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Re: [PATCH 10/23] files_ref_store: put the packed files lock directly in this struct

On Wed, May 17, 2017 at 6:17 AM, Jeff King <peff@xxxxxxxx> wrote:
> On Wed, May 17, 2017 at 02:05:33PM +0200, Michael Haggerty wrote:
>> Instead of using a global `lock_file` instance for the main
>> "packed-refs" file and using a pointer in `files_ref_store` to keep
>> track of whether it is locked, embed the `lock_file` instance directly
>> in the `files_ref_store` struct and use the new
>> `is_lock_file_locked()` function to keep track of whether it is
>> locked. This keeps related data together and makes the main reference
>> store less of a special case.
> This made me wonder how we handle the locking for ref_stores besides the
> main one (e.g., for submodules). The lockfile structs have to remain
> valid for the length of the program. Previously those stores could have
> xcalloc()'d a lockfile and just leaked it. Now they'll need to xcalloc()
> and leak their whole structs.

+cc Brandon, who is eager to go down that road.

> I suspect the answer is "we don't ever lock anything except the main ref
> store because that is the only one we write to", so it doesn't matter
> anyway.
> -Peff

> @@ -102,7 +98,7 @@ static void clear_packed_ref_cache(struct files_ref_store *refs)
>        if (refs->packed) {
>                struct packed_ref_cache *packed_refs = refs->packed;
> -               if (refs->packlock)
> +               if (is_lock_file_locked(&refs->packlock))
>                        die("internal error: packed-ref cache cleared while locked");

I think the error message needs adjustment here as well? Maybe

     die("internal error: packed refs locked in cleanup");