Allow sysadmins to define a maintenance window where heavier jobs can run

Signed-off-by: Joas Schilling <coding@schilljs.com>

config/config.sample.php

@@ -1214,6 +1214,20 @@ $CONFIG = [
  */
 'maintenance' => false,
 
+/**
+ * UTC Hour for maintenance windows
+ *
+ * Some background jobs only run once a day. When an hour is defined for this config,
+ * the background jobs which advertise themselves as not time sensitive will be
+ * delayed during the "working" hours and only run in the 4 hours after the given time.
+ * This is e.g. used for activity expiration, suspicious login training and update checks.
+ *
+ * A value of 1 e.g. will only run these background jobs between 01:00am UTC and 05:00am UTC.
+ *
+ * Defaults to ``100`` which disables the feature
+ */
+'maintenance_window_start' => 1,
+
 
 /**
  * SSL

cron.php

@@ -110,6 +110,28 @@ try {
 			$config->setAppValue('core', 'backgroundjobs_mode', 'cron');
 		}
 
+		// Low-load hours
+		$onlyTimeSensitive = false;
+		$startHour = $config->getSystemValueInt('maintenance_window_start', 100);
+		if ($startHour <= 23) {
+			$date = new \DateTime('now', new \DateTimeZone('UTC'));
+			$currentHour = (int) $date->format('G');
+			$endHour = $startHour + 4;
+
+			if ($startHour <= 20) {
+				// Start time: 01:00
+				// End time: 05:00
+				// Only run sensitive tasks when it's before the start or after the end
+				$onlyTimeSensitive = $currentHour < $startHour || $currentHour > $endHour;
+			} else {
+				// Start time: 23:00
+				// End time: 03:00
+				$endHour -= 24; // Correct the end time from 27:00 to 03:00
+				// Only run sensitive tasks when it's after the end and before the start
+				$onlyTimeSensitive = $currentHour > $endHour && $currentHour < $startHour;
+			}
+		}
+
 		// Work
 		$jobList = \OC::$server->getJobList();
 
@@ -119,7 +141,7 @@ try {
 		$endTime = time() + 14 * 60;
 
 		$executedJobs = [];
-		while ($job = $jobList->getNext()) {
+		while ($job = $jobList->getNext($onlyTimeSensitive)) {
 			if (isset($executedJobs[$job->getId()])) {
 				$jobList->unlockJob($job);
 				break;