From: Junio C Hamano <gitster@pobox.com>
To: Stephan Beyer <s-beyer@gmx.net>
Cc: git@vger.kernel.org, Christian Couder <christian.couder@gmail.com>
Subject: Re: [PATCH v2 10/21] bisect: get rid of recursion in count_distance()
Date: Fri, 15 Apr 2016 14:31:10 -0700 [thread overview]
Message-ID: <xmqq4mb2a7a9.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <1460294354-7031-11-git-send-email-s-beyer@gmx.net> (Stephan Beyer's message of "Sun, 10 Apr 2016 15:19:03 +0200")
Stephan Beyer <s-beyer@gmx.net> writes:
> Large repositories with a huge amount of merge commits in the
> bisection process could lead to stack overflows in git bisect.
> In order to prevent this, this commit uses an *iterative* version
> for counting the number of ancestors of a commit.
Yay!
> -/*
> - * This is a truly stupid algorithm, but it's only
> - * used for bisection, and we just don't care enough.
> - *
> - * We care just barely enough to avoid recursing for
> - * non-merge entries.
> - */
> static int count_distance(struct commit_list *entry)
> {
> int nr = 0;
> + struct commit_list *todo = NULL;
> + commit_list_append(entry->item, &todo);
>
> - while (entry) {
> - struct commit *commit = entry->item;
> - struct commit_list *p;
> + while (todo) {
> + struct commit *commit = pop_commit(&todo);
>
> - if (commit->object.flags & (UNINTERESTING | COUNTED))
> - break;
> - if (!(commit->object.flags & TREESAME))
> - nr++;
> - commit->object.flags |= COUNTED;
> - p = commit->parents;
> - entry = p;
> - if (p) {
> - p = p->next;
> - while (p) {
> - nr += count_distance(p);
> - p = p->next;
> + if (!(commit->object.flags & (UNINTERESTING | COUNTED))) {
> + struct commit_list *p;
> + if (!(commit->object.flags & TREESAME))
> + nr++;
> + commit->object.flags |= COUNTED;
> +
> + for (p = commit->parents; p; p = p->next) {
> + commit_list_insert(p->item, &todo);
> }
> }
> }
> @@ -287,7 +277,7 @@ static struct commit_list *do_find_bisection(struct commit_list *list,
> * can reach. So we do not have to run the expensive
> * count_distance() for single strand of pearls.
> *
> - * However, if you have more than one parents, you cannot
> + * However, if you have more than one parent, you cannot
Thanks. This grammo is mine, back in 1c4fea3a (git-rev-list
--bisect: optimization, 2007-03-21)
> @@ -296,17 +286,16 @@ static struct commit_list *do_find_bisection(struct commit_list *list,
> * way, and then fill the blanks using cheaper algorithm.
> */
> for (p = list; p; p = p->next) {
> - if (p->item->object.flags & UNINTERESTING)
> - continue;
> - if (weight(p) != -2)
> - continue;
> - weight_set(p, count_distance(p));
> - clear_distance(list);
> + if (!(p->item->object.flags & UNINTERESTING)
> + && (weight(p) == -2)) {
> + weight_set(p, count_distance(p));
> + clear_distance(list);
>
> - /* Does it happen to be at exactly half-way? */
> - if (!find_all && halfway(p, nr))
> - return p;
> - counted++;
> + /* Does it happen to be at exactly half-way? */
> + if (!find_all && halfway(p, nr))
> + return p;
> + counted++;
> + }
> }
I can buy collapsing two if() statements into one, but I'd prefer to
see us keep the structure:
loop () {
if (... || ...)
