[PATCH 7/7] builtin/maintenance: fix auto-detach with non-standard tasks

Patrick Steinhardt
2024-08-13T07:18:02Z

In the past, we used to execute `git gc --auto` as part of our automatic
housekeeping routines. As git-gc(1) may require quite some time to
perform the housekeeping, it knows to detach itself and run in the
background so that the user can continue their work.

Eventually, we refactored our automatic housekeeping to instead use the
more flexible git-maintenance(1) command. The upside of this new infra
is that the user can configure which maintenance tasks are performed, at
least to a certain degree. So while it continues to run git-gc(1) by
default, it can also be adapted to e.g. use git-multi-pack-index(1) for
maintenance of the object database.

The auto-detach of the new infra is somewhat broken though once the user
configures non-standard tasks. The problem is essentially that we detach
at the wrong level in the process hierarchy: git-maintenance(1) never
detaches itself, but instead it continues to be git-gc(1) which does.

When configured to only run the git-gc(1) maintenance task, then the
result is basically the same as before. But when configured to run other
tasks, then git-maintenance(1) will wait for these to run to completion.
Even worse, it may be that git-gc(1) runs concurrently with other
housekeeping tasks, stomping on each others feet.

Fix this bug by asking git-gc(1) to not detach when it is being invoked
via git-maintenance(1). Instead, the latter command now respects a new
config "maintenance.autoDetach", the equivalent of "gc.autoDetach", and
detaches itself into the background if not told otherwise. This should
continue to behave the same for all users which use the git-gc(1) task,
only. For others though, it means that we now properly perform all tasks
in the background.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
builtin/gc.c | 1 +
run-command.c | 12 ++++++++++-
t/t5616-partial-clone.sh | 6 +++---
t/t7900-maintenance.sh | 43 +++++++++++++++++++++++++++++++---------
4 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index 63106e2028..bafee330a2 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -1063,6 +1063,7 @@ static int maintenance_task_gc(struct maintenance_run_opts *opts,
strvec_push(&child.args, "--quiet");
else
strvec_push(&child.args, "--no-quiet");
+ strvec_push(&child.args, "--no-detach");

return run_command(&child);
}
diff --git a/run-command.c b/run-command.c
index 45ba544932..94f2f3079f 100644
--- a/run-command.c
+++ b/run-command.c
@@ -1808,16 +1808,26 @@ void run_processes_parallel(const struct run_process_parallel_opts *opts)

int prepare_auto_maintenance(int quiet, struct child_process *maint)
{
- int enabled;
+ int enabled, auto_detach;

if (!git_config_get_bool("maintenance.auto", &enabled) &&
!enabled)
return 0;

+ /*
+ * When `maintenance.autoDetach` isn't set, then we fall back to
+ * honoring `gc.autoDetach`. This is somewhat weird, but required to
+ * retain behaviour from when we used to run git-gc(1) here.
+ */
+ if (git_config_get_bool("maintenance.autodetach", &auto_detach) &&
+ git_config_get_bool("gc.autodetach", &auto_detach))
+ auto_detach = 1;
+
maint->git_cmd = 1;
maint->close_object_store = 1;
strvec_pushl(&maint->args, "maintenance", "run", "--auto", NULL);
strvec_push(&maint->args, quiet ? "--quiet" : "--no-quiet");
+ strvec_push(&maint->args, auto_detach ? "--detach" : "--no-detach");

return 1;
}
diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index 2da7291e37..8415884754 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -229,7 +229,7 @@ test_expect_success 'fetch --refetch triggers repacking' '

GIT_TRACE2_EVENT="$PWD/trace1.event" \
git -C pc1 fetch --refetch origin &&
- test_subcommand git maintenance run --auto --no-quiet <trace1.event &&
+ test_subcommand git maintenance run --auto --no-quiet --detach <trace1.event &&
grep \"param\":\"gc.autopacklimit\",\"value\":\"1\" trace1.event &&
grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"-1\" trace1.event &&

@@ -238,7 +238,7 @@ test_expect_success 'fetch --refetch triggers repacking' '
-c gc.autoPackLimit=0 \
-c maintenance.incremental-repack.auto=1234 \
-C pc1 fetch --refetch origin &&
- test_subcommand git maintenance run --auto --no-quiet <trace2.event &&
+ test_subcommand git maintenance run --auto --no-quiet --detach <trace2.event &&
grep \"param\":\"gc.autopacklimit\",\"value\":\"0\" trace2.event &&
grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"-1\" trace2.event &&

