Re: [PATCH v2 6/6] commit-graph: add repo arg to graph readers

[Jonathan Tan <jonathantanmy@google.com>]

> > -	if (!core_commit_graph)
> > +	if (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
> > +	    !config_value)
> > +		/*
> > +		 * This repository is not configured to use commit graphs, so
> > +		 * do not load one. (But report commit_graph_attempted anyway
> > +		 * so that commit graph loading is not attempted again for this
> > +		 * repository.)
> > +		 */
> 
> I reacted first to complain about this extra config lookup, but it is 
> only run once per repository, so that should be fine.

Thanks for checking. It is indeed run at most once per repository, and
only if a commit graph is requested - the same as the current code.

> The tests below form a decently-large patch on their own. Perhaps split 
> them out so it is easier to know that we have some interesting things to 
> check here.

The patch is 168+ 42-, which doesn't seem that large to me, but I'll do
this if others think that it is large too.

> It's worth spending some extra time looking at this test pattern as I 
> believe we will want to follow it with other arbitrary repository changes.

I agree - let me know if you notice anything you think should be
changed.

> > +static void test_get_commit_tree_in_graph(const char *gitdir,
> > +					  const char *worktree,
> > +					  const struct object_id *commit_oid)
> > +{
> > +	struct repository r;
> > +	struct commit *c;
> > +	struct tree *tree;
> > +
> > +	/*
> > +	 * Create a commit independent of any repository.
> > +	 */
> > +	c = lookup_commit(commit_oid);
> 
> Would this be more accurate to say we are creating a commit object 
> stored in the object cache of the_repository? How would you expect this 
> to work if/when lookup_commit() takes an arbitrary repository? You want 
> to provide &r, right (after initializing)?

Yes, you're right - Stefan too mentioned that this will need to be moved
below lookup_commit(). I'm not sure what the best way is to handle this
- maybe move this, and add a "needswork" stating that we need to pass r
to lookup_commit once it supports taking in a repository argument, as an
aid to the person who performs the merge. I'll do that if a reroll is
needed.

> Also, this will conflict with sb/object-store-lookup, won't it? I'm 
> guessing this is why you didn't touch the "git commit-graph 
> [write|verify]"code paths.

It will conflict because of the change to lookup_commit(), but the only
new code I'm writing is in t/helper/test-repository.c, so hopefully the
merge won't be too tedious. The main reason why I didn't touch the
writing/verifying part is to reduce the size of this patch set, and
because that change is not needed to update parse_commit() and others.

> > +
> > +	repo_init(&r, gitdir, worktree);
> 
> I think you want to move the lookup_commit() to after this.

Yes, that's right.

> > +int cmd__repository(int argc, const char **argv)
> > +{
> > +	if (argc < 2)
> > +		die("must have at least 2 arguments");
> 
> I think this "test-tool repository <verb>" pattern is a good way to get 
> some testing here.

Thanks.