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From: Elijah Newren <newren@gmail.com>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Git Mailing List <git@vger.kernel.org>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 04/19] merge-recursive: exit early if index != head
Date: Thu, 25 Jul 2019 13:12:00 -0700	[thread overview]
Message-ID: <CABPp-BEfqsCn11kHEAdHX9+fFv6iiSLV9TTL5XaZ_aDccNft6w@mail.gmail.com> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.1907252142470.21907@tvgsbejvaqbjf.bet>

On Thu, Jul 25, 2019 at 12:51 PM Johannes Schindelin
<Johannes.Schindelin@gmx.de> wrote:
>
> Hi Elijah,
>
> On Thu, 25 Jul 2019, Elijah Newren wrote:
>
> > We had a rule to enforce that the index matches head, but it was found
> > at the beginning of merge_trees() and would only trigger when
> > opt->call_depth was 0.  Since merge_recursive() doesn't call
> > merge_trees() until after returning from recursing, this meant that the
> > check wasn't triggered by merge_recursive() until it had first finished
> > all the intermediate merges to create virtual merge bases.  That is a
> > potentially huge amount of computation (and writing of intermediate
> > merge results into the .git/objects directory) before it errors out and
> > says, in effect, "Sorry, I can't do any merging because you have some
> > local changes that would be overwritten."
> >
> > Further, not enforcing this requirement earlier allowed other bugs (such
> > as an unintentional unconditional dropping and reloading of the index in
> > merge_recursive() even when no recursion was necessary), to mask bugs in
> > other callers (which were fixed in the commit prior to this one).
> >
> > Make sure we do the index == head check at the beginning of the merge,
> > and error out immediately if it fails.
>
> Very clear commit message.
>
> > diff --git a/merge-recursive.c b/merge-recursive.c
> > index 37bb94fb4d..b762ecd7bd 100644
> > --- a/merge-recursive.c
> > +++ b/merge-recursive.c
> > @@ -3381,21 +3381,14 @@ static int process_entry(struct merge_options *opt,
> >       return clean_merge;
> >  }
> >
> > -int merge_trees(struct merge_options *opt,
> > -             struct tree *head,
> > -             struct tree *merge,
> > -             struct tree *common,
> > -             struct tree **result)
> > +static int merge_trees_internal(struct merge_options *opt,
>
> In other, similar cases, we seem to use the suffix `_1`. Not sure
> whether you want to change that here.

Hmm, we do seem to use `_1` about 2.5 times as frequently as
`_internal`, but both do seem to be in use to me (e.g.
init_tree_desc_internal, convert_to_working_tree_internal,
repo_parse_commit_internal).  `_1` does have the advantage of being
shorter, which makes lines fit in 80 columns better, but `_internal`
seems like a clearer description to me.

So...I'm not sure what's best here.  I don't have a strong opinion,
but I'm inclined towards laziness and leaving it alone unless someone
else has strong opinions.

> > +{
> > +     struct strbuf sb = STRBUF_INIT;
> > +
> > +     assert(opt->branch1 && opt->branch2);
> > +
> > +     if (repo_index_has_changes(opt->repo, head, &sb)) {
> > +             err(opt, _("Your local changes to the following files would be overwritten by merge:\n  %s"),
> > +                 sb.buf);
>
> I know that you did not introduce this leak, but maybe we could slip an
> `strbuf_release(&sb);` in at this point?

Ooh, good point.  I'll fix that up for round 2.

> > +             return -1;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static void merge_finalize(struct merge_options *opt)
> > +{
> > +     /* Common code for wrapping up merges will be added here later */
> > +}
>
> I was about to comment that this complicates this here diff and that we
> should do this when we need it, but I just peeked into the next patch,
> and it uses it, so I leave this here paragraph only to show that I
> actually reviewed this part, too.
>
> And of course, if we have a `merge_finalize()`, then a `merge_start()`
> does not sound all that bad, either.
>
> The rest looks good to me.

