On 2021-05-09 23:32:17+0200, Lénaïc Huard <lenaic@xxxxxxxxx> wrote:
> The existing mechanism for scheduling background maintenance is done
> through cron. On Linux systems managed by systemd, systemd provides an
> alternative to schedule recurring tasks: systemd timers.
>
> +static int systemd_timer_enable_unit(int enable,
> + enum schedule_priority schedule,
> + const char *cmd)
> +{
> + struct child_process child = CHILD_PROCESS_INIT;
> + const char *frequency = get_frequency(schedule);
> +
> + strvec_split(&child.args, cmd);
> + strvec_pushl(&child.args, "--user", enable ? "enable" : "disable",
> + "--now", NULL);
> + strvec_pushf(&child.args, "git-maintenance@%s.timer", frequency);
> +
> + if (start_command(&child))
> + die(_("failed to run systemctl"));
> + return finish_command(&child);
> +}
> +
> +static int systemd_timer_delete_unit_templates(void)
> +{
> + char *filename = xdg_config_home_systemd("git-maintenance@.timer");
> + unlink(filename);
> + free(filename);
> +
> + filename = xdg_config_home_systemd("git-maintenance@.service");
> + unlink(filename);
> + free(filename);
> +
> + return 0;
> +}
> +
> +static int systemd_timer_delete_units(const char *cmd)
> +{
> + return systemd_timer_enable_unit(0, SCHEDULE_HOURLY, cmd) ||
> + systemd_timer_enable_unit(0, SCHEDULE_DAILY, cmd) ||
> + systemd_timer_enable_unit(0, SCHEDULE_WEEKLY, cmd) ||
> + systemd_timer_delete_unit_templates();
> +}
I'm not using any systemd-based distros. However, isn't this try to
enable all systemd's {hourly,daily,weekly} user's timer, then delete
the templates?^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W^W
Argh, we're disabling those systemd timer units first, by passing 0 as
first argument of systemd_timer_delete_units.
The fact that I read that twice, and still wrote down above reply
makes me think that above code is not self-explanatory enough.
May we switch to something else? Let's say using enum?
> +static int systemd_timer_write_unit_templates(const char *exec_path)
> +{
> + char *filename;
> + FILE *file;
> + const char *unit;
> +
> + filename = xdg_config_home_systemd("git-maintenance@.timer");
> + if (safe_create_leading_directories(filename))
> + die(_("failed to create directories for '%s'"), filename);
This message is used by other codes, less works for translator, nice!
> + file = xfopen(filename, "w");
> + free(filename);
I'm sure if we should use FREE_AND_NULL(filename) instead?
Since, filename will be reused later.
> +
> + unit = "# This file was created and is maintained by Git.\n"
> + "# Any edits made in this file might be replaced in the future\n"
> + "# by a Git command.\n"
> + "\n"
> + "[Unit]\n"
> + "Description=Optimize Git repositories data\n"
> + "\n"
> + "[Timer]\n"
> + "OnCalendar=%i\n"
> + "Persistent=true\n"
> + "\n"
> + "[Install]\n"
> + "WantedBy=timers.target\n";
> + fputs(unit, file);
> + fclose(file);
> +
> + filename = xdg_config_home_systemd("git-maintenance@.service");
> + if (safe_create_leading_directories(filename))
> + die(_("failed to create directories for '%s'"), filename);
> + file = xfopen(filename, "w");
> + free(filename);
> +
> + unit = "# This file was created and is maintained by Git.\n"
> + "# Any edits made in this file might be replaced in the future\n"
> + "# by a Git command.\n"
> + "\n"
> + "[Unit]\n"
> + "Description=Optimize Git repositories data\n"
> + "\n"
> + "[Service]\n"
> + "Type=oneshot\n"
> + "ExecStart=\"%1$s/git\" --exec-path=\"%1$s\" for-each-repo --config=maintenance.repo maintenance run --schedule=%%i\n"
> + "LockPersonality=yes\n"
> + "MemoryDenyWriteExecute=yes\n"
> + "NoNewPrivileges=yes\n"
> + "RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6\n"
> + "RestrictNamespaces=yes\n"
> + "RestrictRealtime=yes\n"
> + "RestrictSUIDSGID=yes\n"
> + "SystemCallArchitectures=native\n"
> + "SystemCallFilter=@system-service\n";
> + fprintf(file, unit, exec_path);
I think others have strong opinion on not using "%1$s",
and prefer simple "%s" and using "exec_path" twice instead.
