[2/6] maintenance: use random minute in launchctl scheduler

Commit Message

Derrick Stolee Aug. 7, 2023, 6:51 p.m. UTC

From: Derrick Stolee <[e-mail]>

The get_random_minute() method was created to allow maintenance
schedules to be fixed to a random minute of the hour. This randomness is
only intended to spread out the load from a number of clients, but each
client should have an hour between each maintenance cycle.

Use get_random_minute() when constructing the schedules for launchctl.

The format already includes a 'Minute' key which is modified from 0 to
the random minute.

Signed-off-by: Derrick Stolee <[e-mail]>
---
 builtin/gc.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

Comments

Taylor Blau Aug. 7, 2023, 9:23 p.m. UTC | #1

On Mon, Aug 07, 2023 at 06:51:36PM +0000, Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <[e-mail]>
>
> The get_random_minute() method was created to allow maintenance
> schedules to be fixed to a random minute of the hour. This randomness is
> only intended to spread out the load from a number of clients, but each
> client should have an hour between each maintenance cycle.
>
> Use get_random_minute() when constructing the schedules for launchctl.
>
> The format already includes a 'Minute' key which is modified from 0 to
> the random minute.

All looks good. I was wondering if this is something that we'd want to
allow users to opt out of, but I think that the built-in schedules are
sufficiently vague that we can afford to have a fudge factor on the
exact minute.

Thanks,
Taylor

Patch

diff --git a/builtin/gc.c b/builtin/gc.c
index 66a972bc292..51d6c7620ff 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -1708,7 +1708,6 @@  static int get_schedule_cmd(const char **cmd, int *is_available)
 	return 1;
 }
 
-MAYBE_UNUSED
 static int get_random_minute(void)
 {
 	static int random_initialized = 0;
@@ -1837,6 +1836,7 @@  static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit
 	struct strbuf plist = STRBUF_INIT, plist2 = STRBUF_INIT;
 	struct stat st;
 	const char *cmd = "launchctl";
+	int minute = get_random_minute();
 
 	get_schedule_cmd(&cmd, NULL);
 	preamble = "<?xml version=\"1.0\"?>\n"
@@ -1862,29 +1862,30 @@  static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit
 	case SCHEDULE_HOURLY:
 		repeat = "<dict>\n"
 			 "<key>Hour</key><integer>%d</integer>\n"
-			 "<key>Minute</key><integer>0</integer>\n"
+			 "<key>Minute</key><integer>%d</integer>\n"
 			 "</dict>\n";
 		for (i = 1; i <= 23; i++)
-			strbuf_addf(&plist, repeat, i);
+			strbuf_addf(&plist, repeat, i, minute);
 		break;
 
 	case SCHEDULE_DAILY:
 		repeat = "<dict>\n"
 			 "<key>Day</key><integer>%d</integer>\n"
 			 "<key>Hour</key><integer>0</integer>\n"
-			 "<key>Minute</key><integer>0</integer>\n"
+			 "<key>Minute</key><integer>%d</integer>\n"
 			 "</dict>\n";
 		for (i = 1; i <= 6; i++)
-			strbuf_addf(&plist, repeat, i);
+			strbuf_addf(&plist, repeat, i, minute);
 		break;
 
 	case SCHEDULE_WEEKLY:
-		strbuf_addstr(&plist,
-			      "<dict>\n"
-			      "<key>Day</key><integer>0</integer>\n"
-			      "<key>Hour</key><integer>0</integer>\n"
-			      "<key>Minute</key><integer>0</integer>\n"
-			      "</dict>\n");
+		strbuf_addf(&plist,
+			    "<dict>\n"
+			    "<key>Day</key><integer>0</integer>\n"
+			    "<key>Hour</key><integer>0</integer>\n"
+			    "<key>Minute</key><integer>%d</integer>\n"
+			    "</dict>\n",
+			    minute);
 		break;
 
 	default: