git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / Atom feed
From: Ævar Arnfjörð Bjarmason  <avarab@gmail.com>
To: git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>,
	Denton Liu <liu.denton@gmail.com>,
	Eric Sunshine <sunshine@sunshineco.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Johannes Sixt <j6t@kdbg.org>, SZEDER Gábor <szeder.dev@gmail.com>,
	Ævar Arnfjörð Bjarmason  <avarab@gmail.com>
Subject: [RFC WIP PATCH v8 11/13] rebase: eliminate side-effects from can_fast_forward()
Date: Wed,  8 May 2019 02:12:50 +0200
Message-ID: <20190508001252.15752-12-avarab@gmail.com> (raw)
In-Reply-To: <cover.1555832783.git.liu.denton@gmail.com>

The can_fast_forward() function is potentially much more expensive
than is_interactive() since it e.g. might need to call
is_linear_history().

So reversing the two looks like an obvious improvement, but doing so
reveals a previously hidden caveat: We need the can_fast_forward()
function to populate data used later, namely the "merge_bases"
variable. This has been the case since it was added in
9a48a615b4 ("builtin rebase: try to fast forward when possible",
2018-09-04).

So let's refactor it into two functions. Now we'll always call
populate_merge_bases(), and then only call can_fast_forward() if
is_interactive() is false, making this both faster in pathological
cases, and more importantly easier to follow.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/rebase.c | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/builtin/rebase.c b/builtin/rebase.c
index ae6b9b42b8..cb5d7fcb53 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -878,24 +878,30 @@ static int is_linear_history(struct commit *from, struct commit *to)
 	return 1;
 }
 
-static int can_fast_forward(struct commit *onto, struct commit *upstream,
+static void populate_merge_bases(struct commit *head, struct commit *onto,
+				 struct commit_list *merge_bases,
+				 struct object_id *merge_base)
+{
+	merge_bases = get_merge_bases(onto, head);
+	if (!merge_bases || merge_bases->next) {
+		oidcpy(merge_base, &null_oid);
+		return;
+	}
+	oidcpy(merge_base, &merge_bases->item->object.oid);
+}
+
+static int can_fast_forward(struct commit *head,
+			    struct commit *onto, struct commit *upstream,
 			    struct commit *restrict_revision,
-			    struct object_id *head_oid, struct object_id *merge_base)
+			    struct object_id *head_oid,
+			    struct commit_list *merge_bases,
+			    struct object_id *merge_base)
 {
-	struct commit *head = lookup_commit(the_repository, head_oid);
-	struct commit_list *merge_bases = NULL;
 	int res = 0;
 
 	if (!head)
 		goto done;
 
-	merge_bases = get_merge_bases(onto, head);
-	if (!merge_bases || merge_bases->next) {
-		oidcpy(merge_base, &null_oid);
-		goto done;
-	}
-
-	oidcpy(merge_base, &merge_bases->item->object.oid);
 	if (!oideq(merge_base, &onto->object.oid))
 		goto done;
 
@@ -1154,6 +1160,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		OPT_END(),
 	};
 	int i;
+	struct commit *head_commit;
+	struct commit_list *merge_bases = NULL;
 
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(builtin_rebase_usage,
@@ -1703,9 +1711,14 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 	 * with new commits recreated by replaying their changes. This
 	 * optimization must not be done if this is an interactive rebase.
 	 */
-	if (can_fast_forward(options.onto, options.upstream, options.restrict_revision,
-		    &options.orig_head, &merge_base) &&
-	    !is_interactive(&options)) {
+	head_commit = lookup_commit(the_repository, &options.orig_head);
+	if (head_commit)
+		populate_merge_bases(head_commit, options.onto, merge_bases,
+				     &merge_base);
+	if (!is_interactive(&options) &&
+	    can_fast_forward(head_commit, options.onto, options.upstream,
+			     options.restrict_revision, &options.orig_head,
+			     merge_bases, &merge_base)) {
 		int flag;
 