@@ -247,7 +247,7 @@ test_expect_success 'fetch --refetch triggers repacking' '
-c gc.autoPackLimit=1234 \
-c maintenance.incremental-repack.auto=0 \
-C pc1 fetch --refetch origin &&
- test_subcommand git maintenance run --auto --no-quiet <trace3.event &&
+ test_subcommand git maintenance run --auto --no-quiet --detach <trace3.event &&
grep \"param\":\"gc.autopacklimit\",\"value\":\"1\" trace3.event &&
grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"0\" trace3.event
'
diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh
index 771525aa4b..06ab43cfb5 100755
--- a/t/t7900-maintenance.sh
+++ b/t/t7900-maintenance.sh
@@ -49,22 +49,47 @@ test_expect_success 'run [--auto|--quiet]' '
git maintenance run --auto 2>/dev/null &&
GIT_TRACE2_EVENT="$(pwd)/run-no-quiet.txt" \
git maintenance run --no-quiet 2>/dev/null &&
- test_subcommand git gc --quiet <run-no-auto.txt &&
- test_subcommand ! git gc --auto --quiet <run-auto.txt &&
- test_subcommand git gc --no-quiet <run-no-quiet.txt
+ test_subcommand git gc --quiet --no-detach <run-no-auto.txt &&
+ test_subcommand ! git gc --auto --quiet --no-detach <run-auto.txt &&
+ test_subcommand git gc --no-quiet --no-detach <run-no-quiet.txt
'

test_expect_success 'maintenance.auto config option' '
GIT_TRACE2_EVENT="$(pwd)/default" git commit --quiet --allow-empty -m 1 &&
- test_subcommand git maintenance run --auto --quiet <default &&
+ test_subcommand git maintenance run --auto --quiet --detach <default &&
GIT_TRACE2_EVENT="$(pwd)/true" \
git -c maintenance.auto=true \
commit --quiet --allow-empty -m 2 &&
- test_subcommand git maintenance run --auto --quiet <true &&
+ test_subcommand git maintenance run --auto --quiet --detach <true &&
GIT_TRACE2_EVENT="$(pwd)/false" \
git -c maintenance.auto=false \
commit --quiet --allow-empty -m 3 &&
- test_subcommand ! git maintenance run --auto --quiet <false
+ test_subcommand ! git maintenance run --auto --quiet --detach <false
+'
+
+for cfg in maintenance.autoDetach gc.autoDetach
+do
+ test_expect_success "$cfg=true config option" '
+ test_when_finished "rm -f trace" &&
+ test_config $cfg true &&
+ GIT_TRACE2_EVENT="$(pwd)/trace" git commit --quiet --allow-empty -m 1 &&
+ test_subcommand git maintenance run --auto --quiet --detach <trace
+ '
+
+ test_expect_success "$cfg=false config option" '
+ test_when_finished "rm -f trace" &&
+ test_config $cfg false &&
+ GIT_TRACE2_EVENT="$(pwd)/trace" git commit --quiet --allow-empty -m 1 &&
+ test_subcommand git maintenance run --auto --quiet --no-detach <trace
+ '
+done
+
+test_expect_success "maintenance.autoDetach overrides gc.autoDetach" '
+ test_when_finished "rm -f trace" &&
+ test_config maintenance.autoDetach false &&
+ test_config gc.autoDetach true &&
+ GIT_TRACE2_EVENT="$(pwd)/trace" git commit --quiet --allow-empty -m 1 &&
+ test_subcommand git maintenance run --auto --quiet --no-detach <trace
'

test_expect_success 'register uses XDG_CONFIG_HOME config if it exists' '
@@ -129,9 +154,9 @@ test_expect_success 'run --task=<task>' '
git maintenance run --task=commit-graph 2>/dev/null &&
GIT_TRACE2_EVENT="$(pwd)/run-both.txt" \
git maintenance run --task=commit-graph --task=gc 2>/dev/null &&
- test_subcommand ! git gc --quiet <run-commit-graph.txt &&
- test_subcommand git gc --quiet <run-gc.txt &&
- test_subcommand git gc --quiet <run-both.txt &&
+ test_subcommand ! git gc --quiet --no-detach <run-commit-graph.txt &&
+ test_subcommand git gc --quiet --no-detach <run-gc.txt &&
+ test_subcommand git gc --quiet --no-detach <run-both.txt &&
test_subcommand git commit-graph write --split --reachable --no-progress <run-commit-graph.txt &&
test_subcommand ! git commit-graph write --split --reachable --no-progress <run-gc.txt &&
test_subcommand git commit-graph write --split --reachable --no-progress <run-both.txt
--
2.46.0.46.g406f326d27.dirty