Thanks!

  reply	other threads:[~2019-07-25 20:12 UTC|newest]

Thread overview: 157+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-25 17:45 [PATCH 00/19] Cleanup merge API Elijah Newren
2019-07-25 17:45 ` [PATCH 01/19] merge-recursive: fix minor memory leak in error condition Elijah Newren
2019-07-25 17:45 ` [PATCH 02/19] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-07-25 17:45 ` [PATCH 03/19] Ensure index matches head before invoking merge machinery, round N Elijah Newren
2019-07-25 19:41   ` Johannes Schindelin
2019-07-25 19:58     ` Elijah Newren
2019-07-26 11:23       ` Johannes Schindelin
2019-07-25 17:45 ` [PATCH 04/19] merge-recursive: exit early if index != head Elijah Newren
2019-07-25 19:51   ` Johannes Schindelin
2019-07-25 20:12     ` Elijah Newren [this message]
2019-07-25 17:45 ` [PATCH 05/19] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-07-25 17:45 ` [PATCH 06/19] Change call signature of write_tree_from_memory() Elijah Newren
2019-07-25 19:55   ` Johannes Schindelin
2019-07-26  4:58     ` Elijah Newren
2019-07-25 17:45 ` [PATCH 07/19] Move write_tree_from_memory() from merge-recursive to cache-tree Elijah Newren
2019-07-25 17:46 ` [PATCH 08/19] merge-recursive: fix some overly long lines Elijah Newren
2019-07-25 17:46 ` [PATCH 09/19] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-07-25 17:46 ` [PATCH 10/19] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-07-25 20:02   ` Johannes Schindelin
2019-07-25 17:46 ` [PATCH 11/19] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-07-25 17:46 ` [PATCH 12/19] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-07-25 17:46 ` [PATCH 13/19] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-07-25 17:46 ` [PATCH 14/19] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-07-25 17:46 ` [PATCH 15/19] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-07-25 20:12   ` Johannes Schindelin
2019-07-25 20:27     ` Elijah Newren
2019-07-26 11:25       ` Johannes Schindelin
2019-07-26 15:30         ` Elijah Newren
2019-07-25 17:46 ` [PATCH 16/19] merge-recursive: alphabetize include list Elijah Newren
2019-07-25 17:46 ` [PATCH 17/19] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-07-25 17:46 ` [PATCH 18/19] merge-recursive: be consistent with assert Elijah Newren
2019-07-25 17:46 ` [PATCH 19/19] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-07-25 20:28   ` Johannes Schindelin
2019-07-25 18:12 ` [PATCH 00/19] Cleanup merge API Junio C Hamano
2019-07-25 19:06   ` Elijah Newren
2019-07-25 22:50     ` Junio C Hamano
2019-07-26 14:07       ` Johannes Schindelin
2019-07-25 19:15 ` Johannes Schindelin
2019-07-26 15:15   ` Elijah Newren
2019-07-26 15:52 ` [PATCH v2 00/20] " Elijah Newren
2019-07-26 15:52   ` [PATCH v2 01/20] merge-recursive: fix minor memory leak in error condition Elijah Newren
2019-07-26 18:31     ` Junio C Hamano
2019-07-26 23:19       ` Elijah Newren
2019-07-29 14:13       ` Derrick Stolee
2019-07-26 15:52   ` [PATCH v2 02/20] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-07-26 18:42     ` Junio C Hamano
2019-07-26 15:52   ` [PATCH v2 03/20] Ensure index matches head before invoking merge machinery, round N Elijah Newren
2019-07-26 19:14     ` Junio C Hamano
2019-07-26 23:22       ` Elijah Newren
2019-07-26 15:52   ` [PATCH v2 04/20] merge-recursive: exit early if index != head Elijah Newren
2019-07-26 19:32     ` Junio C Hamano
2019-07-26 23:26       ` Elijah Newren
2019-07-29 15:56         ` Junio C Hamano
2019-07-26 15:52   ` [PATCH v2 05/20] merge-recursive: remove useless parameter in merge_trees() Elijah Newren
2019-07-26 19:37     ` Junio C Hamano
2019-07-26 15:52   ` [PATCH v2 06/20] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-07-26 19:57     ` Junio C Hamano
2019-07-26 23:28       ` Elijah Newren
2019-07-26 15:52   ` [PATCH v2 07/20] Use write_index_as_tree() in lieu of write_tree_from_memory() Elijah Newren
2019-07-26 20:11     ` Junio C Hamano
2019-07-26 23:39       ` Elijah Newren
