[PATCH 1/3] maintenance: extract platform-specific scheduling

["Derrick Stolee via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Derrick Stolee <dstolee@xxxxxxxxxxxxx>

The existing schedule mechanism using 'cron' is supported by POSIX
platforms, but not Windows. It also works slightly differently on
macOS to significant detriment of the user experience. To allow for
new implementations on these platforms, extract a method that
performs the platform-specific scheduling mechanism. This will be
swapped at compile time with new implementations on specialized
platforms.

Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
---
 builtin/gc.c | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index e3098ef6a1..c1f7d9bdc2 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -1494,7 +1494,7 @@ static int maintenance_unregister(void)
 #define BEGIN_LINE "# BEGIN GIT MAINTENANCE SCHEDULE"
 #define END_LINE "# END GIT MAINTENANCE SCHEDULE"
 
-static int update_background_schedule(int run_maintenance)
+static int platform_update_schedule(int run_maintenance, int fd)
 {
 	int result = 0;
 	int in_old_region = 0;
@@ -1503,11 +1503,6 @@ static int update_background_schedule(int run_maintenance)
 	FILE *cron_list, *cron_in;
 	const char *crontab_name;
 	struct strbuf line = STRBUF_INIT;
-	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"));
 
 	crontab_name = getenv("GIT_TEST_CRONTAB");
 	if (!crontab_name)
@@ -1516,12 +1511,11 @@ static int update_background_schedule(int run_maintenance)
 	strvec_split(&crontab_list.args, crontab_name);
 	strvec_push(&crontab_list.args, "-l");
 	crontab_list.in = -1;
-	crontab_list.out = dup(lk.tempfile->fd);
+	crontab_list.out = dup(fd);
 	crontab_list.git_cmd = 0;
 
 	if (start_command(&crontab_list)) {
-		result = error(_("failed to run 'crontab -l'; your system might not support 'cron'"));
-		goto cleanup;
+		return error(_("failed to run 'crontab -l'; your system might not support 'cron'"));
 	}
 
 	/* Ignore exit code, as an empty crontab will return error. */
@@ -1531,7 +1525,7 @@ static int update_background_schedule(int run_maintenance)
 	 * Read from the .lock file, filtering out the old
 	 * schedule while appending the new schedule.
 	 */
-	cron_list = fdopen(lk.tempfile->fd, "r");
+	cron_list = fdopen(fd, "r");
 	rewind(cron_list);
 
 	strvec_split(&crontab_edit.args, crontab_name);
@@ -1539,8 +1533,7 @@ static int update_background_schedule(int run_maintenance)
 	crontab_edit.git_cmd = 0;
 
 	if (start_command(&crontab_edit)) {
-		result = error(_("failed to run 'crontab'; your system might not support 'cron'"));
-		goto cleanup;
+		return error(_("failed to run 'crontab'; your system might not support 'cron'"));
 	}
 
 	cron_in = fdopen(crontab_edit.in, "w");
@@ -1586,13 +1579,24 @@ static int update_background_schedule(int run_maintenance)
 	close(crontab_edit.in);
 
 done_editing:
-	if (finish_command(&crontab_edit)) {
+	if (finish_command(&crontab_edit))
 		result = error(_("'crontab' died"));
-		goto cleanup;
-	}
-	fclose(cron_list);
+	else
+		fclose(cron_list);
+	return result;
+}
+
+static int update_background_schedule(int run_maintenance)
+{
+	int result;
+	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"));
+
+	result = platform_update_schedule(run_maintenance, lk.tempfile->fd);
 
-cleanup:
 	rollback_lock_file(&lk);
 	return result;
 }
-- 
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