 		if (!(options.flags & REBASE_FORCE)) {
-- 
2.21.0.1020.gf2820cf01a


  parent reply index

Thread overview: 123+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-23 15:25 [PATCH 0/3] rebase: learn --keep-base Denton Liu
2019-03-23 15:25 ` [PATCH 1/3] rebase: teach rebase --keep-base Denton Liu
2019-03-24  3:46   ` Eric Sunshine
2019-03-24 13:20   ` Junio C Hamano
2019-03-25  0:06     ` Denton Liu
2019-03-25  5:41       ` Denton Liu
2019-04-01 10:45         ` Junio C Hamano
2019-03-24 13:37   ` Junio C Hamano
2019-03-25  5:47   ` Denton Liu
2019-03-25 18:50   ` Johannes Schindelin
2019-03-25 19:29     ` Denton Liu
2019-03-26 13:27       ` Johannes Schindelin
2019-03-23 15:25 ` [PATCH 2/3] t3416: test " Denton Liu
2019-03-23 15:25 ` [PATCH 3/3] git-rebase.txt: document --keep-base option Denton Liu
2019-03-24 13:15 ` [PATCH 0/3] rebase: learn --keep-base Junio C Hamano
2019-03-25  0:04   ` Denton Liu
2019-04-01 10:45     ` Junio C Hamano
2019-03-26 14:35 ` Ævar Arnfjörð Bjarmason
2019-03-26 17:50   ` Denton Liu
2019-03-26 20:35     ` Ævar Arnfjörð Bjarmason
2019-03-26 21:30       ` Denton Liu
2019-03-27 15:39         ` Ævar Arnfjörð Bjarmason
2019-03-28 22:17 ` [PATCH v2] rebase: teach rebase --keep-base Denton Liu
2019-03-28 23:13   ` Ævar Arnfjörð Bjarmason
2019-03-29 15:47   ` Johannes Schindelin
2019-03-29 17:52     ` Denton Liu
2019-04-01 10:46     ` Junio C Hamano
2019-04-01 20:51   ` [PATCH v3 0/4] " Denton Liu
2019-04-01 20:51     ` [PATCH v3 1/4] t3431: add rebase --fork-point tests Denton Liu
2019-04-04 20:28       ` Denton Liu
2019-04-05 11:15       ` SZEDER Gábor
2019-04-08  4:38         ` Junio C Hamano
2019-04-05 14:55       ` Johannes Schindelin
2019-04-05 17:25         ` Denton Liu
2019-04-05 17:51           ` Johannes Sixt
2019-04-05 18:51             ` Johannes Schindelin
2019-04-05 20:19               ` Johannes Schindelin
2019-04-05 21:10                 ` SZEDER Gábor
2019-04-01 20:51     ` [PATCH v3 2/4] t3432: test rebase fast-forward behavior Denton Liu
2019-04-01 20:52     ` [PATCH v3 3/4] rebase: fast-forward --onto in more cases Denton Liu
2019-04-02  1:25       ` Junio C Hamano
2019-04-02  1:48         ` Junio C Hamano
2019-04-02  4:44           ` Denton Liu
2019-04-01 20:52     ` [PATCH v3 4/4] rebase: teach rebase --keep-base Denton Liu
2019-04-05 21:39     ` [PATCH v4 0/4] " Denton Liu
2019-04-05 21:40       ` [PATCH v4 1/4] t3431: add rebase --fork-point tests Denton Liu
2019-04-05 21:40       ` [PATCH v4 2/4] t3432: test rebase fast-forward behavior Denton Liu
2019-04-05 21:40       ` [PATCH v4 3/4] rebase: fast-forward --onto in more cases Denton Liu
2019-04-05 21:40       ` [PATCH v4 4/4] rebase: teach rebase --keep-base Denton Liu
2019-04-15 22:29       ` [PATCH v5 0/5] " Denton Liu
2019-04-15 22:29         ` [PATCH v5 1/5] t3431: add rebase --fork-point tests Denton Liu
2019-04-15 22:29         ` [PATCH v5 2/5] t3432: test rebase fast-forward behavior Denton Liu
2019-04-15 22:29         ` [PATCH v5 3/5] rebase: fast-forward --onto in more cases Denton Liu
2019-04-16  6:26           ` Junio C Hamano
2019-04-16 13:59           ` Phillip Wood
2019-04-17  6:44             ` Denton Liu
2019-04-17 14:14               ` Phillip Wood
2019-04-19 17:08           ` Denton Liu
2019-04-15 22:29         ` [PATCH v5 4/5] rebase: fast-forward --fork-point " Denton Liu
2019-04-15 22:29         ` [PATCH v5 5/5] rebase: teach rebase --keep-base Denton Liu
2019-04-17 18:01       ` [PATCH v6 0/5] " Denton Liu
2019-04-17 18:01         ` [PATCH v6 1/6] t3431: add rebase --fork-point tests Denton Liu
2019-04-17 18:01         ` [PATCH v6 2/6] t3432: test rebase fast-forward behavior Denton Liu
2019-04-17 18:01         ` [PATCH v6 3/6] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-04-17 18:01         ` [PATCH v6 4/6] rebase: fast-forward --onto in more cases Denton Liu
2019-04-17 19:59           ` Phillip Wood
2019-04-17 18:01         ` [PATCH v6 5/6] rebase: fast-forward --fork-point " Denton Liu
2019-04-17 18:01         ` [PATCH v6 6/6] rebase: teach rebase --keep-base Denton Liu
2019-04-21  8:11         ` [PATCH v7 0/6] rebase: learn --keep-base Denton Liu
2019-04-21  8:11           ` [PATCH v7 1/6] t3431: add rebase --fork-point tests Denton Liu
2019-04-23 23:12             ` Denton Liu
2019-04-21  8:11           ` [PATCH v7 2/6] t3432: test rebase fast-forward behavior Denton Liu
2019-04-21  8:11           ` [PATCH v7 3/6] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-04-21  8:11           ` [PATCH v7 4/6] rebase: fast-forward --onto in more cases Denton Liu
2019-04-21  8:11           ` [PATCH v7 5/6] rebase: fast-forward --fork-point " Denton Liu
2019-04-21  8:11           ` [PATCH v7 6/6] rebase: teach rebase --keep-base Denton Liu
