Re: [PATCH 1/6] path-walk: introduce an object walk by path

From: Derrick Stolee <stolee@gmail.com>
Date: Nov 1, 2024, 13:44 UTC
Message-ID: <541b89c7-5e4b-4251-a8e7-3a9cde381064@gmail.com>
In-Reply-To: <CAOLa=ZQnEL7i=QbqjHYjpjWv_uhG=u+1w1FUKTMgkfNYd3fefg@mail.gmail.com>

On 11/1/24 9:12 AM, karthik nayak wrote:

Show 20 quoted lines

> "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> From: Derrick Stolee <stolee@gmail.com>
>>
>> The walk_objects_by_path() method initializes these structures and
>> starts walking commits from the given rev_info struct. The commits are
>> used to find the list of root trees which populate the start of our
>> depth-first search.
> 
> Isn't this more of breadth-first search? Reading through the code, the
> algorithm seems something like:
> 
> - For each commit in list of commits (from rev_info)
>    - Tackle each root tree, add root path to the stack.
> - For each path in stack left
>    - Call the callback provided by client.
>    - Find all its first level children, add each to the stack.
> 
> So wouldn't this go through the tree in level by level basis? Making it
> a BFS?

While we are adding all children to the stack, we only pop off the top of the stack, making it a DFS. (We do visit the paths in reverse- lexicographic order, though.)

To make it a BFS, we would need to visit the paths in the order they are added to the list. Instead, we visit them in Last-In First-Out order.

I initially had built it as a BFS, but ran into memory issues when running it on very large repos.

Thanks, -Stolee