git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / Atom feed
From: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>
Subject: [PATCH 0/6] Use generation numbers for --topo-order
Date: Mon, 27 Aug 2018 13:41:21 -0700 (PDT)
Message-ID: <pull.25.git.gitgitgadget@gmail.com> (raw)

This patch series performs a decently-sized refactoring of the revision-walk
machinery. Well, "refactoring" is probably the wrong word, as I don't
actually remove the old code. Instead, when we see certain options in the
'rev_info' struct, we redirect the commit-walk logic to a new set of methods
that distribute the workload differently. By using generation numbers in the
commit-graph, we can significantly improve 'git log --graph' commands (and
the underlying 'git rev-list --topo-order').

On the Linux repository, I got the following performance results when
comparing to the previous version with or without a commit-graph:

Test: git rev-list --topo-order -100 HEAD
HEAD~1, no commit-graph: 6.80 s
HEAD~1, w/ commit-graph: 0.77 s
  HEAD, w/ commit-graph: 0.02 s

Test: git rev-list --topo-order -100 HEAD -- tools
HEAD~1, no commit-graph: 9.63 s
HEAD~1, w/ commit-graph: 6.06 s
  HEAD, w/ commit-graph: 0.06 s

If you want to read this series but are unfamiliar with the commit-graph and
generation numbers, then I recommend reading 
Documentation/technical/commit-graph.txt or a blob post [1] I wrote on the
subject. In particular, the three-part walk described in "revision.c:
refactor basic topo-order logic" is present (but underexplained) as an
animated PNG [2].

Since revision.c is an incredibly important (and old) portion of the
codebase -- and because there are so many orthogonal options in 'struct
rev_info' -- I consider this submission to be "RFC quality". That is, I am
not confident that I am not missing anything, or that my solution is the
best it can be. I did merge this branch with ds/commit-graph-with-grafts and
the "DO-NOT-MERGE: write and read commit-graph always" commit that computes
a commit-graph with every 'git commit' command. The test suite passed with
that change, available on GitHub [3]. To ensure that I cover at least the
case I think are interesting, I added tests to t6600-test-reach.sh to verify
the walks report the correct results for the three cases there (no
commit-graph, full commit-graph, and a partial commit-graph so the walk
starts at GENERATION_NUMBER_INFINITY).

One notable case that is not included in this series is the case of a
history comparison such as 'git rev-list --topo-order A..B'. The existing
code in limit_list() has ways to cut the walk short when all pending commits
are UNINTERESTING. Since this code depends on commit_list instead of the
prio_queue we are using here, I chose to leave it untouched for now. We can
revisit it in a separate series later. Since handle_commit() turns on
revs->limited when a commit is UNINTERESTING, we do not hit the new code in
this case. Removing this 'revs->limited = 1;' line yields correct results,
but the performance is worse.

This series is based on ds/reachable.

Thanks, -Stolee

[1] 
https://blogs.msdn.microsoft.com/devops/2018/07/09/supercharging-the-git-commit-graph-iii-generations/
Supercharging the Git Commit Graph III: Generations and Graph Algorithms

[2] 
https://msdnshared.blob.core.windows.net/media/2018/06/commit-graph-topo-order-b-a.png
Animation showing three-part walk

[3] https://github.com/derrickstolee/git/tree/topo-order/testA branch
containing this series along with commits to compute commit-graph in entire
test suite.

Derrick Stolee (6):
  prio-queue: add 'peek' operation
  test-reach: add run_three_modes method
  test-reach: add rev-list tests
  revision.c: begin refactoring --topo-order logic
  commit/revisions: bookkeeping before refactoring
  revision.c: refactor basic topo-order logic

 commit.c                   |  11 +-
 commit.h                   |   8 ++
 object.h                   |   4 +-
 prio-queue.c               |   9 ++
 prio-queue.h               |   6 +
 revision.c                 | 232 ++++++++++++++++++++++++++++++++++++-
 revision.h                 |   6 +
 t/helper/test-prio-queue.c |  10 +-
 t/t6600-test-reach.sh      |  98 +++++++++++++++-
 9 files changed, 361 insertions(+), 23 deletions(-)


base-commit: 6cc017431c1c48f80d1c6512fdcc9866cf4b7f55
Published-As: https://github.com/gitgitgadget/git/releases/tags/pr-25%2Fderrickstolee%2Ftopo-order%2Fprogress-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-25/derrickstolee/topo-order/progress-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/25
-- 
gitgitgadget

