Re: [PATCH/RFC 0/7] Pie-in-the-sky attempt to fix the early config

On Thu, Dec 08, 2016 at 04:35:56PM +0100, Johannes Schindelin wrote:

Great. Thanks for taking a stab at this.

It looks like a lot of that ugliness comes from passing around the "are we OK to peek at git-dir config" flag through the various pager-related calls. I don't think it would be bad to use a global for "we do not want a repo". After all, it's just modifying the _existing_ global for "are we in a repo". And I do not see that global going away anytime soon. Sometimes it's good to make incremental steps towards an end goal, but in this case it seems like we just pay the cost of the step without any real plan for reaping the benefit in the long term.

As an alternative, I also think it would be OK to just always have the pager config read from local repo, even for init/clone. In other words, to loosen the idea that git-init can _never_ look in the current git-dir, and declare that there is a stage before the command is initiated, and during which git may read local-repo config. Aliases would fall into this, too, so:

  git config --local alias.foo init
  git foo /some/other/dir

would work (as it must, because we cannot know that "foo" is "init" until we read the config!).

I have a feeling you may declare that too magical, but I think it's consistent and practical.

I assume you mean setting the CREATES_GIT_DIR flag here? I think it would apply to the dashed invocations, too. They strip off the "git-" and end up in handle_builtin() just like "git clone" does. I didn't test it, though.

Yeah, I did not read your discover function very carefully. Because I think the one thing we really don't want to do here is introduce a separate lookup process that is not shared by setup_git_directory(). The only sane path, I think, is to refactor setup_git_directory() to build on top of discover_git_directory(), which implies that the latter handles all of the cases.

We already have a config-caching system. If we went with a global "config_discover_refs", then I think the sequence for something like git-init would become:

  1. When git.c starts, config_discover_refs is set to "true". Pager and
     alias lookup may look in .git/config if it's available, even if
     they go through the configset cache.

  2. As soon as git-init starts, it disables config_discover_refs, and
     it flushes the config cache. Any configset lookups will now examine
     the reduced config.

  3. When git-init has set up the real repo it is operating on, it can
     reenable config_discover_refs (though it may not even need to; that
     flag probably wouldn't have any effect once we've entered the
     repository and have_git_dir() returns true).

Running t7006 I see a lot of old failures turned into successes, which is good (because running from a subdirectory now actually respects local pager config). The one failure looks like it is testing the wrong thing.

It is checking that we _don't_ respect a local core.pager in some cases, as a proxy for whether or not we are breaking things by doing setup too early. But the whole point of your series is to fix that, and respect the config without causing the setup breakage. After your patches, the proxy behavior and the failure case are disconnected. The test should be flipped, and ideally another one added that confirms we didn't actually run setup_git_directory(), but I'm not sure how to test that directly.

If caching happens at the config layer, then we'd probably only call this once anyway (or if we did call it again after a config flush, it would be a good sign that we should compute its value again).

-Peff