Re: [PATCH v2 04/16] files-backend: replace *git_path*() with files_path()

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On Mon, Feb 20, 2017 at 6:23 PM, Michael Haggerty <mhagger@xxxxxxxxxxxx> wrote:
> On 02/16/2017 12:48 PM, Nguyễn Thái Ngọc Duy wrote:
>> This centralizes all path rewriting of files-backend.c in one place so
>> we have easier time removing the path rewriting later. There could be
>> some hidden indirect git_path() though, I didn't audit the code to the
>> bottom.
>
> Almost all of the calls to `files_path()` [1] take one of the following
> forms:
>
> * `files_path(refs, &sb, "packed-refs")`
> * `files_path(refs, &sb, "%s", refname)`
> * `files_path(refs, &sb, "logs/%s", refname)`
>
> (though sometimes `refname` is not the name of a reference but rather
> the name of a directory containing references, like "refs/heads").
>
> This suggests to me that it would be more natural to have three
> functions, `files_packed_refs_path()`, `files_loose_ref_path()`, and
> `files_reflog_path()`, with no `fmt` arguments. Aside from making the
> callers a bit simpler and the implementation of each of the three
> functions simpler (they wouldn't have to deal with variable argument
> lists), at the cost of needing three similar functions.
>
> But I think the split would also be advantageous from a design point of
> view. The relative path locations of loose reference files, reflog
> files, and the packed-refs file is kind of a coincidence, and it would
> be advantageous to encode that policy in three functions rather than
> continuing to spread knowledge of those assumptions around.
>
> It would also make it easier to switch to a new system of encoding
> reference names, for example so that reference names that differ only in
> case can be stored on a case-insensitive filesystem, or to store reflogs
> using a naming scheme that is not susceptible to D/F conflicts so that
> we can retain reflogs for deleted references.

I agree. I didn't see it clearly at the beginning (and made several
mistakes in earlier iterations) but as you have seen files_path() the
separation is pretty clear there. I was going to do it when
introducing the "linked worktree" backend. But since you pointed it
out, I'll update it in this series too.

> Michael
>
> [1] The only exception I see is one call `files_path(refs, &sb,
> "logs")`, which is a prelude to iterating over the reflog files. This is
> actually an example of the code giving us a hint that the design is
> wrong: if you iterate only over the directories under `git_path(logs)`,
> you miss the reflogs for worktree references.

Oh yes, I had to fix the reflog iterator [1] exactly for that :)

[1] https://public-inbox.org/git/20170217141908.18012-14-pclouds@xxxxxxxxx/T/#u
-- 
Duy




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