From: Taylor Blau <me@ttaylorr.com>
To: "Martin Ågren" <martin.agren@gmail.com>
Cc: Taylor Blau <me@ttaylorr.com>,
Git Mailing List <git@vger.kernel.org>, Jeff King <peff@peff.net>,
Derrick Stolee <dstolee@microsoft.com>,
Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 2/6] commit-graph.h: store object directory in 'struct commit_graph'
Date: Sun, 2 Feb 2020 19:58:19 -0800 [thread overview]
Message-ID: <20200203035819.GA23625@syl.local> (raw)
In-Reply-To: <CAN0heSrrrWjBKnzjMfzEkTMVTge2AfVdwsp6D5Mx==5S8-ZLJQ@mail.gmail.com>
Hi Martin,
Thanks for your review! Your comments were all quite helpful, and I
applied all of your suggested changes.
On Fri, Jan 31, 2020 at 07:52:02AM +0100, Martin Ågren wrote:
> On Fri, 31 Jan 2020 at 00:03, Taylor Blau <me@ttaylorr.com> wrote:
> > Instead of getting rid of the 'struct object_directory *', store that
> > insead of a 'char *odb' in 'struct commit_graph'. Once the 'struct
>
> s/insead/instead/
Typo. Thanks for noticing. I fixed this in my local copy of this branch.
> > if (open_ok)
> > graph = load_commit_graph_one_fd_st(fd, &st);
> > - else
> > - graph = read_commit_graph_one(the_repository, opts.obj_dir);
> > + else {
> > + struct object_directory *odb;
> > + if ((odb = find_odb(the_repository, opts.obj_dir)))
> > + graph = read_commit_graph_one(the_repository, odb);
> > + }
>
> I'm a tiny bit allergic to this assignment-within-if. It's wrapped by
> another pair of parentheses, which both compilers and humans know to
> interpret as "trust me, this is not a mistake", but I still find this
> easier to read:
>
> odb = find_odb(...);
> if (odb)
> ....
To be honest, I'm not such a fan of this style myself, but it seemed odd
to me to write:
struct object_directory *odb;
odb = ...;
if (odb) {
}
when we were really only trying to call 'find_odb()' and do something
with its result, but only if it was non-NULL. I counted 152 of these
assign-if's laying around with:
$ git grep 'if ((.* =[^=]' | wc -l
but it seems like they are in poor style (as evidenced by your and
Junio's response later in the thread). So, I removed this and instead
promoted 'odb' to a local variable at the function level, since we
do that promotion anyway in a couple of patches later. This reduces the
churn, and avoids either an assign-if, or a define/assign/check.
> > --- a/builtin/commit.c
> > +++ b/builtin/commit.c
>
> > +#include "object-store.h"
No; this is a stray left over from some development on this branch. I'll
remove it.
> This is the only change in this file, which looks a bit odd. I haven't
> actually applied your patches, to be honest, but is this inclusion
> really needed?
>
> > --- a/commit-graph.c
> > +++ b/commit-graph.c
>
> > +struct object_directory *find_odb(struct repository *r, const char *obj_dir)
>
> This doesn't look commit-graph related -- could/should it go somewhere
> else?
I'll respond in more complete detail further down in the thread, but the
short answer is "yes, this should go in builtin/commit-graph.c".
> > +{
> > + struct object_directory *odb;
> > + char *obj_dir_real = real_pathdup(obj_dir, 1);
> > + int cmp = -1;
> > +
> > + prepare_alt_odb(r);
> > + for (odb = r->objects->odb; odb; odb = odb->next) {
> > + cmp = strcmp(obj_dir_real, real_path(odb->path));
> > + if (!cmp)
> > + break;
> > + }
>
> At this point, either odb is NULL or cmp is zero. Those are the only two
> ways out of the loop.
>
> > + free(obj_dir_real);
> > +
> > + if (cmp)
> > + odb = NULL;
>
> Meaning that this doesn't do much? If the most recent comparison failed,
> it's because we didn't find anything, so odb will be NULL.
>
> > + return odb;
> > +}
>
> I think you could drop `cmp` and that final check, and write the loop
> body as "if (!strcmp(...)) break". You could also have an empty loop
> body, but I wouldn't go there -- I'd find that less readable. (Maybe
> that's just me.)
Thanks, I changed this to remove the 'cmp' check outside of the loop,
which I agree is unnecessary.
> Martin
Thanks,
Taylor
next prev parent reply other threads:[~2020-02-03 3:58 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-30 23:00 [PATCH 0/6] commit-graph: use 'struct object_directory *' everywhere Taylor Blau
2020-01-30 23:00 ` [PATCH 1/6] t5318: don't pass non-object directory to '--object-dir' Taylor Blau
2020-01-30 23:00 ` [PATCH 5/6] commit-graph.c: remove path normalization, comparison Taylor Blau
2020-01-30 23:00 ` [PATCH 6/6] commit-graph.h: use odb in 'load_commit_graph_one_fd_st' Taylor Blau
2020-01-30 23:00 ` [PATCH 2/6] commit-graph.h: store object directory in 'struct commit_graph' Taylor Blau
2020-01-31 6:52 ` Martin Ågren
2020-01-31 10:20 ` Jeff King
2020-01-31 19:19 ` Martin Ågren
2020-02-03 4:36 ` Taylor Blau
2020-02-03 8:36 ` Jeff King
2020-01-31 20:49 ` Junio C Hamano
2020-02-03 3:58 ` Taylor Blau [this message]
2020-01-30 23:00 ` [PATCH 4/6] commit-graph.h: store an odb in 'struct write_commit_graph_context' Taylor Blau
2020-01-30 23:00 ` [PATCH 3/6] builtin/commit-graph.c: die() with unknown '--object-dir' Taylor Blau
2020-01-31 10:30 ` [PATCH 0/6] commit-graph: use 'struct object_directory *' everywhere Jeff King
2020-01-31 13:22 ` Derrick Stolee
2020-02-03 4:38 ` Taylor Blau
2020-02-03 21:17 ` [PATCH v2 0/5] " Taylor Blau
2020-02-03 21:17 ` [PATCH v2 1/5] t5318: don't pass non-object directory to '--object-dir' Taylor Blau
2020-02-03 21:17 ` [PATCH v2 2/5] commit-graph.h: store an odb in 'struct write_commit_graph_context' Taylor Blau
2020-02-04 5:51 ` Taylor Blau
2020-02-04 19:54 ` Junio C Hamano
2020-02-04 21:28 ` Taylor Blau
2020-02-04 21:44 ` Junio C Hamano
2020-02-03 21:18 ` [PATCH v2 3/5] commit-graph.h: store object directory in 'struct commit_graph' Taylor Blau
2020-02-03 21:18 ` [PATCH v2 4/5] commit-graph.c: remove path normalization, comparison Taylor Blau
2020-02-03 21:18 ` [PATCH v2 5/5] commit-graph.h: use odb in 'load_commit_graph_one_fd_st' Taylor Blau
2020-02-05 12:30 ` [PATCH v2 0/5] commit-graph: use 'struct object_directory *' everywhere Jeff King
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