             reply index

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-27 20:41 Derrick Stolee via GitGitGadget [this message]
2018-08-27 20:41 ` [PATCH 1/6] prio-queue: add 'peek' operation Derrick Stolee via GitGitGadget
2018-08-27 20:41 ` [PATCH 2/6] test-reach: add run_three_modes method Derrick Stolee via GitGitGadget
2018-08-27 20:41 ` [PATCH 3/6] test-reach: add rev-list tests Derrick Stolee via GitGitGadget
2018-08-27 20:41 ` [PATCH 4/6] revision.c: begin refactoring --topo-order logic Derrick Stolee via GitGitGadget
2018-08-27 20:41 ` [PATCH 5/6] commit/revisions: bookkeeping before refactoring Derrick Stolee via GitGitGadget
2018-08-27 20:41 ` [PATCH 6/6] revision.c: refactor basic topo-order logic Derrick Stolee via GitGitGadget
2018-08-27 21:23 ` [PATCH 0/6] Use generation numbers for --topo-order Junio C Hamano
2018-09-18  4:08 ` [PATCH v2 " Derrick Stolee via GitGitGadget
2018-09-18  4:08   ` [PATCH v2 1/6] prio-queue: add 'peek' operation Derrick Stolee via GitGitGadget
2018-09-18  4:08   ` [PATCH v2 2/6] test-reach: add run_three_modes method Derrick Stolee via GitGitGadget
2018-09-18 18:02     ` SZEDER Gábor
2018-09-19 19:31       ` Junio C Hamano
2018-09-19 19:38         ` Junio C Hamano
2018-09-20 21:18           ` Junio C Hamano
2018-09-18  4:08   ` [PATCH v2 3/6] test-reach: add rev-list tests Derrick Stolee via GitGitGadget
2018-09-18  4:08   ` [PATCH v2 4/6] revision.c: begin refactoring --topo-order logic Derrick Stolee via GitGitGadget
2018-09-18  4:08   ` [PATCH v2 5/6] commit/revisions: bookkeeping before refactoring Derrick Stolee via GitGitGadget
2018-09-18  4:08   ` [PATCH v2 6/6] revision.c: refactor basic topo-order logic Derrick Stolee via GitGitGadget
2018-09-18  5:51     ` Ævar Arnfjörð Bjarmason
2018-09-18  6:05   ` [PATCH v2 0/6] Use generation numbers for --topo-order Ævar Arnfjörð Bjarmason
2018-09-21 15:47     ` Derrick Stolee
2018-09-21 17:39   ` [PATCH v3 0/7] " Derrick Stolee via GitGitGadget
2018-09-21 17:39     ` [PATCH v3 1/7] prio-queue: add 'peek' operation Derrick Stolee via GitGitGadget
2018-09-26 19:15       ` Derrick Stolee
2018-10-11 13:54       ` Jeff King
2018-09-21 17:39     ` [PATCH v3 2/7] test-reach: add run_three_modes method Derrick Stolee via GitGitGadget
2018-10-11 13:57       ` Jeff King
2018-09-21 17:39     ` [PATCH v3 3/7] test-reach: add rev-list tests Derrick Stolee via GitGitGadget
2018-10-11 13:58       ` Jeff King
2018-10-12  4:34         ` Junio C Hamano
2018-09-21 17:39     ` [PATCH v3 4/7] revision.c: begin refactoring --topo-order logic Derrick Stolee via GitGitGadget
2018-10-11 14:06       ` Jeff King
2018-10-12  6:33       ` Junio C Hamano
2018-10-12 12:32         ` Derrick Stolee
2018-10-12 16:15         ` Johannes Sixt
2018-10-13  8:05           ` Junio C Hamano
2018-09-21 17:39     ` [PATCH v3 5/7] commit/revisions: bookkeeping before refactoring Derrick Stolee via GitGitGadget
2018-10-11 14:21       ` Jeff King
2018-09-21 17:39     ` [PATCH v3 6/7] revision.h: add whitespace in flag definitions Derrick Stolee via GitGitGadget
2018-09-21 17:39     ` [PATCH v3 7/7] revision.c: refactor basic topo-order logic Derrick Stolee via GitGitGadget
2018-09-27 17:57       ` Derrick Stolee
2018-10-06 16:56         ` Jakub Narebski
2018-10-11 15:35       ` Jeff King
2018-10-11 16:21         ` Derrick Stolee
2018-10-25  9:43           ` Jeff King
2018-10-25 13:00             ` Derrick Stolee
2018-10-11 22:32       ` Stefan Beller
2018-09-21 21:22     ` [PATCH v3 0/7] Use generation numbers for --topo-order Junio C Hamano
2018-10-16 22:36     ` [PATCH v4 " Derrick Stolee via GitGitGadget
