn't have any external interface
> to expose a sub-part of the cache_tree at all so far.  It may be
> because the API was so well designed that the abstraction did not
> have to be exposed.  I dunno.

I think the abstraction definitely fit the shape of its consumers
pretty perfectly. I wonder if having a method like this will make
us think of new ways to use the cache tree for other things.

Thanks,
-Stolee