[1/2] maintenance: set log.excludeDecoration durin prefetch

Commit Message

Derrick Stolee Jan. 18, 2021, 3:23 a.m. UTC

From: Derrick Stolee <[e-mail]>

The 'prefetch' task fetches refs from all remotes and places them in the
refs/prefetch/<remote>/ refspace. As this task is intended to run in the
background, this allows users to keep their local data very close to the
remote servers' data while not updating the users' understanding of the
remote refs in refs/remotes/<remote>/.

However, this can clutter 'git log' decorations with copies of the refs
with the full name 'refs/prefetch/<remote>/<branch>'.

The log.excludeDecoration config option was added in a6be5e67 (log: add
log.excludeDecoration config option, 2020-05-16) for exactly this
purpose.

Ensure we set this only for users that would benefit from it by
assigning it at the beginning of the prefetch task. Other alternatives
would be during 'git maintenance register' or 'git maintenance start',
but those might assign the config even when the prefetch task is
disabled by existing config. Further, users could run 'git maintenance
run --task=prefetch' using their own scripting or scheduling. This
provides the best coverage to automatically update the config when
valuable.

It is improbable, but possible, that users might want to run the
prefetch task _and_ see these refs in their log decorations. This seems
incredibly unlikely to me, but users can always opt-in on a
command-by-command basis using --decorate-refs=refs/prefetch/.

Test that this works in a few cases. In particular, ensure that our
assignment of log.excludeDecoration=refs/prefetch/ is additive to other
existing exclusions. Further, ensure we do not add multiple copies in
multiple runs.

Signed-off-by: Derrick Stolee <[e-mail]>
---
 builtin/gc.c           |  6 ++++++
 t/t7900-maintenance.sh | 26 +++++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

Comments

Taylor Blau Jan. 18, 2021, 3:57 p.m. UTC | #1

Not related to the patch below, but in the subject line: s/durin/\0g/.

On Mon, Jan 18, 2021 at 03:23:35AM +0000, Derrick Stolee via GitGitGadget wrote:
> diff --git a/builtin/gc.c b/builtin/gc.c
> index b315b2ad588..54bae7f0c4c 100644
> --- a/builtin/gc.c
> +++ b/builtin/gc.c
> @@ -897,6 +897,12 @@ static int maintenance_task_prefetch(struct maintenance_run_opts *opts)
>  	struct string_list_item *item;
>  	struct string_list remotes = STRING_LIST_INIT_DUP;
>
> +	git_config_set_multivar_gently("log.excludedecoration",
> +					"refs/prefetch/",
> +					"refs/prefetch/",
> +					CONFIG_FLAGS_FIXED_VALUE |
> +					CONFIG_FLAGS_MULTI_REPLACE);
> +

OK; this is a good way to ensure that you're not constantly appending
'refs/prefetch' into the config.

I did notice that we have a 'remotes' string list just above, so I
suppose we could only ignore 'refs/prefetch/<remote>' for just the
remotes that we know about, but I doubt that this would be all that
useful. (I.e., are there really users that are using refs/prefetch
already and don't want to hide the parts of it that aren't managed by
maintenance? Doubtful.)

> +test_expect_success 'prefetch and existing log.excludeDecoration values' '
> +	git config --unset-all log.excludeDecoration &&
> +	git config log.excludeDecoration refs/remotes/remote1/ &&
> +	git maintenance run --task=prefetch &&
> +
> +	git config --get-all log.excludeDecoration >out &&
> +	grep refs/remotes/remote1/ out &&
> +	grep refs/prefetch/ out &&
> +
> +	git log --oneline --decorate --all >log &&
> +	! grep "prefetch" log &&
> +	! grep "remote1" log &&
> +	grep "remote2" log &&
> +
> +	# a second run does not change the config
> +	git maintenance run --task=prefetch &&
> +	git log --oneline --decorate --all >log2 &&
> +	test_cmp log log2

Great, this test matches what I would expect. Thank you!

Thanks,
Taylor

Patch

diff --git a/builtin/gc.c b/builtin/gc.c
index b315b2ad588..54bae7f0c4c 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -897,6 +897,12 @@  static int maintenance_task_prefetch(struct maintenance_run_opts *opts)
 	struct string_list_item *item;
 	struct string_list remotes = STRING_LIST_INIT_DUP;
 
+	git_config_set_multivar_gently("log.excludedecoration",
+					"refs/prefetch/",
+					"refs/prefetch/",
+					CONFIG_FLAGS_FIXED_VALUE |
+					CONFIG_FLAGS_MULTI_REPLACE);
+
 	if (for_each_remote(append_remote, &remotes)) {
 		error(_("failed to fill remotes"));
 		result = 1;
diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh
index 1074009cc05..f9031cbb44b 100755
--- a/t/t7900-maintenance.sh
+++ b/t/t7900-maintenance.sh
@@ -149,7 +149,31 @@  test_expect_success 'prefetch multiple remotes' '
 	git log prefetch/remote2/two &&
 	git fetch --all &&
 	test_cmp_rev refs/remotes/remote1/one refs/prefetch/remote1/one &&
-	test_cmp_rev refs/remotes/remote2/two refs/prefetch/remote2/two
+	test_cmp_rev refs/remotes/remote2/two refs/prefetch/remote2/two &&
+
+	test_cmp_config refs/prefetch/ log.excludedecoration &&
+	git log --oneline --decorate --all >log &&
+	! grep "prefetch" log
+'
+
+test_expect_success 'prefetch and existing log.excludeDecoration values' '
+	git config --unset-all log.excludeDecoration &&
+	git config log.excludeDecoration refs/remotes/remote1/ &&
+	git maintenance run --task=prefetch &&
+
+	git config --get-all log.excludeDecoration >out &&
+	grep refs/remotes/remote1/ out &&
+	grep refs/prefetch/ out &&
+
+	git log --oneline --decorate --all >log &&
+	! grep "prefetch" log &&
+	! grep "remote1" log &&
+	grep "remote2" log &&
+
+	# a second run does not change the config
+	git maintenance run --task=prefetch &&
+	git log --oneline --decorate --all >log2 &&
+	test_cmp log log2
 '
 
 test_expect_success 'loose-objects task' '