git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: Jeff King <peff@peff.net>
To: "René Scharfe" <l.s.r@web.de>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Git List" <git@vger.kernel.org>, "Taylor Blau" <me@ttaylorr.com>,
	"Christian Couder" <chriscool@tuxfamily.org>
Subject: Re: [PATCH v2 3/3] Revert "pack-objects: lazily set up "struct rev_info", don't leak"
Date: Mon, 28 Nov 2022 20:26:06 -0500	[thread overview]
Message-ID: <Y4VfrsYwWkestQ05@coredump.intra.peff.net> (raw)
In-Reply-To: <0b86ae8b-5523-3857-cdba-12275f727cde@web.de>

On Mon, Nov 28, 2022 at 10:57:02PM +0100, René Scharfe wrote:

> >> diff --git a/revision.c b/revision.c
> >> index 439e34a7c5..6a51ef9418 100644
> >> --- a/revision.c
> >> +++ b/revision.c
> >> @@ -3055,6 +3055,7 @@ void release_revisions(struct rev_info *revs)
> >>  	release_revisions_mailmap(revs->mailmap);
> >>  	free_grep_patterns(&revs->grep_filter);
> >>  	/* TODO (need to handle "no_free"): diff_free(&revs->diffopt) */
> >> +	FREE_AND_NULL(revs->diffopt.parseopts);
> >>  	diff_free(&revs->pruning);
> >>  	reflog_walk_info_release(revs->reflog_info);
> >>  	release_revisions_topo_walk_info(revs->topo_walk_info);
> >
> > At this point I'm unclear on what & why this is needed? I.e. once we
> > narrowly fix the >1 "--filter" options what still fails?
> 
> As I wrote: A call to an initialization function followed by a call to a
> cleanup function and nothing else shouldn't leak.  There are examples of
> repo_init_revisions()+release_revisions() without setup_revisions() or
> diff_setup_done() beyond pack-objects.  I mentioned prune, but there are
> more, e.g. in sequencer.c.

I tend to agree with you; an init+release combo should release all
memory. We _can_ work around it in the caller here, but I think we are
better to correct the root cause.

I do think what Ævar is saying is: once we have fixed the bug, why are
more changes needed? I.e., why would we get rid of the lazy-init. IMHO
the answer is that the lazy-init is a more complex pattern, and requires
more boilerplate code (which can lead to more bugs, as we saw). So once
the bug is fixed, this is purely about cleanup/simplification (if one
ignores the C-standard issues), but I tend to think it is one worth
doing.

(Apologies to Ævar if I'm mis-stating your position).

> > But in general: I don't really think this sort of thing is worth
> > it. Here we're reaching into a member of "revs->diffopt" behind its back
> > rather than calling diff_free(). I think we should just focus on being
> > able to do do that safely.
> 
> Sure, but the FREE_AND_NULL call is simple and safe, while diff_free()
> is complicated and calling it one time too many can hurt.

Again, I'd agree with you here. In the long run, yes, we want
diff_free(). But if that is not ready yet, the FREE_AND_NULL() is a
stepping stone that takes us in the right direction and which we can do
immediately.

> > WIP patches I have in that direction, partially based on your previous
> > "is_dead" suggestion:
> >
> > 	https://github.com/avar/git/commit/e02a15f6206
> > 	https://github.com/avar/git/commit/c718f36566a
> 
> Copy-typed the interesting parts of the first patch like a medieval monk
> because there doesn't seem to be a download option. :-|

This is the actual reason I responded to your message. ;) Try:

  https://github.com/avar/git/commit/e02a15f6206.patch

etc. I don't think there's a "raw patch" link or similar in the
interface, though. You have to just know about it.