> + fclose(file);
> +
> + return 0;
> +}
> +
> +static int systemd_timer_setup_units(const char *cmd)
> +{
> + const char *exec_path = git_exec_path();
> +
> + return systemd_timer_write_unit_templates(exec_path) ||
> + systemd_timer_enable_unit(1, SCHEDULE_HOURLY, cmd) ||
> + systemd_timer_enable_unit(1, SCHEDULE_DAILY, cmd) ||
> + systemd_timer_enable_unit(1, SCHEDULE_WEEKLY, cmd);
> +}
> +
> +static int systemd_timer_update_schedule(int run_maintenance, int fd,
> + const char *cmd)
> +{
> + if (run_maintenance)
> + return systemd_timer_setup_units(cmd);
> + else
> + return systemd_timer_delete_units(cmd);
> +}
> +
> +enum scheduler {
> + SCHEDULER_INVALID = -1,
> + SCHEDULER_AUTO = 0,
> + SCHEDULER_CRON = 1,
> + SCHEDULER_SYSTEMD = 2,
> + SCHEDULER_LAUNCHCTL = 3,
> + SCHEDULER_SCHTASKS = 4,
I think explicitly writing down values doesn't make things clearer,
-1 would be nice, not a strong opinion, though.
Anyway, would it be better to move those type declaration to top of
file?
> +};
> +
> +static const struct {
> + int (*is_available)(const char *cmd);
> + int (*update_schedule)(int run_maintenance, int fd, const char *cmd);
> + const char *cmd;
> +} scheduler_fn[] = {
> + [SCHEDULER_CRON] = { is_crontab_available, crontab_update_schedule,
> + "crontab" },
> + [SCHEDULER_SYSTEMD] = { is_systemd_timer_available,
> + systemd_timer_update_schedule, "systemctl" },
> + [SCHEDULER_LAUNCHCTL] = { is_launchctl_available,
> + launchctl_update_schedule, "launchctl" },
> + [SCHEDULER_SCHTASKS] = { is_schtasks_available,
> + schtasks_update_schedule, "schtasks" },
> +};
> +
> +static enum scheduler parse_scheduler(const char *value)
> +{
> + if (!value)
> + return SCHEDULER_INVALID;
> + else if (!strcasecmp(value, "auto"))
> + return SCHEDULER_AUTO;
> + else if (!strcasecmp(value, "cron") || !strcasecmp(value, "crontab"))
> + return SCHEDULER_CRON;
> + else if (!strcasecmp(value, "systemd") ||
> + !strcasecmp(value, "systemd-timer"))
> + return SCHEDULER_SYSTEMD;
> + else if (!strcasecmp(value, "launchctl"))
> + return SCHEDULER_LAUNCHCTL;
> + else if (!strcasecmp(value, "schtasks"))
> + return SCHEDULER_SCHTASKS;
> + else
> + return SCHEDULER_INVALID;
> +}
> +
> +static int maintenance_opt_scheduler(const struct option *opt, const char *arg,
> + int unset)
> +{
> + enum scheduler *scheduler = opt->value;
> +
> + if (unset)
> + die(_("--no-scheduler is not allowed"));
I think it's better to use OPT_CALLBACK_F in the options list and
we will write below code instead:
BUG_ON_OPT_NEG(unset)
> +
> + *scheduler = parse_scheduler(arg);
> +
> + if (*scheduler == SCHEDULER_INVALID)
> + die(_("unrecognized --scheduler argument '%s'"), arg);
Most of other callbacks do this instead:
return error(_("messsage.... '%s'"), arg);
> +
> + return 0;
> +}
> +
> +struct maintenance_start_opts {
> + enum scheduler scheduler;
> +};
> +
> +static void resolve_auto_scheduler(enum scheduler *scheduler)
> +{
> + if (*scheduler != SCHEDULER_AUTO)
> + return;
> +
> #if defined(__APPLE__)
> -static const char platform_scheduler[] = "launchctl";
> + *scheduler = SCHEDULER_LAUNCHCTL;
> + return;
> +
> #elif defined(GIT_WINDOWS_NATIVE)
> -static const char platform_scheduler[] = "schtasks";
> + *scheduler = SCHEDULER_SCHTASKS;
> + return;
> +
> +#elif defined(__linux__)
> + if (is_systemd_timer_available("systemctl"))
> + *scheduler = SCHEDULER_SYSTEMD;
> + else if (is_crontab_available("crontab"))
> + *scheduler = SCHEDULER_CRON;
> + else
> + die(_("neither systemd timers nor crontab are available"));
