Merge pull request #37835 from nextcloud/feat/background-allow-parallel-runs

feat(BackgroundJobs): Allow preventing parallel runs for a job class

3 files changed, 86 insertions, 3 deletions

diff --git a/lib/public/BackgroundJob/IJobList.php b/lib/public/BackgroundJob/IJobList.php
index e8d0380e604..71faefb8825 100644
--- a/lib/public/BackgroundJob/IJobList.php
+++ b/lib/public/BackgroundJob/IJobList.php
@@ -145,4 +145,13 @@ interface IJobList {
 	 * @since 23.0.0
 	 */
 	public function resetBackgroundJob(IJob $job): void;
+
+	/**
+	 * Checks whether a job of the passed class is reserved to run
+	 *
+	 * @param string|null $className
+	 * @return bool
+	 * @since 27.0.0
+	 */
+	public function hasReservedJob(?string $className): bool;
 }
diff --git a/lib/public/BackgroundJob/IParallelAwareJob.php b/lib/public/BackgroundJob/IParallelAwareJob.php
new file mode 100644
index 00000000000..30c69e16b5f
--- /dev/null
+++ b/lib/public/BackgroundJob/IParallelAwareJob.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+
+/**
+ * @copyright Copyright (c) 2023, Marcel Klehr <mklehr@gmx.net>
+ *
+ * @author Marcel Klehr <mklehr@gmx.net>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+namespace OCP\BackgroundJob;
+
+/**
+ * @since 27.0.0
+ */
+interface IParallelAwareJob {
+	/**
+	 * Set this to false to prevent two Jobs from the same class from running in parallel
+	 *
+	 * @param bool $allow
+	 * @return void
+	 * @since 27.0.0
+	 */
+	public function setAllowParallelRuns(bool $allow): void;
+
+	/**
+	 * @return bool
+	 * @since 27.0.0
+	 */
+	public function getAllowParallelRuns(): bool;
+}
diff --git a/lib/public/BackgroundJob/Job.php b/lib/public/BackgroundJob/Job.php
index d60fb5905c9..455fb3d42e7 100644
--- a/lib/public/BackgroundJob/Job.php
+++ b/lib/public/BackgroundJob/Job.php
@@ -38,11 +38,13 @@ use Psr\Log\LoggerInterface;
  *
  * @since 15.0.0
  */
-abstract class Job implements IJob {
+abstract class Job implements IJob, IParallelAwareJob {
 	protected int $id = 0;
 	protected int $lastRun = 0;
 	protected $argument;
 	protected ITimeFactory $time;
+	protected bool $allowParallelRuns = true;
+	private ?ILogger $logger = null;
 
 	/**
 	 * @since 15.0.0
@@ -61,6 +63,7 @@ abstract class Job implements IJob {
 	 * @since 15.0.0
 	 */
 	public function execute(IJobList $jobList, ILogger $logger = null) {
+		$this->logger = $logger;
 		$this->start($jobList);
 	}
 
@@ -70,7 +73,12 @@ abstract class Job implements IJob {
 	 */
 	public function start(IJobList $jobList): void {
 		$jobList->setLastRun($this);
-		$logger = \OCP\Server::get(LoggerInterface::class);
+		$logger = $this->logger ?? \OCP\Server::get(LoggerInterface::class);
+
+		if (!$this->getAllowParallelRuns() && $jobList->hasReservedJob(get_class($this))) {
+			$logger->debug('Skipping ' . get_class($this) . ' job with ID ' . $this->getId() . ' because another job with the same class is already running', ['app' => 'cron']);
+			return;
+		}
 
 		try {
 			$jobStartTime = $this->time->getTime();
@@ -80,7 +88,7 @@ abstract class Job implements IJob {
 
 			$logger->debug('Finished ' . get_class($this) . ' job with ID ' . $this->getId() . ' in ' . $timeTaken . ' seconds', ['app' => 'cron']);
 			$jobList->setExecutionTime($this, $timeTaken);
-		} catch (\Exception $e) {
+		} catch (\Throwable $e) {
 			if ($logger) {
 				$logger->error('Error while running background job (class: ' . get_class($this) . ', arguments: ' . print_r($this->argument, true) . ')', [
 					'app' => 'core',
@@ -133,6 +141,25 @@ abstract class Job implements IJob {
 	}
 
 	/**
+	 * Set this to false to prevent two Jobs from this class from running in parallel
+	 *
+	 * @param bool $allow
+	 * @return void
+	 * @since 27.0.0
+	 */
+	public function setAllowParallelRuns(bool $allow): void {
+		$this->allowParallelRuns = $allow;
+	}
+
+	/**
+	 * @return bool
+	 * @since 27.0.0
+	 */
+	public function getAllowParallelRuns(): bool {
+		return $this->allowParallelRuns;
+	}
+
+	/**
 	 * The actual function that is called to run the job
 	 *
 	 * @param $argument