-Peff

  reply	other threads:[~2022-11-29  1:29 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-12 10:42 [PATCH 0/3] pack-objects: fix and simplify --filter handling René Scharfe
2022-11-12 10:44 ` [PATCH 1/3] pack-objects: fix handling of multiple --filter options René Scharfe
2022-11-12 11:41   ` Ævar Arnfjörð Bjarmason
2022-11-13 17:31     ` René Scharfe
2022-11-12 16:58   ` Jeff King
2022-11-13  5:01     ` Taylor Blau
2022-11-13 16:44       ` Jeff King
2022-11-13 17:31       ` René Scharfe
2022-11-12 10:44 ` [PATCH 2/3] pack-object: simplify --filter handling René Scharfe
2022-11-12 11:45   ` Ævar Arnfjörð Bjarmason
2022-11-12 17:02   ` Jeff King
2022-11-13 16:49     ` Jeff King
2022-11-13 17:31     ` René Scharfe
2022-11-12 10:46 ` [PATCH 3/3] list-objects-filter: remove OPT_PARSE_LIST_OBJECTS_FILTER_INIT() René Scharfe
2022-11-20 10:03 ` [PATCH v2 0/3] pack-objects: fix and simplify --filter handling René Scharfe
2022-11-20 10:06   ` [PATCH v2 1/3] t5317: stop losing return codes of git ls-files René Scharfe
2022-11-20 10:07   ` [PATCH v2 2/3] t5317: demonstrate failure to handle multiple --filter options René Scharfe
2022-11-20 10:13   ` [PATCH v2 3/3] Revert "pack-objects: lazily set up "struct rev_info", don't leak" René Scharfe
2022-11-28 10:03     ` Junio C Hamano
2022-11-28 11:12       ` Ævar Arnfjörð Bjarmason
2022-11-28 12:00         ` [PATCH] t5314: check exit code of "rev-parse" Ævar Arnfjörð Bjarmason
2022-11-28 13:51           ` René Scharfe
2022-11-28 14:18           ` [PATCH v2] t5314: check exit code of "git" Ævar Arnfjörð Bjarmason
2022-11-28 11:26       ` [PATCH v2 3/3] Revert "pack-objects: lazily set up "struct rev_info", don't leak" René Scharfe
2022-11-28 11:31         ` Ævar Arnfjörð Bjarmason
2022-11-28 12:24           ` Ævar Arnfjörð Bjarmason
2022-11-28 15:16             ` René Scharfe
2022-11-28 15:27               ` Ævar Arnfjörð Bjarmason
2022-11-28 14:29           ` René Scharfe
2022-11-28 14:34             ` Ævar Arnfjörð Bjarmason
2022-11-28 15:56               ` René Scharfe
2022-11-28 17:57                 ` René Scharfe
2022-11-28 18:32                   ` Ævar Arnfjörð Bjarmason
2022-11-28 21:57                     ` René Scharfe
2022-11-29  1:26                       ` Jeff King [this message]
2022-11-29  1:46                         ` Junio C Hamano
2022-11-29 10:25                         ` Ævar Arnfjörð Bjarmason
2022-11-29  7:12                       ` Ævar Arnfjörð Bjarmason
2022-11-29 19:18                         ` René Scharfe
2022-11-28 17:57                 ` Ævar Arnfjörð Bjarmason
2022-11-22 19:02   ` [PATCH v2 0/3] pack-objects: fix and simplify --filter handling Jeff King
2022-11-29 12:19 ` [PATCH v3 0/5] " René Scharfe
2022-11-29 12:21   ` [PATCH v3 1/5] t5317: stop losing return codes of git ls-files René Scharfe
2022-11-29 12:22   ` [PATCH v3 2/5] t5317: demonstrate failure to handle multiple --filter options René Scharfe
2022-11-29 12:23   ` [PATCH v3 3/5] pack-objects: fix handling of " René Scharfe
2022-11-30  1:09     ` Junio C Hamano
2022-11-30  7:11       ` René Scharfe
2022-11-29 12:25   ` [PATCH v3 4/5] pack-objects: simplify --filter handling René Scharfe
2022-11-29 13:27     ` Ævar Arnfjörð Bjarmason
2022-11-30 11:23       ` René Scharfe
2022-11-29 12:26   ` [PATCH v3 5/5] list-objects-filter: remove OPT_PARSE_LIST_OBJECTS_FILTER_INIT() René Scharfe
2022-11-30  1:20     ` Junio C Hamano

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=Y4VfrsYwWkestQ05@coredump.intra.peff.net \
    --to=peff@peff.net \
    --cc=avarab@gmail.com \
    --cc=chriscool@tuxfamily.org \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=l.s.r@web.de \
    --cc=me@ttaylorr.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).