> + return;
> +
> #else
> -static const char platform_scheduler[] = "crontab";
> + *scheduler = SCHEDULER_CRON;
> + return;
> #endif
> +}
>
> -static int update_background_schedule(int enable)
> +static void validate_scheduler(enum scheduler scheduler)
> {
> - int result;
> - const char *scheduler = platform_scheduler;
> - const char *cmd = scheduler;
> + const char *cmd;
> +
> + if (scheduler == SCHEDULER_INVALID)
> + BUG("invalid scheduler");
> + if (scheduler == SCHEDULER_AUTO)
> + BUG("resolve_auto_scheduler should have been called before");
> +
> + cmd = scheduler_fn[scheduler].cmd;
> + if (!scheduler_fn[scheduler].is_available(cmd))
> + die(_("%s scheduler is not available"), cmd);
> +}
> +
> +static int update_background_schedule(const struct maintenance_start_opts *opts,
> + int enable)
> +{
> + unsigned int i;
> + int res, result = 0;
> + enum scheduler scheduler;
> + const char *cmd = NULL;
> char *testing;
> struct lock_file lk;
> char *lock_path = xstrfmt("%s/schedule", the_repository->objects->odb->path);
>
> + if (hold_lock_file_for_update(&lk, lock_path, LOCK_NO_DEREF) < 0)
> + return error(_("another process is scheduling background maintenance"));
> +
> testing = xstrdup_or_null(getenv("GIT_TEST_MAINT_SCHEDULER"));
> if (testing) {
> char *sep = strchr(testing, ':');
> if (!sep)
> die("GIT_TEST_MAINT_SCHEDULER unparseable: %s", testing);
> *sep = '\0';
> - scheduler = testing;
> + scheduler = parse_scheduler(testing);
> cmd = sep + 1;
> + result = scheduler_fn[scheduler].update_schedule(
> + enable, get_lock_file_fd(&lk), cmd);
> + goto done;
> }
>
> - if (hold_lock_file_for_update(&lk, lock_path, LOCK_NO_DEREF) < 0)
> - return error(_("another process is scheduling background maintenance"));
> -
> - if (!strcmp(scheduler, "launchctl"))
> - result = launchctl_update_schedule(enable, get_lock_file_fd(&lk), cmd);
> - else if (!strcmp(scheduler, "schtasks"))
> - result = schtasks_update_schedule(enable, get_lock_file_fd(&lk), cmd);
> - else if (!strcmp(scheduler, "crontab"))
> - result = crontab_update_schedule(enable, get_lock_file_fd(&lk), cmd);
> - else
> - die("unknown background scheduler: %s", scheduler);
> + for (i = 1; i < ARRAY_SIZE(scheduler_fn); i++) {
> + int enable_scheduler = enable && (opts->scheduler == i);
> + cmd = scheduler_fn[i].cmd;
> + if (!scheduler_fn[i].is_available(cmd))
> + continue;
> + res = scheduler_fn[i].update_schedule(
> + enable_scheduler, get_lock_file_fd(&lk), cmd);
> + if (enable_scheduler)
> + result = res;
> + }
>
> +done:
> rollback_lock_file(&lk);
> free(testing);
> return result;
> }
>
> -static int maintenance_start(void)
> +static const char *const builtin_maintenance_start_usage[] = {
> + N_("git maintenance start [--scheduler=<scheduler>]"), NULL
> +};
> +
> +static int maintenance_start(int argc, const char **argv, const char *prefix)
> {
> + struct maintenance_start_opts opts;
> + struct option builtin_maintenance_start_options[] = {
> + OPT_CALLBACK(
> + 0, "scheduler", &opts.scheduler, N_("scheduler"),
> + N_("scheduler to use to trigger git maintenance run"),
> + maintenance_opt_scheduler),
Following up my comment above, we're better to use:
OPT_CALLBACK_F(0, "scheduler", &opts.scheduler, N_("scheduler"),
N_("............"),
PARSE_OPT_NONEG, maintenance_opt_scheduler),
> + OPT_END()
> + };
> + memset(&opts, 0, sizeof(opts));
> +
> + argc = parse_options(argc, argv, prefix,
> + builtin_maintenance_start_options,
> + builtin_maintenance_start_usage, 0);
> +
