Re: [PATCH 01/15] string_list: add string_list_duplicate

From: Stefan Beller <sbeller@google.com>
Date: Apr 27, 2016, 23:24 UTC
Message-ID: <CAGZ79kYRhk8bH7+rGRjfvwk=HHy8=Yfg_P54pp8Goeb-bO1wSw@mail.gmail.com>
In-Reply-To: <xmqqbn4u7ibp.fsf@gitster.mtv.corp.google.com>

On Wed, Apr 27, 2016 at 4:17 PM, Junio C Hamano <gitster@pobox.com> wrote:

Show 11 quoted lines

> Stefan Beller <sbeller@google.com> writes:
>
>> Another way to corrupt it is to change the configuration (e.g. add
>> things to the config hashmap such that it reallocates and grows).
>
> You're right.  But doesn't it hint that there is a deeper problem?
>
> By making a copy and keeping it, you would hold onto a stale value
> and would not see the result of updates you yourself make to the
> system.
>

In this case the value doesn't go stale. We do not change "submodule.defaultGroup", but only new submodule.$NAME.url and such. The memory for accessing it goes stale, so in this case it is okay. I don't think we want to see repeated calls to git_config_get_value_multi like :

        if (!pathspec.nr && git_config_get_value_multi(
                        "submodule.defaultGroup")) {
                gitmodules_config();
                for (i = 0; i < list.nr; i++) {
                        const struct submodule *sub =
                                submodule_from_path(null_sha1,
                                                    list.entries[i]->name);
                        group =
git_config_get_value_multi("submodule.defaultGroup")
                        if (submodule_in_group(group, sub))
                                init_submodule(list.entries[i]->name,
prefix, quiet);
                }
        }

Maybe I am overestimating the cost of git_config_get_value_multi, so it is no problem?

Thanks, Stefan