2018-10-16 22:36       ` [PATCH v4 1/7] prio-queue: add 'peek' operation Derrick Stolee via GitGitGadget
2018-10-16 22:36       ` [PATCH v4 2/7] test-reach: add run_three_modes method Derrick Stolee via GitGitGadget
2018-10-16 22:36       ` [PATCH v4 3/7] test-reach: add rev-list tests Derrick Stolee via GitGitGadget
2018-10-21 10:21         ` Jakub Narebski
2018-10-21 15:28           ` Derrick Stolee
2018-10-16 22:36       ` [PATCH v4 4/7] revision.c: begin refactoring --topo-order logic Derrick Stolee via GitGitGadget
2018-10-21 15:55         ` Jakub Narebski
2018-10-22  1:12           ` Junio C Hamano
2018-10-22  1:51             ` Derrick Stolee
2018-10-22  1:55               ` [RFC PATCH] revision.c: use new algorithm in A..B case Derrick Stolee
2018-10-25  8:28               ` [PATCH v4 4/7] revision.c: begin refactoring --topo-order logic Junio C Hamano
2018-10-26 20:56                 ` Jakub Narebski
2018-10-16 22:36       ` [PATCH v4 5/7] commit/revisions: bookkeeping before refactoring Derrick Stolee via GitGitGadget
2018-10-21 21:17         ` Jakub Narebski
2018-10-16 22:36       ` [PATCH v4 6/7] revision.c: generation-based topo-order algorithm Derrick Stolee via GitGitGadget
2018-10-22 13:37         ` Jakub Narebski
2018-10-23 13:54           ` Derrick Stolee
2018-10-26 16:55             ` Jakub Narebski
2018-10-16 22:36       ` [PATCH v4 7/7] t6012: make rev-list tests more interesting Derrick Stolee via GitGitGadget
2018-10-23 15:48         ` Jakub Narebski
2018-10-21 12:57       ` [PATCH v4 0/7] Use generation numbers for --topo-order Jakub Narebski
2018-11-01  5:21       ` Junio C Hamano
2018-11-01 13:49         ` Derrick Stolee
2018-11-01 23:54           ` Junio C Hamano
2018-11-01 13:46       ` [PATCH v5 " Derrick Stolee
2018-11-01 13:46         ` [PATCH v5 1/7] prio-queue: add 'peek' operation Derrick Stolee
2018-11-01 13:46         ` [PATCH v5 2/7] test-reach: add run_three_modes method Derrick Stolee
2018-11-01 13:46         ` [PATCH v5 3/7] test-reach: add rev-list tests Derrick Stolee
2018-11-01 13:46         ` [PATCH v5 4/7] revision.c: begin refactoring --topo-order logic Derrick Stolee
2018-11-01 13:46         ` [PATCH v5 5/7] commit/revisions: bookkeeping before refactoring Derrick Stolee
2018-11-01 13:46         ` [PATCH v5 6/7] revision.c: generation-based topo-order algorithm Derrick Stolee
2018-11-01 15:48           ` SZEDER Gábor
2018-11-01 16:12             ` Derrick Stolee
2018-11-01 13:46         ` [PATCH v5 7/7] t6012: make rev-list tests more interesting Derrick Stolee

Reply instructions:

You may reply publically 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=pull.25.git.gitgitgadget@gmail.com \
    --to=gitgitgadget@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.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

git@vger.kernel.org list mirror (unofficial, one of many)

Archives are clonable:
	git clone --mirror https://public-inbox.org/git
	git clone --mirror http://ou63pmih66umazou.onion/git
	git clone --mirror http://czquwvybam4bgbro.onion/git
	git clone --mirror http://hjrcffqmbrq6wope.onion/git

Example config snippet for mirrors

Newsgroups are available over NNTP:
	nntp://news.public-inbox.org/inbox.comp.version-control.git
	nntp://ou63pmih66umazou.onion/inbox.comp.version-control.git
	nntp://czquwvybam4bgbro.onion/inbox.comp.version-control.git
	nntp://hjrcffqmbrq6wope.onion/inbox.comp.version-control.git
	nntp://news.gmane.org/gmane.comp.version-control.git

 note: .onion URLs require Tor: https://www.torproject.org/

AGPL code for this site: git clone https://public-inbox.org/ public-inbox