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From: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Jonathan Tan <jonathantanmy@google.com>,
	Derrick Stolee <derrickstolee@github.com>,
	Derrick Stolee <dstolee@microsoft.com>
Subject: [PATCH v5 07/11] maintenance: take a lock on the objects directory
Date: Thu, 17 Sep 2020 18:11:48 +0000	[thread overview]
Message-ID: <1a0a3eebb825ac3eabfdd86f82ed7ef6abb454c5.1600366313.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.695.v5.git.1600366313.gitgitgadget@gmail.com>

From: Derrick Stolee <dstolee@microsoft.com>

Performing maintenance on a Git repository involves writing data to the
.git directory, which is not safe to do with multiple writers attempting
the same operation. Ensure that only one 'git maintenance' process is
running at a time by holding a file-based lock. Simply the presence of
the .git/maintenance.lock file will prevent future maintenance. This
lock is never committed, since it does not represent meaningful data.
Instead, it is only a placeholder.

If the lock file already exists, then no maintenance tasks are
attempted. This will become very important later when we implement the
'prefetch' task, as this is our stop-gap from creating a recursive process
loop between 'git fetch' and 'git maintenance run --auto'.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/gc.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/builtin/gc.c b/builtin/gc.c
index 00fff59bdb..7ba9c6f7c9 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -798,6 +798,25 @@ static int maintenance_run_tasks(struct maintenance_run_opts *opts)
 {
 	int i, found_selected = 0;
 	int result = 0;
+	struct lock_file lk;
+	struct repository *r = the_repository;
+	char *lock_path = xstrfmt("%s/maintenance", r->objects->odb->path);
+
+	if (hold_lock_file_for_update(&lk, lock_path, LOCK_NO_DEREF) < 0) {
+		/*
+		 * Another maintenance command is running.
+		 *
+		 * If --auto was provided, then it is likely due to a
+		 * recursive process stack. Do not report an error in
+		 * that case.
+		 */
+		if (!opts->auto_flag && !opts->quiet)
+			warning(_("lock file '%s' exists, skipping maintenance"),
+				lock_path);
+		free(lock_path);
+		return 0;
+	}
+	free(lock_path);
 
 	for (i = 0; !found_selected && i < TASK__COUNT; i++)
 		found_selected = tasks[i].selected_order >= 0;
@@ -818,6 +837,7 @@ static int maintenance_run_tasks(struct maintenance_run_opts *opts)
 		}
 	}
 
+	rollback_lock_file(&lk);
 	return result;
 }
 
-- 
gitgitgadget


  parent reply	other threads:[~2020-09-17 18:18 UTC|newest]

