On Mon, Jun 15, 2015 at 5:06 PM, Heiko Voigt <hvoigt@xxxxxxxxxx> wrote:
> In a superproject some commands need to interact with submodules. They
> need to query values from the .gitmodules file either from the worktree
> of from certain revisions. At the moment this is quite hard since a
> caller would need to read the .gitmodules file from the history and then
> parse the values. We want to provide an API for this so we have one
> place to get values from .gitmodules from any revision (including the
> worktree).
>
> The API is realized as a cache which allows us to lazily read
> .gitmodules configurations by commit into a runtime cache which can then
> be used to easily lookup values from it. Currently only the values for
> path or name are stored but it can be extended for any value needed.
>
> It is expected that .gitmodules files do not change often between
> commits. Thats why we lookup the .gitmodules sha1 from a commit and then
> either lookup an already parsed configuration or parse and cache an
> unknown one for each sha1. The cache is lazily build on demand for each
> requested commit.
>
> This cache can be used for all purposes which need knowledge about
> submodule configurations. Example use cases are:
>
> * Recursive submodule checkout needs to lookup a submodule name from
> its path when a submodule first appears. This needs be done before
> this configuration exists in the worktree.
>
> * The implementation of submodule support for 'git archive' needs to
> lookup the submodule name to generate the archive when given a
> revision that is not checked out.
>
> * 'git fetch' when given the --recurse-submodules=on-demand option (or
> configuration) needs to lookup submodule names by path from the
> database rather than reading from the worktree. For new submodule it
> needs to lookup the name from its path to allow cloning new
> submodules into the .git folder so they can be checked out without
> any network interaction when the user does a checkout of that
> revision.
>
> Signed-off-by: Heiko Voigt <hvoigt@xxxxxxxxxx>
> ---
> .gitignore | 1 +
> Documentation/technical/api-submodule-config.txt | 46 +++
> Makefile | 2 +
> submodule-config.c | 445 +++++++++++++++++++++++
> submodule-config.h | 27 ++
> submodule.c | 1 +
> submodule.h | 1 +
> t/t7411-submodule-config.sh | 85 +++++
> test-submodule-config.c | 66 ++++
> 9 files changed, 674 insertions(+)
> create mode 100644 Documentation/technical/api-submodule-config.txt
> create mode 100644 submodule-config.c
> create mode 100644 submodule-config.h
> create mode 100755 t/t7411-submodule-config.sh
> create mode 100644 test-submodule-config.c
Instead of test-submodule-config.c to test this new module, it could
be useful to implement these as extensions to rev-parse:
git rev-parse --submodule-name [<ref>:]<path>
git rev-parse --submodule-path [<ref>:]<name>
git rev-parse --submodule-url [<ref>:]<name>
git rev-parse --submodule-ignore [<ref>:]<name>
git rev-parse --submodule-recurse [<ref>:]<name>
Has this already been considered and rejected for some reason?
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