Re: [PATCHv2 5/8] fetching submodules: Respect `submodule.jobs` config option

[Eric Sunshine <ericsunshine@gmail.com>]

On Wed, Oct 28, 2015 at 7:21 PM, Stefan Beller <sbeller@google.com> wrote:
> This allows to configure fetching and updating in parallel
> without having the command line option.
>
> This moved the responsibility to determine how many parallel processes
> to start from builtin/fetch to submodule.c as we need a way to communicate
> "The user did not specify the number of parallel processes in the command
> line options" in the builtin fetch. The submodule code takes care of
> the precedence (CLI > config > default)
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index 391a0c3..785721a 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -2643,6 +2643,13 @@ submodule.<name>.ignore::
>         "--ignore-submodules" option. The 'git submodule' commands are not
>         affected by this setting.
>
> +submodule.jobs::
> +       This is used to determine how many submodules can be operated on in
> +       parallel. Specifying a positive integer allows up to that number
> +       of submodules being fetched in parallel. This is used in fetch
> +       and clone operations only. A value of 0 will give some reasonable
> +       default. The defaults may change with different versions of Git.

I'm not sure that "default" is the correct word here. When you talk
about a "default", you're normally explaining what happens when the
configuration is not provided. (In fact, the default number of jobs is
1, which you may want to document here).

>  tag.sort::
>         This variable controls the sort ordering of tags when displayed by
>         linkgit:git-tag[1]. Without the "--sort=<value>" option provided, the
> diff --git a/submodule-config.c b/submodule-config.c
> index 1cea404..07bdcdf 100644
> --- a/submodule-config.c
> +++ b/submodule-config.c
> @@ -32,6 +32,7 @@ enum lookup_type {
>
>  static struct submodule_cache cache;
>  static int is_cache_init;
> +static int parallel_jobs = -1;
>
>  static int config_path_cmp(const struct submodule_entry *a,
>                            const struct submodule_entry *b,
> @@ -235,6 +236,9 @@ static int parse_generic_submodule_config(const char *var,
>                                           const char *key,
>                                           const char *value)
>  {
> +       if (!strcmp(key, "jobs")) {
> +               parallel_jobs = strtol(value, NULL, 10);
> +       }

Style: unnecessary braces

Why does this allow a negative value? The documentation doesn't
mention anything about it.

>         return 0;
>  }
>
> diff --git a/submodule.c b/submodule.c
> index 0257ea3..188ba02 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -752,6 +752,11 @@ int fetch_populated_submodules(const struct argv_array *options,
>         argv_array_push(&spf.args, "--recurse-submodules-default");
>         /* default value, "--submodule-prefix" and its value are added later */
>
> +       if (max_parallel_jobs < 0)
> +               max_parallel_jobs = config_parallel_submodules();
> +       if (max_parallel_jobs < 0)
> +               max_parallel_jobs = 1;

run_process_parallel() itself specially handles max_parallel_jobs==0,
so you don't need to consider it here. Okay.

> +
>         calculate_changed_submodule_paths();
>         run_processes_parallel(max_parallel_jobs,
>                                get_next_submodule,
> diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
> index 1b4ce69..5c3579c 100755
> --- a/t/t5526-fetch-submodules.sh
> +++ b/t/t5526-fetch-submodules.sh
> @@ -470,4 +470,18 @@ test_expect_success "don't fetch submodule when newly recorded commits are alrea
>         test_i18ncmp expect.err actual.err
>  '
>
> +test_expect_success 'fetching submodules respects parallel settings' '
> +       git config fetch.recurseSubmodules true &&
> +       (
> +               cd downstream &&
> +               GIT_TRACE=$(pwd)/trace.out git fetch --jobs 7 &&
> +               grep "7 children" trace.out &&
> +               git config submodule.jobs 8 &&
> +               GIT_TRACE=$(pwd)/trace.out git fetch &&
> +               grep "8 children" trace.out &&
> +               GIT_TRACE=$(pwd)/trace.out git fetch --jobs 9 &&
> +               grep "9 children" trace.out
> +       )
> +'

Not specifically related to this test, but maybe add tests to check
cases when --jobs is not specified, and --jobs=1?

> +
>  test_done
> --
> 2.5.0.281.g4ed9cdb
>