On 6/7/2022 6:09 PM, Junio C Hamano wrote:
> "Derrick Stolee via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
>
>> +int branch_checked_out(const char *refname, char **path)
>> +{
>> + struct worktree **worktrees = get_worktrees();
>> + const struct worktree *wt = find_shared_symref(worktrees, "HEAD", refname);
>> + int result = wt && !wt->is_bare;
>> +
>> + if (result && path)
>> + *path = xstrdup(wt->path);
>> +
>> + free_worktrees(worktrees);
>> + return result;
>> +}
>
> Don't you plan to call this repeatedly from the for_each_deco
> iteration? I am wondering if it should take the result of
> get_worktrees() and reuse the result of get_worktrees(), instead of
> enumerating the list of worktrees and freeing for each of the
> branches you need to inspect.
Sorry, you had mentioned this in v1 and I just forgot to fix this.
> There also was another topic
>
> https://lore.kernel.org/git/pull.1266.v2.git.git.1652690501963.gitgitgadget@xxxxxxxxx/
>
> that was triggered by find_shared_symref() being relatively
> heavy-weight, which suggests a more involved refactoring.
>
> I wonder if we rather want to rewrite find_shared_symref() *not* to
> take the target parameter at all, and instead introduce a new
> function that takes a worktree, and report the branch that is
> checked out (or being operated on via rebase or bisect). Then we
> can
>
> - create a strset out of its result, i.e. set of branches that
> should not be touched;
>
> - iterate over refs that point into the history being rebased
> (using for_each_decoration()), and consult that strset to see if
> any of them is being rewritten.
>
> With the API of find_shared_symref(), we'd need to iterate over all
> worktrees for each decoration. With such a restructuring, we can
> iterate over all worktrees just once, and match the result with
> decoration, so the problem becomes O(N)+O(M) and not O(N*M) for
> number of worktrees N and number of decorations M.
Yes, that's a good plan. I'll take a look.
Thanks,
-Stolee