2019-05-08  0:12           ` [RFC WIP PATCH v8 00/13] learn --keep-base & more Ævar Arnfjörð Bjarmason
2019-05-08  3:57             ` Junio C Hamano
2019-07-19 19:14               ` Junio C Hamano
2019-07-19 21:01                 ` Denton Liu
2019-08-25  9:11             ` [PATCH v9 0/9] rebase: learn --keep-base and improvements on fast-forward behaviour Denton Liu
2019-08-25  9:11               ` [PATCH v9 1/9] t3431: add rebase --fork-point tests Denton Liu
2019-08-25  9:12               ` [PATCH v9 2/9] t3432: test rebase fast-forward behavior Denton Liu
2019-08-25  9:12               ` [PATCH v9 3/9] t3432: distinguish "noop-same" v.s. "work-same" in "same head" tests Denton Liu
2019-08-25  9:12               ` [PATCH v9 4/9] t3432: test for --no-ff's interaction with fast-forward Denton Liu
2019-08-25  9:12               ` [PATCH v9 5/9] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-08-25 13:17                 ` Pratyush Yadav
2019-08-26 23:17                   ` Denton Liu
2019-08-25  9:12               ` [PATCH v9 6/9] rebase: fast-forward --onto in more cases Denton Liu
2019-08-25  9:12               ` [PATCH v9 7/9] rebase: fast-forward --fork-point " Denton Liu
2019-08-25  9:12               ` [PATCH v9 8/9] rebase tests: test linear branch topology Denton Liu
2019-08-25  9:12               ` [PATCH v9 9/9] rebase: teach rebase --keep-base Denton Liu
2019-08-25 22:59                 ` Philip Oakley
2019-08-26 19:37               ` [PATCH v9 0/9] rebase: learn --keep-base and improvements on fast-forward behaviour Junio C Hamano
2019-08-27  5:37               ` [PATCH v10 " Denton Liu
2019-08-27  5:37                 ` [PATCH v10 1/9] t3431: add rebase --fork-point tests Denton Liu
2019-08-27  5:37                 ` [PATCH v10 2/9] t3432: test rebase fast-forward behavior Denton Liu
2019-08-27  5:37                 ` [PATCH v10 3/9] t3432: distinguish "noop-same" v.s. "work-same" in "same head" tests Denton Liu
2019-08-27  5:37                 ` [PATCH v10 4/9] t3432: test for --no-ff's interaction with fast-forward Denton Liu
2019-08-27  8:11                   ` SZEDER Gábor
2019-08-27  5:37                 ` [PATCH v10 5/9] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-08-27  5:37                 ` [PATCH v10 6/9] rebase: fast-forward --onto in more cases Denton Liu
2019-08-27  5:38                 ` [PATCH v10 7/9] rebase: fast-forward --fork-point " Denton Liu
2019-08-27  5:38                 ` [PATCH v10 8/9] rebase tests: test linear branch topology Denton Liu
2019-08-27  5:38                 ` [PATCH v10 9/9] rebase: teach rebase --keep-base Denton Liu
2019-05-08  0:12           ` [RFC WIP PATCH v8 01/13] t3431: add rebase --fork-point tests Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 02/13] t3432: test rebase fast-forward behavior Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 03/13] t3432: distinguish "noop-same" v.s. "work-same" in "same head" tests Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 04/13] t3432: test for --no-ff's interaction with fast-forward Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 05/13] rebase: refactor can_fast_forward into goto tower Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 06/13] rebase: fast-forward --onto in more cases Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 07/13] rebase: fast-forward --fork-point " Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 08/13] rebase: teach rebase --keep-base Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 09/13] rebase tests: test linear branch topology Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 10/13] rebase: don't rebase linear topology with --fork-point Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` Ævar Arnfjörð Bjarmason [this message]
2019-05-17 21:16             ` [RFC WIP PATCH v8 11/13] rebase: eliminate side-effects from can_fast_forward() Johannes Schindelin
2019-05-08  0:12           ` [RFC WIP PATCH v8 12/13] rebase: add a should_fast_forward() utility function Ævar Arnfjörð Bjarmason
2019-05-08  0:12           ` [RFC WIP PATCH v8 13/13] WIP: can_fast_forward() support for --preserve-merges and --rebase-merges Ævar Arnfjörð Bjarmason
2019-05-17 22:02             ` Johannes Schindelin
2019-04-06 19:44     ` [PATCH v3 0/4] rebase: teach rebase --keep-base Ævar Arnfjörð Bjarmason
2019-04-06 20:38       ` Denton Liu
2019-04-13 21:10         ` Ævar Arnfjörð Bjarmason

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=20190508001252.15752-12-avarab@gmail.com \
    --to=avarab@gmail.com \
    --cc=Johannes.Schindelin@gmx.de \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=j6t@kdbg.org \
    --cc=liu.denton@gmail.com \
    --cc=sunshine@sunshineco.com \
    --cc=szeder.dev@gmail.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.git