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From: Patrick Steinhardt <ps@pks.im>
To: git@vger.kernel.org
Subject: [PATCH 7/8] receive-pack: skip connectivity checks on delete-only commands
Date: Wed, 19 May 2021 21:13:47 +0200	[thread overview]
Message-ID: <68c60aff0c77c562aba5613ccbb9ab33ad8e0e08.1621451532.git.ps@pks.im> (raw)
In-Reply-To: <cover.1621451532.git.ps@pks.im>

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In the case where git-receive-pack(1) receives only commands which
delete references, then per technical specification the client MUST NOT
send a packfile. As a result, we know that no new objects have been
received, which makes it a moot point to check whether all received
objects are fully connected.

Fix this by not doing a connectivity check in case there were no pushed
objects. Given that git-rev-walk(1) with only negative references will
not do any graph walk, no performance improvements are to be expected.
Conceptionally, it is still the right thing to do though.

The following tests were executed on linux.git and back up above
expectation:

Test                                     v2.32.0-rc0             HEAD
--------------------------------------------------------------------------------------------
5400.3: receive-pack clone create        1.27(1.11+0.16)         1.26(1.12+0.14) -0.8%
5400.5: receive-pack clone update        1.27(1.13+0.13)         1.27(1.11+0.16) +0.0%
5400.7: receive-pack clone reset         0.13(0.11+0.02)         0.14(0.11+0.02) +7.7%
5400.9: receive-pack clone delete        0.02(0.01+0.01)         0.02(0.00+0.01) +0.0%
5400.11: receive-pack extrarefs create   33.01(18.80+14.43)      32.63(18.52+14.24) -1.2%
5400.13: receive-pack extrarefs update   33.13(18.85+14.50)      32.82(18.85+14.29) -0.9%
5400.15: receive-pack extrarefs reset    32.90(18.82+14.32)      32.70(18.76+14.20) -0.6%
5400.17: receive-pack extrarefs delete   9.13(4.35+4.77)         8.99(4.28+4.70) -1.5%
5400.19: receive-pack empty create       223.35(640.63+127.74)   226.96(655.16+131.93) +1.6%

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 builtin/receive-pack.c | 49 ++++++++++++++++++++++++++----------------
 1 file changed, 30 insertions(+), 19 deletions(-)

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index a34742513a..b9263cec15 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -1918,11 +1918,8 @@ static void execute_commands(struct command *commands,
 			     struct shallow_info *si,
 			     const struct string_list *push_options)
 {
-	struct check_connected_options opt = CHECK_CONNECTED_INIT;
 	struct command *cmd;
 	struct iterate_data data;
-	struct async muxer;
-	int err_fd = 0;
 	int run_proc_receive = 0;
 
 	if (unpacker_error) {
@@ -1931,25 +1928,39 @@ static void execute_commands(struct command *commands,
 		return;
 	}
 
-	if (use_sideband) {
-		memset(&muxer, 0, sizeof(muxer));
-		muxer.proc = copy_to_sideband;
-		muxer.in = -1;
-		if (!start_async(&muxer))
-			err_fd = muxer.in;
-		/* ...else, continue without relaying sideband */
-	}
-
 	data.cmds = commands;
 	data.si = si;
-	opt.err_fd = err_fd;
-	opt.progress = err_fd && !quiet;
-	opt.env = tmp_objdir_env(tmp_objdir);
-	if (check_connected(iterate_receive_command_list, &data, &opt))
-		set_connectivity_errors(commands, si);
 
-	if (use_sideband)
-		finish_async(&muxer);
+	/*
+	 * If received commands only consist of deletions, then the client MUST
+	 * NOT send a packfile because there cannot be any new objects in the
+	 * first place. As a result, we do not set up a quarantine environment
+	 * because we know no new objects will be received. And that in turn
+	 * means that we can skip connectivity checks here.
+	 */
+	if (tmp_objdir) {
+		struct check_connected_options opt = CHECK_CONNECTED_INIT;
+		struct async muxer;
+		int err_fd = 0;
+
+		if (use_sideband) {
+			memset(&muxer, 0, sizeof(muxer));
+			muxer.proc = copy_to_sideband;
+			muxer.in = -1;
+			if (!start_async(&muxer))
+				err_fd = muxer.in;
+			/* ...else, continue without relaying sideband */
+		}
+
+		opt.err_fd = err_fd;
+		opt.progress = err_fd && !quiet;
+		opt.env = tmp_objdir_env(tmp_objdir);
+		if (check_connected(iterate_receive_command_list, &data, &opt))
+			set_connectivity_errors(commands, si);
+
+		if (use_sideband)
+			finish_async(&muxer);
+	}
 
 	reject_updates_to_hidden(commands);
 
-- 
2.31.1


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  parent reply	other threads:[~2021-05-19 19:13 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 19:13 [PATCH 0/8] Speed up connectivity checks via quarantine dir Patrick Steinhardt
2021-05-19 19:13 ` [PATCH 1/8] perf: fix when running with TEST_OUTPUT_DIRECTORY Patrick Steinhardt
2021-05-20  2:03   ` Chris Torek
2021-05-19 19:13 ` [PATCH 2/8] p5400: add perf tests for git-receive-pack(1) Patrick Steinhardt
2021-05-20  2:09   ` Chris Torek
2021-05-20 17:04   ` Jeff King
2021-05-21 15:03   ` SZEDER Gábor
2021-05-19 19:13 ` [PATCH 3/8] tmp-objdir: expose function to retrieve path Patrick Steinhardt
2021-05-20  0:16   ` Elijah Newren
2021-05-19 19:13 ` [PATCH 4/8] packfile: have `for_each_file_in_pack_dir()` return error codes Patrick Steinhardt
2021-05-19 19:13 ` [PATCH 5/8] object-file: allow reading loose objects without reading their contents Patrick Steinhardt
2021-05-19 19:13 ` [PATCH 6/8] connected: implement connectivity check via temporary object dirs Patrick Steinhardt
2021-05-19 19:13 ` Patrick Steinhardt [this message]
2021-05-21 18:53   ` [PATCH 7/8] receive-pack: skip connectivity checks on delete-only commands Felipe Contreras
2021-05-27 14:38     ` Jeff King
2021-05-19 19:13 ` [PATCH 8/8] receive-pack: check connectivity via quarantined objects Patrick Steinhardt
2021-05-20  2:19 ` [PATCH 0/8] Speed up connectivity checks via quarantine dir Chris Torek
2021-05-20 16:50 ` Jeff King
2021-05-20 21:45   ` Junio C Hamano
2021-05-21  9:30     ` Jeff King
2021-05-21  9:42   ` Patrick Steinhardt
2021-05-21 11:20   ` Ævar Arnfjörð Bjarmason

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