2019-07-29  4:46         ` Junio C Hamano
2019-07-26 15:52   ` [PATCH v2 08/20] merge-recursive: fix some overly long lines Elijah Newren
2019-07-26 15:52   ` [PATCH v2 09/20] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-07-26 15:52   ` [PATCH v2 10/20] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-07-26 15:52   ` [PATCH v2 11/20] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-07-26 15:52   ` [PATCH v2 12/20] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-07-26 15:52   ` [PATCH v2 13/20] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-07-26 15:52   ` [PATCH v2 14/20] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-07-26 15:52   ` [PATCH v2 15/20] merge-recursive: avoid losing output and leaking memory holding that output Elijah Newren
2019-07-26 15:52   ` [PATCH v2 16/20] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-07-26 15:52   ` [PATCH v2 17/20] merge-recursive: alphabetize include list Elijah Newren
2019-07-26 15:52   ` [PATCH v2 18/20] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-07-26 15:52   ` [PATCH v2 19/20] merge-recursive: be consistent with assert Elijah Newren
2019-07-26 15:52   ` [PATCH v2 20/20] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-08-15 21:40   ` [PATCH v3 00/24] Clean up merge API Elijah Newren
2019-08-15 21:40     ` [PATCH v3 01/24] merge-recursive: be consistent with assert Elijah Newren
2019-08-15 21:40     ` [PATCH v3 02/24] checkout: provide better conflict hunk description with detached HEAD Elijah Newren
2019-08-15 21:40     ` [PATCH v3 03/24] merge-recursive: enforce opt->ancestor != NULL when calling merge_trees() Elijah Newren
2019-08-16 21:05       ` Junio C Hamano
2019-08-15 21:40     ` [PATCH v3 04/24] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-08-16 21:33       ` Junio C Hamano
2019-08-16 22:39         ` Elijah Newren
2019-08-15 21:40     ` [PATCH v3 05/24] merge-recursive: introduce an enum for detect_directory_renames values Elijah Newren
2019-08-15 21:40     ` [PATCH v3 06/24] merge-recursive: future-proof update_file_flags() against memory leaks Elijah Newren
2019-08-15 21:40     ` [PATCH v3 07/24] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-08-15 21:40     ` [PATCH v3 08/24] Ensure index matches head before invoking merge machinery, round N Elijah Newren
2019-08-15 21:40     ` [PATCH v3 09/24] merge-recursive: exit early if index != head Elijah Newren
2019-08-15 21:40     ` [PATCH v3 10/24] merge-recursive: remove useless parameter in merge_trees() Elijah Newren
2019-08-15 21:40     ` [PATCH v3 11/24] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-08-15 21:40     ` [PATCH v3 12/24] cache-tree: share code between functions writing an index as a tree Elijah Newren
2019-08-16 22:01       ` Junio C Hamano
2019-08-16 22:39         ` Elijah Newren
2019-08-15 21:40     ` [PATCH v3 13/24] merge-recursive: fix some overly long lines Elijah Newren
2019-08-15 21:40     ` [PATCH v3 14/24] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-08-15 21:40     ` [PATCH v3 15/24] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-08-15 21:40     ` [PATCH v3 16/24] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-08-15 21:40     ` [PATCH v3 17/24] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-08-15 21:40     ` [PATCH v3 18/24] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-08-16 22:14       ` Junio C Hamano
2019-08-16 22:59         ` Elijah Newren
2019-08-16 23:24           ` Junio C Hamano
2019-08-15 21:40     ` [PATCH v3 19/24] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-08-15 21:40     ` [PATCH v3 20/24] merge-recursive: avoid losing output and leaking memory holding that output Elijah Newren
2019-08-15 21:40     ` [PATCH v3 21/24] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-08-16 21:19       ` SZEDER Gábor
2019-08-16 23:00         ` Elijah Newren
2019-08-16 22:17       ` Junio C Hamano
