Re: [PATCH 8/8] commit-graph: drop COMMIT_GRAPH_WRITE_CHECK_OIDS flag

[Taylor Blau <me@ttaylorr.com>]

On Tue, May 05, 2020 at 08:10:40AM -0400, Derrick Stolee wrote:
> On 5/4/2020 9:14 PM, Taylor Blau wrote:
> > Since 7c5c9b9c57 (commit-graph: error out on invalid commit oids in
> > 'write --stdin-commits', 2019-08-05), the commit-graph builtin dies on
> > receiving non-commit OIDs as input to '--stdin-commits'.
> >
> > This behavior can be cumbersome to work around in, say, the case of
> > piping 'git for-each-ref' to 'git commit-graph write --stdin-commits' if
> > the caller does not want to cull out non-commits themselves. In this
> > situation, it would be ideal if 'git commit-graph write' wrote the graph
> > containing the inputs that did pertain to commits, and silently ignored
> > the remainder of the input.
> >
> > Some options have been proposed to the effect of '--[no-]check-oids'
> > which would allow callers to have the commit-graph builtin do just that.
> > After some discussion, it is difficult to imagine a caller who wouldn't
> > want to pass '--no-check-oids', suggesting that we should get rid of the
> > behavior of complaining about non-commit inputs altogether.
> >
> > If callers do wish to retain this behavior, they can easily work around
> > this change by doing the following:
> >
> >     git for-each-ref --format='%(objectname) %(objecttype) %(*objecttype)' |
> >     awk '/commit/ { print $1 }' |
> >     git commit-graph write --stdin-commits
>
> I appreciate that you included the workaround here for posterity. That
> allows anyone complaining to bisect to these instructions.

Well, now that I linked provided a link to [2] in the cover letter,
you'll see that it was Peff's suggestion ;).

But, I wrote something similar to this in one of GitHub's
post-processing jobs before we had this series, so I think I can take
some of the credit!

> > To make it so that valid OIDs that refer to non-existent objects are
> > indeed an error after loosening the error handling, perform an extra
> > lookup to make sure that object indeed exists before sending it to the
> > commit-graph internals.
> >
> > Signed-off-by: Taylor Blau <me@ttaylorr.com>
> > ---
> >  Documentation/git-commit-graph.txt |  6 ++++--
> >  builtin/commit-graph.c             | 10 +++++-----
> >  commit-graph.c                     |  2 --
> >  commit-graph.h                     | 10 ++++------
> >  t/t5318-commit-graph.sh            | 15 +++++++++++----
> >  5 files changed, 24 insertions(+), 19 deletions(-)
> >
> > diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
> > index 53a650225a..fcac7d12e1 100644
> > --- a/Documentation/git-commit-graph.txt
> > +++ b/Documentation/git-commit-graph.txt
> > @@ -47,8 +47,10 @@ with `--stdin-commits` or `--reachable`.)
> >  +
> >  With the `--stdin-commits` option, generate the new commit graph by
> >  walking commits starting at the commits specified in stdin as a list
> > -of OIDs in hex, one OID per line. (Cannot be combined with
> > -`--stdin-packs` or `--reachable`.)
> > +of OIDs in hex, one OID per line. OIDs that resolve to non-commits
> > +(either directly, or by peeling tags) are silently ignored. OIDs that
> > +are malformed, or do not exist generate an error. (Cannot be combined
> > +with `--stdin-packs` or `--reachable`.)
> >  +
> >  With the `--reachable` option, generate the new commit graph by walking
> >  commits starting at all refs. (Cannot be combined with `--stdin-commits`
> > diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
> > index 9eec68572f..3637d079fb 100644
> > --- a/builtin/commit-graph.c
> > +++ b/builtin/commit-graph.c
> > @@ -153,13 +153,14 @@ static int read_one_commit(struct oidset *commits, struct progress *progress,
> >
> >  	display_progress(progress, oidset_size(commits) + 1);
> >
> > +	if (oid_object_info(the_repository, &oid, NULL) < 0) {
> > +		error(_("object %s does not exist"), hash);
> > +		return 1;
> > +	}
> > +
>
> If we get a non-existent object, then this will cause us to fail
> the command, right?
>
> > diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
> > index 89020d3d44..74f93f0a17 100755
> > --- a/t/t5318-commit-graph.sh
> > +++ b/t/t5318-commit-graph.sh
> > @@ -84,11 +84,18 @@ graph_read_expect() {
> >
> >  test_expect_success 'exit with correct error on bad input to --stdin-commits' '
> >  	cd "$TRASH_DIRECTORY/full" &&
> > -	echo HEAD | test_expect_code 1 git commit-graph write --stdin-commits 2>stderr &&
> > +	# invalid, non-hex OID
> > +	echo HEAD >in &&
> > +	test_expect_code 1 git commit-graph write --stdin-commits <in 2>stderr &&
> >  	test_i18ngrep "unexpected non-hex object ID: HEAD" stderr &&
> > -	# valid tree OID, but not a commit OID
> > -	git rev-parse HEAD^{tree} | test_expect_code 1 git commit-graph write --stdin-commits 2>stderr &&
> > -	test_i18ngrep "invalid commit object id" stderr
> > +	# non-existent OID
> > +	echo $ZERO_OID >in &&
> > +	test_expect_code 1 git commit-graph write --stdin-commits <in 2>stderr &&
> > +	test_i18ngrep "does not exist" stderr &&
>
> And here you verify that it fails at that point. Excellent!
>
> > +	# valid commit and tree OID
> > +	git rev-parse HEAD HEAD^{tree} >in &&
> > +	git commit-graph write --stdin-commits <in &&
> > +	graph_read_expect 3
> >  '
>
> This is an excellent series! Thanks.
>
> Reviewed-by: Derrick Stolee <dstolee@microsoft.com>

Thanks for your review. I applied your suggested changes locally (which
came down to tweaking the progress meter's messages in the 2nd and 5th
patches), but I'll sit on them for a day or so to make sure that nobody
else has any thoughts before sending a v2.

Thanks,
Taylor