> + resolve_auto_scheduler(&opts.scheduler);
> + validate_scheduler(opts.scheduler);
> +
> + if (argc > 0)
> + usage_with_options(builtin_maintenance_start_usage,
> + builtin_maintenance_start_options);
> +
> if (maintenance_register())
> warning(_("failed to add repo to global config"));
> -
> - return update_background_schedule(1);
> + return update_background_schedule(&opts, 1);
> }
>
> static int maintenance_stop(void)
> {
> - return update_background_schedule(0);
> + return update_background_schedule(NULL, 0);
> }
>
> static const char builtin_maintenance_usage[] = N_("git maintenance <subcommand> [<options>]");
> @@ -2027,7 +2354,7 @@ int cmd_maintenance(int argc, const char **argv, const char *prefix)
> if (!strcmp(argv[1], "run"))
> return maintenance_run(argc - 1, argv + 1, prefix);
> if (!strcmp(argv[1], "start"))
> - return maintenance_start();
> + return maintenance_start(argc - 1, argv + 1, prefix);
> if (!strcmp(argv[1], "stop"))
> return maintenance_stop();
> if (!strcmp(argv[1], "register"))
> diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh
> index 2412d8c5c0..6e6316cd90 100755
> --- a/t/t7900-maintenance.sh
> +++ b/t/t7900-maintenance.sh
> @@ -20,6 +20,20 @@ test_xmllint () {
> fi
> }
>
> +test_lazy_prereq SYSTEMD_ANALYZE '
> + systemd-analyze --help >out &&
> + grep verify out
> +'
> +
> +test_systemd_analyze_verify () {
> + if test_have_prereq SYSTEMD_ANALYZE
> + then
> + systemd-analyze verify "$@"
> + else
> + true
The "else" leg is not necessary.
> + fi
> +}
> +
> test_expect_success 'help text' '
> test_expect_code 129 git maintenance -h 2>err &&
> test_i18ngrep "usage: git maintenance <subcommand>" err &&
> @@ -615,6 +629,43 @@ test_expect_success 'start and stop Windows maintenance' '
> test_cmp expect args
> '
>
> +test_expect_success 'start and stop Linux/systemd maintenance' '
> + write_script print-args <<-\EOF &&
> + echo $* >>args
To avoid any possible incompatibility with zillion echo implementation
out there. printf should be prefered over echo. Not a in this test
case, however, it costs us nothing anyway.
printf "%s\n" "$*"
> + EOF
> +
> + rm -f args &&
> + GIT_TEST_MAINT_SCHEDULER="systemd:./print-args" git maintenance start &&
> +
> + # start registers the repo
> + git config --get --global --fixed-value maintenance.repo "$(pwd)" &&
> +
> + test_systemd_analyze_verify "$HOME/.config/systemd/user/git-maintenance@.service" &&
> +
> + rm -f expect &&
> + for frequency in hourly daily weekly
> + do
> + echo "--user enable --now git-maintenance@${frequency}.timer" >>expect || return 1
> + done &&
And here, we can have a nicer syntax with printf:
printf "--user enable --now git-maintenance@%s.timer\n" hourly daily weekly >expect &&
With printf, we don't even need "rm -f expect" above.
> + test_cmp expect args &&
> +
> + rm -f args &&
> + GIT_TEST_MAINT_SCHEDULER="systemd:./print-args" git maintenance stop &&
> +
> + # stop does not unregister the repo
> + git config --get --global --fixed-value maintenance.repo "$(pwd)" &&
> +
> + test_path_is_missing "$HOME/.config/systemd/user/git-maintenance@.timer" &&
> + test_path_is_missing "$HOME/.config/systemd/user/git-maintenance@.service" &&
> +
> + rm -f expect &&
> + for frequency in hourly daily weekly
> + do
> + echo "--user disable --now git-maintenance@${frequency}.timer" >>expect || return 1
> + done &&
Ditto.
All of this was written without testing, because I don't have any
systemd based system near my hand, right now.
So, please take it with a grain of salt.
--
Danh