continue;
quite a
many
operations
here
}
>
> show_list("bisection 2 count_distance", counted, nr, list);
next prev parent reply other threads:[~2016-04-15 21:31 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-10 13:18 [PATCH v2 00/21] git bisect improvements Stephan Beyer
2016-04-10 13:18 ` [PATCH v2 01/21] bisect: write about `bisect next` in documentation Stephan Beyer
2016-04-10 13:18 ` [PATCH v2 02/21] bisect: allow 'bisect run' if no good commit is known Stephan Beyer
2016-04-10 13:18 ` [PATCH v2 03/21] t/test-lib-functions.sh: generalize test_cmp_rev Stephan Beyer
2016-04-11 0:07 ` Eric Sunshine
2016-04-15 20:00 ` Junio C Hamano
2016-04-24 19:51 ` Stephan Beyer
2016-04-25 18:08 ` Junio C Hamano
2016-04-10 13:18 ` [PATCH v2 04/21] t: use test_cmp_rev() where appropriate Stephan Beyer
2016-04-11 0:07 ` Eric Sunshine
2016-04-15 20:48 ` Junio C Hamano
2016-04-10 13:18 ` [PATCH v2 05/21] t6030: generalize test to not rely on current implementation Stephan Beyer
2016-04-10 13:47 ` Torsten Bögershausen
2016-04-10 19:16 ` Junio C Hamano
2016-04-10 19:37 ` Stephan Beyer
2016-04-11 0:23 ` Eric Sunshine
2016-04-15 21:07 ` Junio C Hamano
2016-04-10 13:18 ` [PATCH v2 06/21] bisect: add test for the bisect algorithm Stephan Beyer
2016-04-15 21:13 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 07/21] bisect: plug the biggest memory leak Stephan Beyer
2016-04-15 21:18 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 08/21] bisect: make bisect compile if DEBUG_BISECT is set Stephan Beyer
2016-04-15 21:22 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 09/21] bisect: make algorithm behavior independent of DEBUG_BISECT Stephan Beyer
2016-04-15 21:25 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 10/21] bisect: get rid of recursion in count_distance() Stephan Beyer
2016-04-15 21:31 ` Junio C Hamano [this message]
2016-04-10 13:19 ` [PATCH v2 11/21] bisect: use struct node_data array instead of int array Stephan Beyer
2016-04-12 23:02 ` Christian Couder
2016-04-15 21:47 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 12/21] bisect: replace clear_distance() by unique markers Stephan Beyer
2016-04-12 23:20 ` Christian Couder
2016-04-15 22:07 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 13/21] bisect: use commit instead of commit list as arguments when appropriate Stephan Beyer
2016-04-15 22:08 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 14/21] bisect: extract get_distance() function from code duplication Stephan Beyer
2016-04-15 22:08 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 15/21] bisect: introduce distance_direction() Stephan Beyer
2016-04-15 22:10 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 16/21] bisect: make total number of commits global Stephan Beyer
2016-04-13 13:23 ` Christian Couder
2016-04-15 22:11 ` Junio C Hamano
2016-04-16 0:44 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 17/21] bisect: rename count_distance() to compute_weight() Stephan Beyer
2016-04-13 13:32 ` Christian Couder
2016-04-15 22:12 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 18/21] bisect: prepare for different algorithms based on find_all Stephan Beyer
2016-04-15 22:36 ` Junio C Hamano
2016-04-10 13:19 ` [PATCH v2 19/21] bisect: use a bottom-up traversal to find relevant weights Stephan Beyer
2016-04-13 14:11 ` Christian Couder
2016-04-15 22:47 ` Junio C Hamano
2016-04-15 22:49 ` Junio C Hamano
2016-04-26 18:27 ` Junio C Hamano
2016-04-10 13:24 ` [PATCH v2 20/21] bisect: compute best bisection in compute_relevant_weights() Stephan Beyer
2016-04-10 13:24 ` [PATCH v2 21/21] bisect: get back halfway shortcut Stephan Beyer
2016-04-15 22:53 ` 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=xmqq4mb2a7a9.fsf@gitster.mtv.corp.google.com \
--to=gitster@pobox.com \
--cc=christian.couder@gmail.com \
--cc=git@vger.kernel.org \
--cc=s-beyer@gmx.net \
/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).