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-06 15:48 [PATCH 00/11] Maintenance I: Command, gc and commit-graph tasks Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 01/11] maintenance: create basic maintenance runner Derrick Stolee via GitGitGadget
2020-08-07 22:16   ` Martin Ågren
2020-08-12 21:03   ` Jonathan Nieder
2020-08-12 22:07     ` Junio C Hamano
2020-08-12 22:50       ` Jonathan Nieder
2020-08-14  1:05     ` Derrick Stolee
2020-08-06 15:48 ` [PATCH 02/11] maintenance: add --quiet option Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 03/11] maintenance: replace run_auto_gc() Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 04/11] maintenance: initialize task array Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 05/11] maintenance: add commit-graph task Derrick Stolee via GitGitGadget
2020-08-07 22:29   ` Martin Ågren
2020-08-12 13:30     ` Derrick Stolee
2020-08-14 12:23       ` Martin Ågren
2020-08-06 15:48 ` [PATCH 06/11] maintenance: add --task option Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 07/11] maintenance: take a lock on the objects directory Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 08/11] maintenance: create maintenance.<task>.enabled config Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 09/11] maintenance: use pointers to check --auto Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 10/11] maintenance: add auto condition for commit-graph task Derrick Stolee via GitGitGadget
2020-08-06 15:48 ` [PATCH 11/11] maintenance: add trace2 regions for task execution Derrick Stolee via GitGitGadget
2020-08-18 14:22 ` [PATCH v2 00/11] Maintenance I: Command, gc and commit-graph tasks Derrick Stolee via GitGitGadget
2020-08-18 14:22   ` [PATCH v2 01/11] maintenance: create basic maintenance runner Derrick Stolee via GitGitGadget
2020-08-18 14:22   ` [PATCH v2 02/11] maintenance: add --quiet option Derrick Stolee via GitGitGadget
2020-08-18 14:23   ` [PATCH v2 03/11] maintenance: replace run_auto_gc() Derrick Stolee via GitGitGadget
2020-08-18 14:23   ` [PATCH v2 04/11] maintenance: initialize task array Derrick Stolee via GitGitGadget
2020-08-18 23:46     ` Jonathan Tan
2020-08-18 14:23   ` [PATCH v2 05/11] maintenance: add commit-graph task Derrick Stolee via GitGitGadget
2020-08-18 23:51     ` Jonathan Tan
2020-08-19 15:04       ` Derrick Stolee
2020-08-19 17:43         ` Jonathan Tan
2020-08-18 14:23   ` [PATCH v2 06/11] maintenance: add --task option Derrick Stolee via GitGitGadget
2020-08-19  0:00     ` Jonathan Tan
2020-08-19  0:36       ` Junio C Hamano
2020-08-19 15:09         ` Derrick Stolee
2020-08-19 17:35           ` Jonathan Tan
2020-08-18 14:23   ` [PATCH v2 07/11] maintenance: take a lock on the objects directory Derrick Stolee via GitGitGadget
2020-08-19  0:04     ` Jonathan Tan
2020-08-19 15:10       ` Derrick Stolee
2020-08-18 14:23   ` [PATCH v2 08/11] maintenance: create maintenance.<task>.enabled config Derrick Stolee via GitGitGadget
2020-08-18 14:23   ` [PATCH v2 09/11] maintenance: use pointers to check --auto Derrick Stolee via GitGitGadget
2020-08-18 14:23   ` [PATCH v2 10/11] maintenance: add auto condition for commit-graph task Derrick Stolee via GitGitGadget
2020-08-19  0:09     ` Jonathan Tan
2020-08-19 15:15       ` Derrick Stolee
2020-08-18 14:23   ` [PATCH v2 11/11] maintenance: add trace2 regions for task execution Derrick Stolee via GitGitGadget
2020-08-19  0:11     ` Jonathan Tan
2020-08-18 20:18   ` [PATCH v2 00/11] Maintenance I: Command, gc and commit-graph tasks Junio C Hamano
2020-08-19 14:51     ` Derrick Stolee
2020-08-25 18:33   ` [PATCH v3 " Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 01/11] maintenance: create basic maintenance runner Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 02/11] maintenance: add --quiet option Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 03/11] maintenance: replace run_auto_gc() Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 04/11] maintenance: initialize task array Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 05/11] maintenance: add commit-graph task Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 06/11] maintenance: add --task option Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 07/11] maintenance: take a lock on the objects directory Derrick Stolee via GitGitGadget
2020-08-26 23:02       ` Jonathan Tan
2020-08-25 18:33     ` [PATCH v3 08/11] maintenance: create maintenance.<task>.enabled config Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 09/11] maintenance: use pointers to check --auto Derrick Stolee via GitGitGadget
2020-08-25 18:33     ` [PATCH v3 10/11] maintenance: add auto condition for commit-graph task Derrick Stolee via GitGitGadget
2020-08-26 23:02       ` Jonathan Tan
2020-08-26 23:56         ` Junio C Hamano
2020-08-25 18:33     ` [PATCH v3 11/11] maintenance: add trace2 regions for task execution Derrick Stolee via GitGitGadget
2020-09-04 13:09     ` [PATCH v4 00/11] Maintenance I: Command, gc and commit-graph tasks Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 01/11] maintenance: create basic maintenance runner Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 02/11] maintenance: add --quiet option Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 03/11] maintenance: replace run_auto_gc() Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 04/11] maintenance: initialize task array Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 05/11] maintenance: add commit-graph task Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 06/11] maintenance: add --task option Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 07/11] maintenance: take a lock on the objects directory Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 08/11] maintenance: create maintenance.<task>.enabled config Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 09/11] maintenance: use pointers to check --auto Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 10/11] maintenance: add auto condition for commit-graph task Derrick Stolee via GitGitGadget
2020-09-04 13:09       ` [PATCH v4 11/11] maintenance: add trace2 regions for task execution Derrick Stolee via GitGitGadget
2020-09-17 18:11       ` [PATCH v5 00/11] Maintenance I: Command, gc and commit-graph tasks Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 01/11] maintenance: create basic maintenance runner Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 02/11] maintenance: add --quiet option Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 03/11] maintenance: replace run_auto_gc() Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 04/11] maintenance: initialize task array Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 05/11] maintenance: add commit-graph task Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 06/11] maintenance: add --task option Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` Derrick Stolee via GitGitGadget [this message]
2020-09-21 13:36           ` [PATCH v5 07/11] maintenance: take a lock on the objects directory Ævar Arnfjörð Bjarmason
2020-09-21 13:43             ` Derrick Stolee
2020-09-21 19:29               ` Junio C Hamano
2020-09-17 18:11         ` [PATCH v5 08/11] maintenance: create maintenance.<task>.enabled config Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 09/11] maintenance: use pointers to check --auto Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 10/11] maintenance: add auto condition for commit-graph task Derrick Stolee via GitGitGadget
2020-09-17 18:11         ` [PATCH v5 11/11] maintenance: add trace2 regions for task execution Derrick Stolee via GitGitGadget
2020-09-17 18:35         ` [PATCH v5 00/11] Maintenance I: Command, gc and commit-graph tasks Junio C Hamano
2020-09-18 13:14           ` Johannes Schindelin

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