2019-08-15 21:40     ` [PATCH v3 22/24] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-08-15 21:40     ` [PATCH v3 23/24] merge-recursive: add sanity checks for relevant merge_options Elijah Newren
2019-08-16 19:52       ` Junio C Hamano
2019-08-16 22:08         ` Elijah Newren
2019-08-16 23:15           ` Junio C Hamano
2019-08-16 19:59       ` Junio C Hamano
2019-08-16 22:09         ` Elijah Newren
2019-08-15 21:40     ` [PATCH v3 24/24] merge-recursive: alphabetize include list Elijah Newren
2019-08-17 18:41     ` [PATCH v4 00/24] Clean up merge API Elijah Newren
2019-08-17 18:41       ` [PATCH v4 01/24] merge-recursive: be consistent with assert Elijah Newren
2019-08-17 18:41       ` [PATCH v4 02/24] checkout: provide better conflict hunk description with detached HEAD Elijah Newren
2019-08-17 18:41       ` [PATCH v4 03/24] merge-recursive: enforce opt->ancestor != NULL when calling merge_trees() Elijah Newren
2019-08-17 18:41       ` [PATCH v4 04/24] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-09-30 21:14         ` Jeff King
2019-09-30 21:19           ` Jeff King
2019-09-30 22:54           ` [PATCH] merge-recursive: fix the diff3 common ancestor label for virtual commits Elijah Newren
2019-10-01  6:56             ` Elijah Newren
2019-10-01  6:58             ` [PATCH v2] " Elijah Newren
2019-10-01 14:49               ` Jeff King
2019-10-01 18:17                 ` [PATCH v3] " Elijah Newren
2019-10-07  2:51                   ` Junio C Hamano
2019-10-07 15:52                     ` [PATCH] merge-recursive: fix the fix to the diff3 common ancestor label Elijah Newren
2019-10-08  2:32                       ` Junio C Hamano
2019-10-08  2:36                       ` Junio C Hamano
2019-10-08 16:16                         ` Elijah Newren
2019-08-17 18:41       ` [PATCH v4 05/24] merge-recursive: introduce an enum for detect_directory_renames values Elijah Newren
2019-08-17 18:41       ` [PATCH v4 06/24] merge-recursive: future-proof update_file_flags() against memory leaks Elijah Newren
2019-08-17 18:41       ` [PATCH v4 07/24] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-08-17 18:41       ` [PATCH v4 08/24] Ensure index matches head before invoking merge machinery, round N Elijah Newren
2019-09-02 23:01         ` Johannes Schindelin
2019-09-03 13:34           ` Johannes Schindelin
2019-09-03 18:17             ` Elijah Newren
2019-08-17 18:41       ` [PATCH v4 09/24] merge-recursive: exit early if index != head Elijah Newren
2019-08-17 18:41       ` [PATCH v4 10/24] merge-recursive: remove useless parameter in merge_trees() Elijah Newren
2019-08-17 18:41       ` [PATCH v4 11/24] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-08-17 18:41       ` [PATCH v4 12/24] cache-tree: share code between functions writing an index as a tree Elijah Newren
2019-08-17 18:41       ` [PATCH v4 13/24] merge-recursive: fix some overly long lines Elijah Newren
2019-08-17 18:41       ` [PATCH v4 14/24] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-08-17 18:41       ` [PATCH v4 15/24] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-08-17 18:41       ` [PATCH v4 16/24] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-08-17 18:41       ` [PATCH v4 17/24] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-08-17 18:41       ` [PATCH v4 18/24] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-08-17 18:41       ` [PATCH v4 19/24] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-08-17 18:41       ` [PATCH v4 20/24] merge-recursive: avoid losing output and leaking memory holding that output Elijah Newren
2019-08-17 18:41       ` [PATCH v4 21/24] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-08-19 17:17         ` Junio C Hamano
2019-08-17 18:41       ` [PATCH v4 22/24] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-08-17 18:41       ` [PATCH v4 23/24] merge-recursive: add sanity checks for relevant merge_options Elijah Newren
2019-08-17 18:41       ` [PATCH v4 24/24] merge-recursive: alphabetize include list Elijah Newren

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