From c01c516323d91bb23f16186ffe0be09b3c412624 Mon Sep 17 00:00:00 2001
From: Marcel Klehr <mklehr@gmx.net>
Date: Thu, 20 Apr 2023 12:55:06 +0200
Subject: feat(BackgroundJobs): Allow preventing parallel runs for a job class

Signed-off-by: Marcel Klehr <mklehr@gmx.net>
---
 lib/public/BackgroundJob/IJobList.php |  9 +++++++++
 lib/public/BackgroundJob/Job.php      | 25 +++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

(limited to 'lib/public')

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/Job.php b/lib/public/BackgroundJob/Job.php
index d60fb5905c9..89ea41381c9 100644
--- a/lib/public/BackgroundJob/Job.php
+++ b/lib/public/BackgroundJob/Job.php
@@ -43,6 +43,7 @@ abstract class Job implements IJob {
 	protected int $lastRun = 0;
 	protected $argument;
 	protected ITimeFactory $time;
+	protected bool $allowParallelRuns = true;
 
 	/**
 	 * @since 15.0.0
@@ -72,6 +73,11 @@ abstract class Job implements IJob {
 		$jobList->setLastRun($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();
 			$logger->debug('Run ' . get_class($this) . ' job with ID ' . $this->getId(), ['app' => 'cron']);
@@ -132,6 +138,25 @@ abstract class Job implements IJob {
 		return $this->argument;
 	}
 
+	/**
+	 * 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) {
+		$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
 	 *
-- 
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