1. 19 Aug, 2015 1 commit
    • Heiko Voigt's avatar
      submodule: implement a config API for lookup of .gitmodules values · 959b5455
      Heiko Voigt authored
      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's avatarHeiko Voigt <hvoigt@hvoigt.net>
      Signed-off-by: Stefan Beller's avatarStefan Beller <sbeller@google.com>
      Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
      959b5455